WO2024254820A1 - Procédé permettant de concevoir un haut-parleur à champ sonore constant - Google Patents

Procédé permettant de concevoir un haut-parleur à champ sonore constant Download PDF

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Publication number
WO2024254820A1
WO2024254820A1 PCT/CN2023/100411 CN2023100411W WO2024254820A1 WO 2024254820 A1 WO2024254820 A1 WO 2024254820A1 CN 2023100411 W CN2023100411 W CN 2023100411W WO 2024254820 A1 WO2024254820 A1 WO 2024254820A1
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WIPO (PCT)
Prior art keywords
audio
channel input
crossover point
sound field
frequency
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Ceased
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PCT/CN2023/100411
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English (en)
Inventor
Guochao LU
Cheng JIANG
Yu Jiang
Jianwen ZHENG
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Harman International Industries Inc
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Harman International Industries Inc
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Priority to PCT/CN2023/100411 priority Critical patent/WO2024254820A1/fr
Priority to CN202380099423.0A priority patent/CN121312153A/zh
Priority to EP23745382.4A priority patent/EP4728755A1/fr
Publication of WO2024254820A1 publication Critical patent/WO2024254820A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/40—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers
    • H04R1/403—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers loud-speakers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S1/00—Two-channel systems
    • H04S1/002—Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/34—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means
    • H04R1/345—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means for loudspeakers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers
    • H04R3/12—Circuits for transducers for distributing signals to two or more loudspeakers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R5/00—Stereophonic arrangements
    • H04R5/02—Spatial or constructional arrangements of loudspeakers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S2400/00—Details of stereophonic systems covered by H04S but not provided for in its groups
    • H04S2400/05—Generation or adaptation of centre channel in multi-channel audio systems

Definitions

  • the inventive subject matter generally relates to signal processing. More particularly, the inventive subject matter relates to a method for reproducing a constant sound field and a speaker apparatus therefor.
  • An audio signal is a carrier of regular sound wave frequency and amplitude change information.
  • Regular audio may be represented by a sound wave or a sine wave.
  • the sine wave includes three important parameters: frequency, amplitude, and phase, which also characterize the audio signal. Taking music as an example, people’s perception of sound frequency is expressed as pitch. A higher pitch corresponds to a higher frequency.
  • the amplitude reflects the energy magnitude of a signal.
  • a high-amplitude waveform signal has a larger volume, and a low-amplitude waveform has a quieter sound.
  • Dual-channel stereo can simulate the binaural effect to include directional information in the audio signal, and simulate the different gains and delays of a sound source from different positions to the left and right ears, enabling people to distinguish the sound source from different directions, thus obtaining a sense of presence.
  • audio signals are converted into sound through speakers.
  • the speaker converts the audio power signal within a certain range into audible sound with low distortion and enough sound pressure level through energy conversion, thus attempting to reproduce the sound field.
  • people have typically used axial frequency response curves to depict speakers.
  • the off-axis performance of speakers can have an impact on sound quality and subjective listening experience. Based on this, when using a mono speaker to reproduce stereo sound, a sweet spot can be limited on axis.
  • a small sweet spot may be limited around an axis, while a comb filtering issue caused by coherence between the left and right channels of the stereo exists when off axis.
  • a method for reproducing a constant sound field comprises a step of reproducing, via a woofer, low-frequency audio below a first crossover point from a left channel input and a right channel input.
  • the method further comprises a step of reproducing, via a tweeter unit, high-frequency audio above the first crossover point with constant frequency responses in all directions.
  • the tweeter unit may be configured to reproduce a constant sound field using a constant sound field algorithm with digital signal processing (DSP) in a frequency range above the first crossover point and below a second crossover point as well as with acoustic processing combined with the DSP in the frequency range above the second crossover point.
  • DSP digital signal processing
  • a speaker apparatus for reproducing a constant sound field.
  • the speaker apparatus comprises a woofer configured to reproduce low-frequency audio below a first crossover point from a left channel input and a right channel input.
  • the speaker apparatus further comprises a tweeter unit configured to reproduce high-frequency audio with constant frequency responses in all directions.
  • the tweeter unit may be configured to reproduce a constant sound field using a constant sound field algorithm with digital signal processing (DSP) in a frequency range above the first crossover point and below a second crossover point as well as with acoustic processing combined with the DSP in the frequency range above the second crossover point.
