JPH03280700A - Method and apparatus for extracting three-dimensional stereoscopic presence information - Google Patents

Abstract

PURPOSE:To extract only an audio signal whose head is subjected to an acoustic effect by calculating a signal from a 1st microphone recording an audio signal whose head is much subjected to an acoustic effect and a signal from a 2nd microphone recording an audio signal whose head is less subjected to an acoustic effect and extracting a difference between the signals. CONSTITUTION:A 1st microphone a1 is placed near the entry of an external auditory miatus suitable for binaural recording, while a 2nd microphone a2 is installed to a location where a sound resulting from interference, reflection and diffraction caused mainly to a head hardly reaches on the other hand, and a difference component extraction circuit b12 calculates (e.g. subtraction) a difference component between a 1st signal beta obtained from the 1st microphone a1 recording mainly the sound effected at the outside of the head and a 2nd signal alpha obtained from the 2nd microphone a2 recording mainly the sound not much effected at the outside of the head and extracts the result. Thus, only the sound information of interference, reflection and diffraction caused mainly to the head is extracted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to stereoscopic sound recording using the acoustic conditions of a human head, and particularly relates to a method for extracting stereoscopic information, an apparatus, and applications thereof.

[Prior Art] Conventionally, various proposals have been made before 1975 regarding the technology of providing three or more microphones around an imitation human head. In other words, multiple microphone units are provided for each ear.

However, its purpose is broadly divided into directivity control and recording method for multi-channel playback of three or more channels. For example, technology that enables four-channel recording by recording with separate microphone units in the front and back directions. The MS microphone method controls the directivity by installing multiple microphones with different recording directivity states and synthesizing the multiple signals obtained from these microphones.

Another example is a recording method in which a large number of microphones are placed along the circumference of the head.

[Problems to be Solved by the Invention] However, the pinaural information obtained by the above-mentioned conventional technology is not substantially different from normal audio recording by an accurately imitated human head. In other words, only information limited to the recording direction can be recorded in the audio signal of normal pinaural audio recording. Moreover, its principle is also questionable.

Conventional technology is based on the theory that the direction of pinaural information can be limited by determining the direction of sound entering the ear canal. However, for example, sound from a rear sound source goes around the pinna of the ear and enters the external auditory canal from the side, and the amount of sound that enters the ear canal is large. Furthermore, some of the sound from this rear sound source goes around the head in the opposite direction and enters the external auditory canal from the front through a far round trip of more than half a circle. In this way, interference from the auricle, reflections from the head, wraparound sounds, etc. enter the ear canal in very complex directions of incidence, so the direction of incidence at the entrance of the ear canal never has a one-to-one correspondence with the sound source in the desired localization direction. I haven't. Furthermore, it is clear that there is no unnecessary sound among the wraparound sounds that reach these various ears, and therefore, fidelity will be lost even if sound in any direction is missing. Therefore,
It can be pointed out that the conventional method, which aims to record data in a limited manner as described above, is an inadequate recording method with low fidelity based on its fundamental principles.

On the other hand, it can be pointed out that the use of sources recorded using the above-mentioned conventional technology is limited to 4-channel headphone playback that satisfies the recording state and playback state under reversible conditions, or more specialized multi-channel playback. . For example, it is possible to use the 4-channel collected sound limited to the direction of incidence in the external auditory canal for 4 channels of surround sound or speakers, but an accurate reversibility theory does not hold, and faithful reproduction is difficult.

As described above, with the conventional technology, only the same level of localization information as general pinaural recording can be obtained, and therefore, problems such as front-back confusion, insufficient localization, or poor fidelity still remain. The current situation is that

The purpose of the present invention, in order to eliminate the above-mentioned problems, is to obtain extremely clear localization by extracting unique information that occurs exclusively in the human body and which can only be obtained by pinaural recording, and by skillfully using that information. The purpose is to Furthermore, by extracting the unique noise that occurs in the head and subtracting or adding it, it is possible to remove internal head noise or emphasize internal head propagating sound, allowing for clear localization that has never been possible before. The pinaural program source that can be obtained is obtained.

[Means for Solving the Problems] In the present invention, in order to solve the above-mentioned problems, the first signal obtained from the first microphone that exclusively records the sound affected by the external shape of the head provided near the entrance of the external auditory canal; , a second signal obtained from a second microphone, which is installed at a distance from the first microphone to the head and which exclusively records sounds that are not significantly affected by the external shape of the head, is detected by a circuit that extracts a difference component. A method for extracting three-dimensional stereolocation information is provided.

The present invention according to another object provides a first signal obtained from a first microphone that is installed near the entrance of the ear canal and exclusively records sounds affected by the external shape of the head; A method for extracting three-dimensional stereolocation information is provided, characterized in that a circuit for extracting a difference component calculates a third signal obtained from a third microphone that exclusively records audio propagating inside the head.

The present invention according to another object includes a first microphone installed near the entrance of the external auditory canal to exclusively record sounds affected by the external shape of the head; The second part, which exclusively records sounds that are not influenced by
An apparatus for extracting three-dimensional stereolocation information is provided, which is characterized by being equipped with a microphone.