  • DSP digital signal processing
  • FIG. 2A illustrates a front view of a speaker apparatus for reproducing a constant sound field, in accordance with the one or more embodiments of the inventive subject matter
  • FIG. 2B illustrates the top view of the speaker apparatus of FIG. 2A for reproducing a constant sound field, in accordance with the one or more embodiments of the inventive subject matter
  • FIG. 3 shows a block diagram with audio chains using a CSF algorithm to achieve a constant sound field reproduction through DSP and acoustic processing, in accordance with the one or more embodiments of the inventive subject matter;
  • FIG. 4 illustrates an exemplary energy distribution map of the speaker apparatus for reproducing a constant sound field, optimized for interference by a three-horn combination structure in the high-frequency range, in accordance with the one or more embodiments of the inventive subject matter;
  • FIG. 5A illustrates an exemplary directivity comparison diagram for reproducing the frequency response of a sound field in speaker devices of different design tweeter combination structures, in accordance with the one or more embodiments of the inventive subject matter
  • FIG. 5B illustrates an exemplary directivity comparison diagram for reproducing the frequency response of a sound field in speaker devices of different design tweeter combination structures using the CSF algorithm, in accordance with the one or more embodiments of the inventive subject matter.
  • FIG. s6A and 6B illustrate exemplary comparison diagrams of the normalized audio frequency responses at various angles and directions in the sound field reproduced by the mono speaker and a CSF feature speaker, respectively, including the comparison data of the CSF speaker to the similar dimension of the mono speaker, in accordance with the one or more embodiments of the inventive subject matter.
  • the directivity of a speaker system refers to the spatial distribution of the sound pressure it radiates. At low frequencies, a dimension of its radiation surface is much smaller than the wavelength of the radiated sound wave, and the speaker system can be regarded as a point source, with its radiation being directionless. But as the frequency increases, the wavelength of sound waves becomes shorter. When the wavelength is equal to or less than the dimension of the radiation surface, the radiation phase of the speaker system exhibits obvious directivity, that is, the radiation sound pressure at different angles varies at the same distance. The larger the size and the higher the frequency, the stronger its directivity. Conversely, the smaller the size and the lower the frequency, the wider its directivity. Therefore, the directivity of the speaker system is related to two factors: frequency and the dimension of the radiation surface.
  • the audio frequency audible for human ears is between 20Hz and 20kHz.
  • the coherence may be significant.
  • the tweeter unit of the speaker apparatus can be designed to compensate for the attenuation in off-axis directions of the sound field by digital signal processing and/or acoustic processing, to achieve a uniform and consistent sound field in all radiation directions of the speaker apparatus.
  • FIG. 1 illustrates an exemplary flowchart 100 of the method for reproducing a constant sound field (CSF) according to one or more embodiments of the present inventive subject matter.
  • the method starts from step S110.
  • a speaker apparatus may be arranged with a woofer unit for playback of low-frequency audio and a tweeter unit for playback of high-frequency audio of a stereo input.
  • the woofer unit may be arranged with a woofer, for example, facing towards the front of the speaker apparatus, while the tweeter unit may be designed to reproduce a Hi-Fi sound field with uniform and constant frequency responses in all directions.
  • the tweeter unit in one or more embodiments of the present inventive subject matter may be designed as a tweeter combination structure with several tweeters to support several channels.
  • the tweeter unit may be implemented by multiple horns facing in different directions within a 180-degree radiation range in front of the speaker apparatus, and each horn may correspond to one channel of the tweeter combination structure.
  • the off-axis arranged horns may be expected to compensate for frequency response attenuations in the off-axis directions of the sound field.
  • the off-axis arranged horns may expand the sweet spot. Accordingly, at least three channels are required for the tweeter combination structure. In principle, a larger sweet spot can be obtained by increasing the number of channels.
  • One or more embodiments of the present inventive subject matter will be explained with the example of the 3-horn array tweeter combination structure.
  • FIG. 2A illustrates a front view 200 of the speaker apparatus 210 for reproducing a constant sound field according to one or more embodiments of the present inventive subject matter.
  • the speaker apparatus includes a woofer 220 located below and set towards the axial direction to reproduce low-frequency audio, and a tweeter unit located above and including three tweeters 230, 240, 250 facing in different off-axis directions to reproduce high-frequency audio.
  • the three tweeters 230, 240, 250 are arranged in parallel.
  • a center tweeter 240 may be arranged on axis and oriented towards the axial direction, a left arranged tweeter 230 may be oriented towards the left off-axis direction, and a right arranged tweeter 250 may be oriented towards the right off axis direction.