In addition, the present invention has a first microphone installed near the entrance of the external auditory canal to exclusively record sounds affected by the external shape of the head; An apparatus for extracting three-dimensional stereolocation information is provided, characterized in that it is equipped with a third microphone that exclusively records the three-dimensional stereolocation information.

[Function] In the present invention, the first microphone is installed near the entrance of the ear canal, which is suitable for pinaural recording, and the first microphone is placed in a position where the interference, reflection, and diffraction sound that occurs exclusively in the head is difficult to reach, for example, approximately right to the side from the entrance of the ear canal. By installing a second microphone at a position 1 cm or more outside and calculating (for example, subtracting) the difference component between the two microphones and extracting it, only the sound information of interference, reflection, and diffraction that occurs exclusively in the head is extracted. be able to. By amplifying this unextracted signal and adding it to the signal obtained from either the first microphone or the second microphone, it is possible to dramatically emphasize localization and obtain clearly audible pinaural sound. On the other hand, a third microphone for the middle ear is provided between the first microphone and the wave membrane position. This microphone is a microphone that records various sounds transmitted inside the head, and by extracting the difference component between the first microphone and the third microphone,
Only the vibrations transmitted inside the head can be extracted. By returning this Sodero sound to the signal from the first microphone, it is possible to remove the noise that occurs inside the head, or to extract important propagated sounds unique to the head other than the noise contained inside the head. By amplifying the sound propagating inside the head and returning it to the first microphone,
A new type of pinaural program source that actively contains localization information that has been difficult to obtain in the past can be obtained.

Furthermore, it is also possible to extract only these unique sounds that travel inside the human head and use them as special sounds. Note that in order to pick up this intrahead propagation sound, it is particularly effective for ear canal insertion type pinaural recording using a living human head. Therefore, a new specific shape of a microphone inserted into the ear canal can be obtained.

[Example] The present invention will be explained below based on the attached drawings. As far as possible, the same numbers in the drawings are used for parts indicating the same content.

FIG. 1 is a partially sectional left side view showing the a-th embodiment of the present invention;
FIG. 2 is a partially sectional front view showing the ath embodiment of the present invention, FIG. 3 is a sectional view showing the ath embodiment, FIG. 4 is a partially sectional plan view showing the ath embodiment, and FIG. FIG. 6, which is a perspective view of the a-th embodiment with the imitation human head portion removed, is an explanatory diagram of the recording area.

Based on FIGS. 1 to 6, the state around the microphone in the present invention will be described as the a-th embodiment. Thereafter, a circuit for processing a signal obtained from the microphone of the a-th embodiment will be described as a second embodiment with reference to FIG. Further, a C-th embodiment and a d-th embodiment, which are modified embodiments of the a-th embodiment, will be explained with reference to FIGS. 8 to 5.

Example A: Example A is an example of a microphone system for recording audio according to the present invention. Now, the a-th embodiment will be described in detail while listing the individual conditions of each necessary member and the relationship between each member.

Imitation human head: It is desirable that the imitation human head a4 imitate the outer shape and interior of a real human head as much as possible. For example, the outer ear, whose hardness and shape are accurately imitated, the skull, which is closely related to the transmission of sound within the head, and the hollow parts of the nose and throat, which are connected to part of the auditory transmission pathway, are used as needed. As with conventional human head imitations, the auditory transmission path is imitated particularly accurately in the present invention.

Among these, the external ear and external auditory canal are important. Furthermore, in the a-th embodiment, the acoustic transmission state in the eardrum and the vicinity of the majority is simulated by selecting the transmission speed of the material.

First microphone: The first microphone a1 is a microphone provided exclusively to record sounds affected by the head external shape of the imitation human head a4. The target sounds are mainly sounds collected by the outer ear. Furthermore, among the sounds collected by the outer ear, not only the direct sound from the sound source is collected, but also various sounds swirling around the periphery of the head that hit the entire head from the sound source and are reflected, interfered, or wrapped around the head. It has the role of collecting Furthermore, the focus of these collected sounds becomes the entrance to the ear canal. Therefore, in this a-th embodiment, the first microphone a1 was installed at the entrance of the external auditory canal.

However, as long as the first microphone al is installed inside the outer ear, it is possible to record sounds affected by the target external shape of the head, although there is a difference in sound collection efficiency.

Second microphone: The second microphone is a microphone provided exclusively to record sounds that are not affected by the external shape of the head of the imitation human head A4. This influence means the influence that occurs in the head environment described with respect to the first microphone a1.

In order to achieve this objective, it is necessary to hold the following relationship at most.

Regarding the content of head-affected sound between the sound affected by the head outline of the imitation human head A4 and the sound that reached the microphone without being affected by the head outline, the audio signal recorded by the second microphone is the same as the sound signal recorded by the first microphone. The content rate is lower than the audio signal recorded by microphone a1.

Furthermore, the following two methods are available for establishing the above relationship.

#Method: If the direction of the sound source containing reverberation to be recorded is in a single direction or limited to a single direction, set the distance between the first microphone and the above sound source as ◇, and the distance between the second microphone and the above sound source. If you use ◇ as a mouth, you can make a large difference between ◇ and mouth. This is because, under the condition that the sound arrives in a single direction, the distance difference can be corrected by delaying one of the microphones, and the distance difference can be substantially eliminated. However, the following conditions must be met.

■...The distance difference between ◇ and the mouth is not preferable because if they are too far apart, there will be a large difference in acoustic characteristics between the recording results of the first microphone a1 and the second microphone a5 due to propagation loss in the air.

For example, if the distance is kept within 30 cm, there will be no problem.

(2) The second microphone is positioned farther from the imitation human head M than the first microphone a1.

(2) Both the first microphone a1 and the second microphone use microphone units having the same directivity, and furthermore, the respective microphones are installed in the same direction with respect to the head. These conditions are because it is necessary to make the directivity conditions the same when calculating the signal obtained from the first microphone a1 and the signal obtained from the second microphone. This is because even if signals with different directivities are calculated, the combined directivity characteristics of the two microphones will only change as in the conventional MS type. Furthermore, when omnidirectional microphones are used, the orientations of the microphone units are not affected much, so the orientations of these microphone units do not need to be matched exactly. Furthermore, the directivity matching is necessary only in the frequency band to be calculated, and there is no particular need for matching in other frequency bands. For example, if the frequency band for calculation purposes is 100 Hz to 11 kHz, the configuration of the present invention can be applied to any directivity state in the frequency bands above 11 kHz and below 100 Hz.

The second microphone described in #means above becomes the second microphone a5 when compared with the drawing.

ΣMeasures: If the sound source to be recorded is located in multiple directions, regardless of the presence or absence of reverberation, it is necessary to satisfy the conditions of ■■■.

■...The second microphone is an imitation human head ml from the first microphone a1
Position it away from the camera.

(2) The distance between the second microphone and the first microphone a1 is desirably set to less than half of the upper limit wavelength of the frequency range to be extracted.

The conditions of ■ and ■ above are conditions in which # means and means 8 are both related, and when the type of recording sound source is not determined in advance, the first microphone a1 and the second microphone a1 and
It can be seen that it is preferable to position the microphone a2.

The condition (2) above is a constraint that arises because the delay processing (2) cannot be performed. Also, the reason why delay processing is not possible is that if the target sound to be recorded comes from only one direction, it is possible to accurately correct the phase shift using delay processing, but when multiple sounds coming from different directions This is because it is impossible to match the phase shift due to delay processing. For this purpose, each microphone unit must be positioned within a half wavelength of the upper limit frequency to be extracted, as described in (2) above.

The second microphone described in the above eight means is the second microphone a2 in each figure. In addition, the first microphone a1 and the second microphone a2
The positional relationship will be explained in more detail. If the first microphone a1 is placed at a distance of Acm from the surface of the head excluding the outer ear, the second microphone a2 may be placed at a distance of (A+Δ)cm that is even larger than Acm. is necessary. As a result, at least the second microphone a2 can record sound that is less affected by the imitation human head a4 than the first microphone a1.

Now, the frequency band affected by the head, which is characterized by pinaural sound, is mainly affected in the band below 13 kHz. These characteristics are described in auditory handbooks and the like and are well known. Furthermore, the upper limit of the important head effect is around 8, and anything above that is due to mere shielding of the outer ear, and this shielding effect is information that could be recorded relatively accurately even with conventional pinaural recording. Note that this shielding influence does not mean an influence accompanied by wave nature due to acoustic diffraction or interference, but a shielding influence that is affected only by straight propagation like light. On the other hand, there is also a large head effect around 3 kHz. For example, when using media with a narrow frequency band such as a telephone line, at least 3kHz
The upper limit of the frequency to be extracted is set as above. In this case, it is sufficient to set the above-mentioned Δ within 5.5 cm. By the way, if 8kHz is the upper limit of the frequency to be extracted above, △ is Z
Similarly, at 13 kHz, Δ needs to be within 1.3 cm. The upper limit of the frequency to be extracted varies depending on the various media, but if the upper limit of the average audible frequency for adults is 16 kHz, Δ is within I Cm, and the microphones are placed extremely close to each other. If the first microphone a1 is installed just above the entrance of the ear canal, the second microphone a2, which is 1 cm away from there, will be placed inside the outer ear, rather than outside. As a result, these 2
The difference in signals recorded by two microphones cannot be captured sufficiently,
Extraction of difference components, which will be described later, cannot be achieved satisfactorily.

Note that if only the positional relationship with respect to the outer ear is described as described above, one hand will be left out. In other words, the problem is in what direction the distance Δ can be separated. For example, you can remove the head (skull, etc.) by simply moving it away from the outer ear.
Suppose that there is no distance between them, but a distance of △ is provided between them. Specifically, when the second microphone a2 is installed near the earlobe of the outer ear, the distance from the first microphone a1 at the entrance of the ear canal is △
is approximately 2 cm. In this case, sounds that rely only on the outer ear to collect, such as direct sounds that are collected in the recesses that are part of the outer ear, such as the foossa, scapha, and concha, and reach the ear canal, reach only the first microphone a1. , it does not reach the second microphone a2. This difference is therefore obtained. However, for sounds that are affected by the entire head, the first microphone a
Since the distances from the head of the first and second microphones a2 are almost the same, there is almost no difference between them. Therefore, the signal obtained when extracting the difference component, which will be described later, is only affected by the external ear. Of course, this is sufficiently effective if the purpose is to extract only the sound collection effect in the outer ear. This purpose is diverse and ambiguous. This is because in the conventional recording method for pinaural recording,
This is because there are various grades and ways of thinking, such as only the outer ear, and there is no consistent concept of a dummy head. The present invention itself is not ambiguous in this respect. On the other hand, it is easy to determine the most preferable dummy head condition. That is, a human body wearing clothes, having normal hair, and a normal head shape and torso. For the above-mentioned ideal imitation human head (human body), the first microphone a1 and the second microphone a are the most preferable for recording multiple sound sources.
The effective installation location for item 2 is as follows.