  • the center tweeter 240 may be considered as the tweeter facing to the 0-degree direction of the sound field, wherein an original sweet spot is located.
  • the left and right tweeters 230, 250 are arranged towards the left and right at a certain angle apart from the axially oriented center tweeter 240.
  • the frequency response in the left off-axis directions can be compensated by the left tweeter 230 facing to the left, while the frequency response in the right off axis directions can be compensated by the right tweeter 240 facing to the right.
  • the speaker apparatus 210 with the tweeter combination structure composed of these three tweeters 230, 240, 250, as well as the one woofer 220 can significantly expand the sweet spot and achieve a complete constant sound field.
  • FIG. 2B illustrates the top view 200’ of the speaker apparatus 210 of FIG. 2A for reproducing a constant sound field according to one or more embodiments of the present inventive subject matter.
  • the left and the right tweeters 230’, 250’ are arranged towards the left and right each at an angle of 60 degrees apart from the axially oriented center tweeter 240’ . It may be expected that the sweet spot may be expanded to 120 degrees in the sound field.
  • the woofer usually has a wide directivity in low frequency range. Due to such inconspicuous directivity features of the woofer, the speaker apparatus equipped with only one woofer may achieve a good low-frequency response in the sound field. Those skilled in the art may understand that low frequency audio can be filtered out by using a low pass filter and then be fed to the one woofer for playback.
  • the low-frequency audio below a crossover point can be filtered and fed to the woofer.
  • the crossover point for distinguishing the audio between the woofer and the tweeter unit may be set as a first crossover point f c1 .
  • the first crossover point is set at 2kHz.
  • the channel output with the low-frequency audio to be fed to the woofer can be simply described as an audio chain, which describes all the processing from the channel input to output, as by filtering the left and right channel inputs L in , R in , through a low-pass filter and down-mixing into one channel output to the woofer.
  • the audio chain for the woofer can be expressed as: LPF 1 (L in +R in ) (1)
  • L in represents the left channel input and R in , represents the right channel input;
  • LPF 1 is a low-pass filter of the first crossover point f c1 . Therefore, the left and right channel inputs L in , R in , are filtered and output through a low-pass filter LPF 1 , and the filtered left and right channel inputs below the first crossover point are mixed, LPF 1 (L in +R in ) , and fed to the woofer for playback, at S120 of FIG. 1.
  • the first crossover point f c1 is set at 2kHz.
  • the filtered audio signals below 2kHz are to be fed to the woofer. Due to the fact that the woofer audio does not require the processing with the CSF algorithm in one or more embodiments of the present inventive subject matter, this part is not illustrated in following FIG. 3 which is the focus of the CSF algorithm for processing the high-frequency audio above the first crossover point to be fed to the tweeter unit for playback.
  • FIG. 3 shows a block diagram 300 with audio chains using the CSF algorithm to achieve a constant sound field reproduction through DSP and acoustic processing, in accordance with the one or more embodiments of the inventive subject matter.
  • a dual-channel stereo may be input into the speaker apparatus, which includes a left channel input 310, L in , and a right channel input 312, R in .
  • the left and right channel inputs 310, 312 firstly enter the pre-equalizer 320 to be separated into various frequencies.
  • the pre-equalizer 320 comprises filters that, for example, may filter out high-frequency audio to be fed to the tweeter unit.
  • a high-pass filter, HPF 1 set to the first crossover point may filter and output the high-frequency audio.
  • the filtered high-frequency audio shall be processed by using the CSF algorithm as channel outputs for the tweeter combination structure, and then fed to each of the tweeters in the tweeter unit for playback, accordingly.
  • the method provided in the present inventive subject matter may be applied to this part of the audio processing for tweeters.
  • the center tweeter 240’ is oriented axially at 0 degree of the sound field where the sweet spot of the sound field is located. It is possible for the center tweeter 240’ to directly playback a center channel output down-mixed from the left and right channel inputs, L in +R in . Therefore, referring to FIG. 3, the center channel output 362 to be fed to the center tweeter may be described as an audio chain as by high-pass filtering the left channel input 310, L in , the right channel input 312, R in , and the down-mixed 352 the filtered left and right channel inputs L in +R in into one center channel output 362 for the center tweeter. Namely, the audio chain for the center channel output 362 can be expressed as: HPF 1 (L in +R in ) (2)
  • HPF 1 is a high pass filter set of the first crossover point f c1 , which is at 2kHz, in the example.