A first microphone a1 is installed in the ear canal, and then a second microphone a2 is placed on a line connecting the entrances of both ear canals of both ears, separated by Δcm. This △ is an important value that limits the upper limit frequency when calculating the difference component described later, and a value as small as possible is desirable. On the other hand, this △ is the shape of the head including the outer ear, as shown in Figure 6. It is related to the relative position of

In other words, the second microphone a2S has a second microphone a2 located outside the outer ear, and the second microphone a2 has a second microphone a2 located inside the outer ear.
At n, the influence of external ear shielding becomes extreme. That is, in the second microphone a2s, the difference in the shielding effect is sufficiently extracted when extracting the difference component described later, whereas in the second microphone a2n, the difference in the shielding effect is difficult to be extracted. Overall, the preferred value of Δ is the maximum value of Δ when the second microphone a2s is located slightly outside the outer ear, and if the upper limit of the frequency required for extracting the difference component, which will be described later, is lower, it does not matter. If so, use this maximum value. On the other hand, if the upper limit of this frequency is 12 kHz, it will be approximately 1.5 cm. Although this value should vary somewhat depending on the size of the head, it is a value that generally satisfies the various conditions described above.

Note that only when the sound source is the sound reproduced by a speaker, it can be reproduced many times under the same conditions, so recording with the first microphone a1 with the imitation human head 4a present, and then recording with the first microphone a1. By recording the signal from the first microphone a1 with the imitation human head 4a remaining and removing it, and later performing synchronization processing on these two separately recorded signals, extraction of a difference component, which will be described later, can be achieved.

Third microphone: The third microphone a3 is a microphone used exclusively to record the sound propagating inside the imitation human head a4. In the a-th embodiment, this microphone is provided between the first microphone a1 and the eardrum position. In other words, it is placed in the middle of the ear canal. However, since it is most effective to capture sound vibrations that propagate inside the head and directly reach the delayed sound, the most preferable position of the third microphone a3 is the majority position (see FIG. 6). However, this third microphone a3
When installing the ear canal, it is predicted that it will most often be used by inserting it into the human head, so in this embodiment a, it is installed in the middle of the external auditory canal (see Fig. 6). The sound propagating inside the head has a propagation path that excites the wall surface of the external auditory canal, further excites the air in the external auditory canal, and then excites the eardrum, so it makes a lot of sense to install the third microphone a3 in the external auditory canal. There is. Note that this third microphone a3 is preferably
A microphone with the same characteristics as microphone a1 is preferable. However, due to the nature of the sound that is the purpose of collecting sound, it is the sound that has propagated through the head.
In addition to the method of providing the first microphone a1 in the external auditory canal space in the same direction as the first microphone a1, it is also possible to use a method of pressing the microphone against the external auditory canal wall surface to more efficiently collect the sound propagating inside the head.

The necessary frequency range may be comparable to the frequency characteristics of the medium range where the above-mentioned propagated sound is transmitted. For example, empirically, 400Hz ~ 3
It may be considered sufficient to secure the kHz range. As a result, the distance between the third microphone a3 and the first microphone a1 is 5.5 cm.
The condition that it is within the range is obtained. In addition, the distance between the microphones is not set strictly, because the phase of the collected sound due to the difference in microphone position comes through the air medium and the head material medium. This is because it is complex and cannot be specified. Furthermore, if the ear canal is completely blocked by the first microphone a1 located at the entrance of the ear canal, it is possible that the sound from the air medium will not be mixed into the third microphone a3. In this case, although there is still the problem of recording with a microphone located several centimeters outside of the intended majority position toward the outer ear, the sound from the third microphone a3 remains unchanged.
It is passed as a sound vibration that propagates exclusively inside the head and directly reaches the late stage.

In this case, a sound extremely similar to the sound signal that would be directly vibrated to the majority is obtained at the majority position. The audio signal obtained here is purely head-propagated audio, but it also includes signals specific to head-propagation and signals that are no different from audio recorded by an extra-head microphone, such as the second microphone a2. ing.

To put it in simple terms, the sound that arrives through complex interference such as the cavity effect of the skull and ear, nose and throat is a signal that is unique to head propagation. There is a sound that is simple and reaches the sound waveform without being distorted, and is a signal similar to that of the second microphone a2, and is difficult to distinguish from a signal unique to propagated sound.

Hemispherical member: The hemispherical member a6 is a sound absorbing material that rotates around the imitation human head a4, and is a member used to limit the sound source direction of recording to a single direction. And it has the following characteristics.

It is mainly made of sound-absorbing material, and if desired, a board such as wood can be provided in the shape of a sandwich inside the sound-absorbing material. This board also serves as a bootstrap to increase low-frequency absorption.

The rotational movement of the tone arm of a stereo is made about the approximate center of the imitation human head a4. In other words, vertical and horizontal rotation is performed while the lateral direction is restricted. In order to perform this rotational movement, a gimbal type rotation support part a7
It is equipped with Each rotating part of the rotating support part a7 is provided with a servo motor that controls vertical and horizontal rotation, and a detection device a8 that also serves as a detector that can accurately determine the rotation angle.

The most preferable center of rotation is the center position connecting both ears of the imitation human head a4.

The overall shape is a hemisphere with a thickness of 5 cm to 10 cm, and there is a cut alo at the bottom to avoid the support column A9 when rotating, a manual handle all at the rear, and a handle on the left and right inside. Place the second microphone a few cm away from the inner wall of the sound-absorbing material.
It is equipped with 5. Further, an auxiliary cylindrical sound absorbing material a12 can be attached to the front opening side with double-sided tape or the like.

Second Embodiment A circuit for processing signals obtained from each of the microphones of the above-described a-th embodiment will be explained with reference to FIG.

This embodiment will be referred to as the first embodiment for convenience.

In the figure, bl, b2. b3 is a microphone amplifier, b4.
b5. Field b7 is a filter, b8. b9, blo,
bll is a delay circuit, bl2. bl3 is a circuit for extracting difference components; bl4, b15. bl6 is a mixer, bl7. bl8 is an amplifier.

Two types of novel information can be obtained by the processing of the circuit of the first embodiment described below. First, a circuit B1 extracts the difference component between the first microphone a1 and the second microphone a5.
Explain.

The signal captured on the right side of the first microphone a1 is the microphone amplifier b
It is amplified by 2. β this amplified signal.

shall be. β゛ passes through a filter b5 that passes between 100Hz and 11kHz, and is turned on by a delay circuit blo.
The signal β°° delayed by X seconds is input to the circuit b12 for extracting the difference component.

On the other hand, the signal captured on the right side of the second microphone a5 is amplified by the microphone amplifier b1. Let this amplified signal be ao. ao passes through a filter b4 that passes between 100 Hz and 11 kHz, and al, which is delayed by a second by a delay circuit b9, is input to a circuit b12 that extracts the difference component. Furthermore, ao is also connected to another circuit that simply delays the delay circuit b8 without passing through the filter, and the resulting signal is the output signal out.
It is 5. Filter b4 that passes between 100Hz and 11kHz. The role of b5 is to narrow down the frequency range in which the difference component is to be calculated, and to preliminarily cut out frequency ranges that have no meaning even if calculated due to differences in microphone positions and differences in directivity characteristics.

Therefore, it is necessary to change the characteristics of this filter to an arbitrary value depending on the position and characteristics of the microphone.

The output of the circuit b12 that extracts the difference component is the amplifier b14.
is amplified at any magnification. The result is the output signal (+u
It is tl. The output signal out1 and the output signal out5 are mixed by the mixer b14, and the result becomes the output signal out2.

Now, this K is an algebra representing the time taken for the sound to move from the rotating first microphone a1 on one side to the first microphone a1 on the other side. For example, if the second microphone a5 is installed perpendicular to the sound source and the first microphone a1 is rotated freely, the difference in position between the right side (left side) of the first microphone a1 and the right side (left side) of the second microphone a5 The maximum value of the phase difference that occurs corresponds to this K. For example, the straight line distance between Daiichi Microphone's binaural microphones is 20
cm, and if the sound were to travel in a straight line, this distance difference would be approximately 0.6 m5ec. In reality, it often reaches by going around the head, so it will be longer than the above 0.6m5ec. On the other hand, in the state shown in Figure 8, the distance difference between the right side microphone of the first microphone a1 and the right side microphone of the second microphone a5 is 6.
cm. The time difference between the arrival of sound emitted from a sound source several meters away to two microphones is approximately 0.18 m5ec.
Therefore, X = 0.18 m5ec. This X again
can be calculated by the relative rotation of the first microphone a1 and the second microphone a5. In this embodiment, X is determined by sequential calculations corresponding to the detection information obtained by the detection device a8 provided on the hemispherical member a6 described above or the detection device a8 shown in FIG.

The explanation of the second embodiment will be supplemented based on the specific numerical values shown in FIG.

To the right of the first microphone a1 is the second microphone a5 with respect to the sound source.
It is located 60m behind the right side of Therefore, the time difference between the signal β obtained from each microphone and a is such that when a is used as a reference, β is X seconds later than a. In order to simply eliminate this difference, the delay time of the delay circuit b9 is set to 0 seconds, and the delay time of the delay circuit blo is set to X seconds, thereby eliminating the above-mentioned time difference. However, since a is slower than β on the left side, a delay circuit on the β side (not shown on the left side) must be used to advance X seconds. However, although information can be delayed, it is impossible to advance it. Therefore, by adding a biasing delay time K to all the left and right delay circuits a and β, the time difference between all the left and right a and β signals can be made zero just by the delay.

Now, when the first microphone and the second microphone are at 90 degrees, the time difference between the two microphones is the largest, so this time is defined as the deviation time. Here, if K = 0.6m5e, the delay circuit b9 has a fixed delay time of 0.6m5ec seconds. And the delay circuit blo adds -0.18m5ec in addition to 0.6m5ec, and the result is 0.42m
The delay time is 5ec. A'' and β'' obtained in the above manner have no time lag, and the calculation in the circuit b12 for extracting the difference component becomes smooth.