  • the left and right tweeters oriented towards off-axis directions may compensate for the attenuation of the frequency response beyond the original sweet spot, while further addressing the sound field halo caused by the acoustic coherence therebetween.
  • adding appropriate inverted right and left channel inputs to each audio chain of the left and right channels, respectively, may enable the channel outputs to cancel out with each other.
  • an inverted right channel input, invert (R in ) may be appropriately down-mixed therein, for cancelling the sound from the right channel by utilizing the coherence between different channels.
  • an inverted left channel input, invert (L in ) may be appropriately down-mixed therein, for cancelling the sound from the left channel.
  • the channel processing may also be performed by depending on the frequencies.
  • the whole high-frequency audio, above the first crossover point will undergo the DSP processing to achieve the reproduction of a constant sound field.
  • acoustic processing may be combined into the design of the tweeter unit to enable the frequency responds curve of the reproduced constant sound field to be more uniformed. Therefore, a second crossover point can be set thereat in the left and right DSP module 330, 332.
  • the directivity of high-frequency audio for the tweeter unit can be solved though the DSP, and acoustic processing shall be additionally adopted for the high-frequency audio above the second crossover point, to enhance the uniformity of high-frequency directivity.
  • the high-frequency audio between the first crossover point and the second crossover point may be processed thought DSP; and the high-frequency audio above the second crossover point will be processed by the DSP combining acoustic processing, with reference to S130 of FIG. 1.
  • the inverted right channel input to be down-mixed into the left and right channel may be adjusted by applying with gains and/or delays in the left and right DSP module 330, 332.
  • the gains and delays can be applied based on a uniformity of the left and right channel frequency response and the balance of sound pressure level, to achieve a constant sound field.
  • the gains and delays can be applied according to the frequencies. For example, a first set of gain G 1 and delay D 1 may be applied in the range from the first crossover point f c1 to a second crossover point f c2 , while a second set of gain G 2 and delayD 2 may be applied above the second crossover point f c2 .
  • the appropriate inverted left channel input 340 is processed in the left DSP module 330 and then output therefrom.
  • the DSP processing in the left DSP module 330 shall be as: LPF 2 [D 1 (invert (L in ) *G 1 ) ] , for f c1 ⁇ f ⁇ f c2 (3) and HPF 2 [D 2 (invert (L in ) *G 2 ) ] , for f ⁇ f c2 (4)
  • the audio chain of the right channel 360 to the right tweeter can be described by down-mixing 350 the right channel input with the appropriate inverted left channel input 340 applying with different gains G 1 , G 2 and delays D 1 , D 2 corresponding to various frequencies, i.e., the audio chain for the right channel output 360 can be expressed as: HPF 1 ⁇ LPF 2 [D 1 (invert (L in ) *G 1 ) +R in ] +HPF 2 [D 2 (invert (L in ) *G 2 ) +R in ] ⁇ (5)
  • L in represents left channel input and R in represents right channel input; invert(L in ) represents the phase-inverted left channel input; HPF 1 is a high pass filter set of the first crossover point f c1 ; LPF 2 is a low-pass filter set of the second crossover point f c2 ; HPF 2 is a high pass filter set of the second crossover point f c2 ; D 1 and G 1 represent the delay and gain applied between the first and the second crossover point, f c1 ⁇ f ⁇ f c2 , respectively; and D 2 and G 2 represent the delay and gain applied above the second crossover point, f ⁇ f c2 , respectively.
  • the appropriate inverted right channel input 342 is processed in the right DSP module 332 and then output therefrom, which shall be as: LPF 2 [D 1 (invert (R in ) *G 1 ) ] , for f c1 ⁇ f ⁇ f c2 (6) HPF 2 [D 2 (invert (R in ) *G 2 ) ] , for f ⁇ f c2 (7)
  • the audio chain of the left channel 364 to the left tweeter can be described by down-mixing 354 the left channel input 310 with the appropriate inverted right channel input 342 applying with different gains G 1 , G 2 and delays D 1 , D 2 corresponding to various frequencies, i.e., the audio chain for the left channel output 364 can be expressed as: HPF 1 ⁇ LPF 2 [D 1 (invert (R in ) *G 1 ) +L in ] +HPF 2 [D 2 (invert (R in ) *G 2 ) +L in ] ⁇ (8)
  • L in represents left channel input and R in represents right channel input; invert (R in ) represents the phase-inverted right channel input; HPF 1 is a high pass filter set of the first crossover point f c1 ; LPF 2 is a low-pass filter set of the second crossover point f c2 ; HPF 2 is a high pass filter set of the second crossover point f c2 ; D 1 and G 1 represent the delay and gain applied between the first and the second crossover point, f c1 ⁇ f ⁇ f c2 , respectively; and D 2 and G 2 represent the delay and gain applied above the second crossover point, f ⁇ f c2 , respectively.