Next, a supplementary explanation of the circuit b12 for extracting the difference component will be given.

The simplest example of this circuit is a circuit that performs simple subtraction on analog signals. This can be easily accomplished using a well-known circuit, a differential operational amplifier. It is also an effective means, if desired, to perform arithmetic operations on the input signal for each spectrum using a plurality of operational amplification operational amplifiers each having a different amplification factor, and to synthesize the results. Through these calculations, the first signal β obtained from the first microphone ml, which is installed near the entrance of the ear canal and exclusively records the sound affected by the head outline, and the first signal β obtained from the first microphone ml, which is installed at a distance from the head from the first microphone a1, are determined. The result is a difference from the second signal a obtained from the second micro, which exclusively records sounds that are less affected by the head shape. Among the signal components of β, which is a normal pinaural signal, there are components that are not affected by the head. This signal is deleted, and only the audio signal strongly affected by the head is extracted by the circuit b12 for extracting the difference component. In other words, information specific to the pinaural that is exclusively affected by the head is extracted.

It can be seen that the circuit Bl described above can obtain a pinaural signal in which only the three-dimensional information generated exclusively in the head is emphasized.

In addition, when the signal of the second microphone a2 is processed by the circuit B1 instead of the second microphone a5, all the delay circuits are set to zero, or only the delay circuit b9 connected to the second microphone a2 is set to zero. delay. This delay time is the time it takes the sound to travel the above Δcm 3.3/Δ(s
It is desirable that the value does not exceed ec). In other words,
The value obtained by 3.3/△(sec) is that when the sound source is right next to the head, the time difference between the second microphone and the first microphone is the minimum, and when the sound source is in front or behind the head, the above time difference is The time difference is 3 compared to when the delay circuit is set to zero.
．． It becomes larger by 3/△(field C). Therefore, taking the middle point between these contradictory conditions, the delay time is 3.3
/ 2△ (sec), the time difference caused by the distance difference △ for sound sources in almost all directions is halved,
The upper limit of the frequency at which the difference component can be calculated is doubled. Alternatively, by utilizing this advantage and doubling Δ, it becomes possible to move the second microphone a2 further away from the head.

Next, a circuit B2 for extracting a difference component between the first microphone a1 and the third microphone a3 will be explained.

The signal captured on the right side of the third microphone a3 is the microphone amplifier b
It is amplified by 3. Let this amplified signal be γ. The signal γ゛ is passed through filter b7 between 400Hz and 3kHz.
and enters one input of the circuit b13 that extracts the difference component. In addition, the other input of the circuit b13 for extracting the difference component is connected to the signal β
It is input via a filter b6 that passes between z and 3 kHz. The circuit b13 for extracting the difference component has the same circuit configuration as the circuit b12 for extracting the difference component in the circuit al. With this circuit, the first signal β obtained from the first microphone (a1), which is installed near the entrance of the ear canal and exclusively records the sound affected by the external shape of the head, and the head that is installed inside the head from the first microphone a1. The result is a difference from the third signal γ obtained from the third microphone a3, which exclusively records the sound propagating inside. Similar to β, which is a normal pinaural signal, γ includes various interference sounds affected by the external shape of the head, and is collected while traveling inside the head. Only unique information such as reflections and interference caused by the human body tissue inside the head is extracted as it travels through the head.

In other words, information that is exclusively influenced within the head is extracted.

The signal output from the circuit b13 for extracting this difference component is amplified by an arbitrary magnification by the amplifier b18, and the obtained signal is the signal out3.

The signal out3 and the signal β° are each input to a mixer b15, and the output thereof is delayed by a fixed number of seconds by a delay circuit bll, and then further input to a mixer b16.

The mixer b16 is further inputted with the signal out2 described in the circuit al. The mixed signal becomes the signal out4.

Now, the reason why the filter b6 passes the frequency between 400 Hz and 3 kHz is because the phase difference between the left and right is small below 400 Hz in the low frequency range, so there is little value in extracting it as a stereophonic signal, and therefore it is cut. Furthermore, the upper limit of 3 kHz in the high frequency band is set in order to eliminate the frequency difference between the two when extracting the difference component by limiting the high frequency band that is difficult to propagate due to head propagation.

Embodiment C FIGS. 9, 10, 11, 12, 13a and 13b show a modification of the C embodiment, which will be referred to as the C embodiment for the purpose of explanation.

Embodiment C is constructed based on the assumption that an imitation human head is mainly used, whereas Embodiment C uses a so-called sonde method that can be used even when attached to a human head. Give an example.

Fig. 9 is a side view showing how the C embodiment is used, Fig. 10 is an explanatory cross-sectional view of the C embodiment inserted into a human head, and Fig. 11 is a side view showing the C embodiment in use. FIG. 3 is a front view showing the outer shape of the embodiment. Moreover, FIG. 13, FIG. 13a, and FIG. 13b are explanatory diagrams showing modified embodiments of the C-th embodiment.

The members provided in the Cth embodiment are almost the same as those in the Cth embodiment, and the differences will be described below.

The purpose is to enable the special pinaural recording of the present invention by inserting it into the human head.