  • the appropriate inverted right channel input 342, D 1 (invert (R in ) *G 1 ) for f c1 ⁇ f ⁇ f c2 , and D 2 (invert (R in ) *G 2 ) for f ⁇ f c2 both have the coherence with the right channel input R in from the right channel, and the coherent cancellation may occur therebetween. Accordingly, the sound between the left and right channel outputs may be cancelled out with each other.
  • the processed high-frequency audio of the three channel outputs may be fed to the right, center and left tweeters 250, 240, 230 of FIG. 2A in the tweeter unit, where acoustic speaker design may be performed in acoustic processing module 380, and then to be converted into sound 390 for playback, accordingly. This step is described in S140 of FIG. 1.
  • the second frequency point f c2 thus may be at 7kHz. There may be strong coherence between horns below 7kHz. Above 7kHz, the coherence may be not as strong, instead with the stronger directivities.
  • the delays, D 1 , D 2 set in the audio chain, as well as the gains, G 1 , G 2 can be adjusted according to the reproduced frequency response curve and tuning of the sound field, so that the entire sound field has high fidelity and uniform frequency response effect.
  • the gain and delay in the left and right audio chains can be the same or different.
  • the tweeter combination structure of the tweeter unit is designed as a horn array including three horns to adapt to the audio chains.
  • Horn is a typical electro-acoustic device with the main frequency of 2kHz to 20kHz, with the segmented frequency at the second crossover point of 7kHz. Above 7kHz, the coherence of the reproduced sound field may be not as strong, instead with the stronger directivities. It may be desirable to introduce the Acoustic Processing to compensate for such sharp directivities in high-frequency areas above the second crossover point.
  • the tweeter combination structure of the tweeter unit may be processed in the acoustic processing module 380, for example, by changing the dimensions and/or angular arrangements of the horn array, such as shown in FIG. 2B, where the left and right horns each may be arranged at an angle of 60 degrees from the center horn, thereby expanding the sweet spot of the reproduced sound field to 120 degrees.
  • more than three horns may be used, and be arranged in other orientations. More horns and channel outputs may achieve a larger sweet spot, in practically.
  • a horn typically includes a compression driver for emitting sound plus a horn throat, and a horn opening.
  • a compression driver for emitting sound plus a horn throat, and a horn opening.
  • the shapes of the combined horns can be designed.
  • the use of catenary, hyperbolic, exponential horns, etc. may be given priority.
  • other curves being as smooth as possible can be used to define the horn, and try to ensure a smooth transition from throat to mouth of the horn.
  • the tweeter unit processed in the acoustic processing module 380 may be configured by modified the transducer of the speaker.
  • full-range speakers may be adapted for the transducer design.
  • the “full range” connotes the speaker that covers the entire auditory range of the human ears, and naturally carries directivity characteristics.
  • the high-frequency directivity characteristics of a single full-range speaker can be equivalent to the tweeter with horn, enabling adapted to the multiple channel outputs in non-coherence of the high frequency range and overcoming the issues with sharp directivity in the high frequency range. So the two may be replaced with each other.
  • the tweeter unit processed in the acoustic processing module 380 may be further include waveguide design.
  • Acoustic waveguide can be complex acoustic structural devices, which can be able to emit sound waves directionally and may play an important role in sound tuning.
  • the design of waveguides may be very complicated. the usage of sound field simulation tools may be helped for designing the waveguide, thereby enhancing the uniformity of the sound field and facilitating to design a constant sound field speaker.
  • the audio chains such as the gains and the delays, may be adjusted, as well as the tweeter unit configuration, such as the shape and the number of horns therein, may be modified.
  • the transducer and/or the waveguide design may also be applied, to achieve a constant sound field.
  • FIG. 4 illustrates an exemplary energy distribution map 400 of the speaker apparatus for reproducing a constant sound field, optimized for interference by a three-horn combination structure in the high-frequency range, in accordance with the one or more embodiments of the inventive subject matter.
  • the lighter grayscale in the energy distribution map the higher energy distributed herein. It can be seen from FIG. 4 that, within the whole 180-degree radiation range in the figure the overall energy distribution is relatively uniform in the sound field reconstructed by the three horns 430, 440, 450 facing on axis at 0 degrees, left off axis at 60 degrees, and right off axis at 60 degrees, respectively.