The outer wall C1 is made of a porous material that is flexible enough to have little effect on the body even when inserted into the external auditory canal.

Here, porous polyethylene is used. Further, a convex portion c3 is provided at the midsection of the outer wall c1. This is a hook for positioning the outer wall c1 at the entrance of the external auditory canal.

On the other hand, in front of the first microphone a1 and the second microphone a2, a space c5 is provided between the outer wall c1 and each microphone.

This space also serves as a windscreen. In particular, when the C-th embodiment is made to have a similar external shape to a normal inner-ear type headphone as shown in FIG. 12, the space C5 can be used as the position where the unit of the normal headphone is inserted.

And - although they look like ordinary headphones, they actually have an outer wall structure built for a windscreen. Further, a second microphone a2 is supported at one end of the outer wall.

FIG. 13a shows a C-th embodiment in which the second microphone a2 is provided on the side wall of the outer ear. The second microphone A2 can be easily installed using a clip for the outer ear, which is conventionally known as an accessory, and the resonance element of the support is small, making it difficult for unnecessary vibration sounds to enter the microphone, and the clip is made to be attached to the side of the outer ear. Because it is supported, it can be placed at the tip of the outer ear without any adjustment. Furthermore, Fig. 13b shows an example in which the second microphone a2 is supported by an ear hook, which is made of a flexible material coated with polyethylene material around a metal core material, and the direction and position of the microphone are fixed. Able to move freely and stably. Another feature of the kake is that it can be kept in the same position even when repaired. Note that the operation of the C-th embodiment described above is for achieving the same purpose as the two means of the C-th embodiment.

dth embodiment: FIGS. 14 and 15 are a sectional view and a front view showing the dth embodiment. This dth embodiment shows an example in which the difference component can be obtained mechanically without using an electric circuit. In other words, this is an example in which the complicated means described in the C-th and 2-th embodiments can be obtained with only one microphone.

The fourth microphone d1 is a microphone unit having a figure-8-shaped directional characteristic, and is provided with a tube d3 on the inner ear side. This tube d
3 extends to a position several cm away from the outer ear, and the opening d5 of this tube d3 is open in the shape of a morning glory. Also, tube d3
It is desirable that the tapered shape becomes narrower as it approaches the microphone. Now, with this simple structure, the sound that enters from the opening d5 is the sound that is not affected much by the head, similar to the second microphone a2. The sound that directly enters the fourth microphone d1 is the same as the sound input to the first microphone, and the sound is greatly influenced by the head. And tube d
3 is connected to the back side of the fourth microphone d1, and the vibration of the microphone is excited in the opposite phase.

Therefore, with the above structure, the opening d5 and the fourth microphone d
Only the difference component of the voice directly entering the microphone group 1 can vibrate the diaphragm of the fourth microphone group and its signal can be extracted.

In the dth embodiment, not only is it possible to mechanically extract the difference component, but also because the tube d3 is used, the position at which the second microphone a2 picks up the sound is relatively far from the external auditory canal. There is an advantage that the phase difference does not become large even if it is provided. In FIG. 14, when Masato has the sound source to be recorded, when the second microphone a2 is brought to the opening d5 of the tube d3, the time difference due to the distance d7 is with respect to the fourth microphone di, This dth embodiment has the advantage that only the distance d8 that the tube goes around to the back side of the fourth microphone appears as a time difference, and the phase difference is small. however,
When the recorded sound source is in front, there is no difference at all. Therefore, the above-mentioned difference can be eliminated in all directions by arranging a large number of the tubes d3 not only horizontally, but also scattered in more than ten directions. By providing a tube beyond the inside of the head, such as the dotted line tube d3, it becomes possible to record audio that can ignore the presence of the head. This eliminates the influence of the head, which was previously absent, and enables more accurate extraction of three-dimensional information.

Finally, using Σ of the Cth embodiment and the circuit of the second embodiment, an impulse signal sound source is placed in an arbitrary direction, and the various signals obtained by the first embodiment are applied to the impulse signal. The output signal is stored in a DSP circuit or the like to constitute a transfer characteristic compensation circuit. By preparing this transfer characteristic compensation circuit for each required direction and installing it between the effector processing circuits such as mixers, it is possible to improve the reverberation that can be achieved using currently commercially available DSPs for signals that do not have 3D information, such as line-recorded sounds. It can be used as a new effector that can easily add directional information.

[Effects of the Invention] As explained above, the present invention provides a first microphone that records sounds that are more influenced by the acoustics of the head, and a microphone that records sounds that are influenced less by the acoustics of the head than the first microphone. The present invention is a microphone for extracting three-dimensional stereolocation information, characterized in that it includes a second microphone. Therefore, it becomes possible to immediately subtract the signals from these two types of microphones, extract the difference signal, and extract only the audio signal affected by the acoustic effects of the head. Furthermore, this microphone makes it possible to record the signals from these two types of microphones using a multi-channel recorder or the like, and then extract the difference component at any time.

In addition, the present invention, which has another purpose, is equipped with a third microphone that records sounds that receive more sounds that propagate inside the head, and a first microphone that receives fewer sounds that propagate inside the head than the third microphone. This is a microphone for extracting three-dimensional stereolocation information. Therefore, by immediately subtracting the signals from these two types of microphones and extracting the difference signal, it becomes possible to extract only the audio signal propagating inside the head.

Furthermore, this microphone enables recording of the signals from these two types of microphones using a multi-channel recorder or the like, and then extracting the difference component at any time.

The present invention, which has another object, passes two slightly different audio signals through a circuit that extracts a difference component by canceling the phase shift with a delay circuit and performing a process such as subtraction in a state where the phases are matched. This is a circuit for extracting three-dimensional stereolocation information that is provided with an amplifier that emphasizes the extracted signal and adds the emphasized extracted signal to either of the above two signals. Therefore,
For example, by processing signals from the various microphones explained in the Cth embodiment and the Cth embodiment with this circuit, two
It is possible to obtain an audio signal with two major characteristics. One is a special pinaural sound that arbitrarily exaggerates the acoustic effects caused by the external shape of the head, and the other is a special pinaural sound that arbitrarily exaggerates the acoustic effects caused by propagation inside the head. You can get pinaural audio.

Now, by combining the two types of special pinaurals mentioned above, information about the outer circumference of the head and information propagating inside the head can be arbitrarily extracted, and this extracted signal is concentrated and made stronger by means of amplification, and finally, By adding this concentrated acoustic signal to the signal from the most normal microphone, for example, the second microphone which is less affected by the acoustic influence of the head, a program source with intense localization that has not been possible in the past can be obtained. Until now, a signal with enhanced localization can be obtained that can compensate for insufficient localization due to head shape errors between the listener and during recording, and has a useful effect that can solve the problem of individual differences in pinaural. In addition, in order to obtain the above effect, the first microphone and the second microphone or the first microphone and the third microphone are connected.
A pinaural microphone is provided that includes a microphone.

[Brief explanation of drawings]

FIG. 1 is a partially sectional left side view showing a C-th embodiment of the present invention;
FIG. 2 is a partially sectional front view showing the C embodiment of the present invention, FIG. 3 is a sectional view showing the C embodiment, FIG. 4 is a partially sectional plan view showing the C embodiment, and FIG. Figure 6 is an explanatory diagram of the recording area, a block diagram showing the second embodiment, which is an example of processing the signals obtained from each microphone of the embodiment C. Circuit diagram, Figure 8 is an explanatory diagram showing the positional relationship of the microphones, Figures 9, 10, 11, 12, 1
3a and 13b are explanatory diagrams showing a modification of the C-th embodiment, FIG. 14 is a sectional view showing the d-th embodiment, and FIG. 15 is a front view showing the d-th embodiment. In the figure, al.first microphone, β.-first signal, a2. a5 second microphone, α second signal, b12. b13...Circuit for extracting the difference component, a3 Third microphone, γ...Third signal, recording audio direction limiting device. Procedural amendment (“8 July 24, 1990

Claims (1)

[Scope of Claims] 1. A first signal (β) obtained from a first microphone (a1) that exclusively records sounds affected by the external shape of the head provided near the entrance of the ear canal; ) and the second signal (α) obtained from the second microphone (a2, a5), which exclusively records the sound that is not affected by the external shape of the head, which is placed further away from the head, and the difference component is Circuit to extract (b1
2) A method for extracting three-dimensional stereolocation information. 2. The first signal (β) obtained from the first microphone (a1), which is installed near the entrance of the ear canal and exclusively records the sound affected by the external shape of the head, and the first signal (β) from the first microphone (a1) to the inside of the head. A three-dimensional device characterized in that a third signal (γ) obtained from a third microphone (a3) that exclusively records the sound propagating inside the installed head is calculated by a circuit (b13) that extracts a difference component. How to extract stereolocation information. 3. A first microphone (a1) installed near the entrance of the external auditory canal that exclusively records sounds affected by the external shape of the head; A second microphone that exclusively records sounds that are not affected by much (
A3-dimensional stereolocation information extraction device characterized by comprising: a2, a5). 4. A first microphone (a1) installed near the entrance of the ear canal to exclusively record sounds affected by the external shape of the head; and a first microphone (a1) installed closer to the inside of the head to record sounds propagating inside the head. An apparatus for extracting three-dimensional stereolocation information, characterized by comprising a third microphone (a3) for exclusive recording. 5. At least in the frequency band calculated by the difference component extraction circuit (b12), check that the first microphone (a1) and the second microphone (a2, a5) are both omnidirectional. A method for extracting three-dimensional stereolocation information according to claim 1. 6. At least in the frequency band calculated by the circuit (b12) for extracting the difference component, the first microphone (a1) and the second microphone (a2, a5) both use microphones that have directivity, and 2. The method for extracting three-dimensional stereolocation information according to claim 1, wherein the microphones are oriented in substantially the same direction. 7. A claim in which the signal of the second microphone calculated by the circuit for extracting the difference component (b12) is the second microphone (a5) provided inside the rotatably installed recording audio direction limiting device (a6). 1. The method for extracting three-dimensional stereolocation information as described in 1. 8. A recording device comprising a storage space for storing a binaural recording head and a sound-deadening material having at least one opening extending outward from the storage space, and regulating the direction of sound arriving at the stored binaural recording head. The apparatus for extracting three-dimensional stereolocation information according to claim 3, further comprising an audio direction limiting device (a6). .