  • FIG. 5A illustrates an exemplary directivity comparison diagram 500 for reproducing the frequency response of a sound field in speaker devices of different design tweeter combination structures
  • FIG. 5B illustrates an exemplary directivity comparison diagram 500’ for reproducing the frequency response of a sound field in speaker devices of different design tweeter combination structures using the CSF algorithm, in accordance with the one or more embodiments of the inventive subject matter.
  • the dotted line represents the directivity line 510, 510’ formed by a mono speaker
  • the curve depicted by the dashed line represents the directivity line 520, 520’ formed by stereo speaker (dual channel) .
  • FIG. s5A and 5B depict the acoustic performances of CSF feature speakers.
  • the CSF feature comes from the designed horn array.
  • FIG. 5B shows the acoustic performance of the CSF featured system including the usage of the CSF algorithm.
  • FIG. s 6A and 6B illustrate exemplary comparison diagrams 600, 600’ of the normalized audio frequency responses at various angles and directions in the sound field reproduced by the mono speaker and the CSF feature speaker, respectively, including the comparison data of the CSF speaker to the similar dimension of the mono speaker, in accordance with the one or more embodiments of the inventive subject matter.
  • solid line 610 depicts the frequency response curve of the sound field reproduced by a mono speaker in the 0- degree axial direction
  • dashed line 620 depicts the frequency response curve of the sound field reproduced by the mono speaker in the 30 degree off axis direction
  • dotted lines 630 depicts the frequency response curve of the sound field reproduced by the mono speaker in the 60 degree off axis direction.
  • solid line 640 depicts the frequency response curve of the sound field reproduced by a CSF feature speaker in the 0-degree axial direction
  • dashed line 650 depicts the frequency response curve of the sound field reproduced by the CSF feature speaker in the 30 degree off axis direction
  • dotted lines 660 depict the frequency response curve of the sound field reproduced by the CSF feature speaker in the 60 degree off axis direction, respectively.
  • the frequency response curves in the 0 degree direction of the sound field axis are both flat for the CSF feature speaker and mono speaker as normalization.
  • the frequency response curves 650, 660 of the CSF feature speaker are relatively flatter in shape, and its frequency response curves in all directions are much closer to achieve constant, than those 620, 630 of the mono speaker. Accordingly, frequency responses of the CSF feature speaker in all directions both on axis and off axis may be more consistent and more constant than those of the mono speaker.
  • the tweeter combination structure with horns can be adjusted according to speaker configuration. It is preferable to uniformize the speaker directivity depending on the performance of transducer and CSF design target.
  • the tweeter unit can be a designable tweeter combination structure equipped with a horn array, including horns oriented in different directions in space to obtain a reproducible sound field with constant frequency responses within the entire radiation range of the speaker apparatus. Additional or alternative designs for the tweeter unit, such as in designing transducers and waveguides of the speaker may also achieve the similar acoustic effects.
  • the present inventive subject matter provides a method for designing a constant sound field speaker, which utilizes a CSF algorithm to process audio chains fed to the tweeter unit.
  • the CSF feature speaker apparatus can be applied with multi-channel configuration with more than or equal to 3 channels, and either 1-way, 2-ways, 3-ways or more ways speaker configurations, wherein the horns adopted in the tweeter unit can be adjusted according to speaker configuration, which can be optional depending on the performance of the transducer and the CSF design target.
  • a constant sound filed can be achieved by using digital signal processing and acoustic processing.
  • the advantages of the method may include that all details in stereo music can be maintained; enlarged sweet spots in the entire sound field may be achieved; and the correct sound stage in sweet spot range may be delivered.
  • the computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium.
  • the computer-readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing.
  • the computer-readable storage medium may include, for example: an electrical connection with one or more wires, portable computer floppy disks, hard disks, random access memory (RAM) , read-read-only memory (ROM) , erasable programmable read only memory (EPROM or flash memory) , optical fibers, portable compact disc read only memory (CD-ROM) , optical storage devices, magnetic storage devices, or any suitable combinations of the foregoing.
  • the computer-readable storage medium may be any tangible medium that can include or store a program for use by or in connection with an instruction execution system, apparatus, or device.
  • references in the present inventive subject matter to the method for reproducing a constant sound field include the following content:
  • the present inventive subject matter provides a method for reproducing a constant sound field, comprising steps of:
  • the tweeter unit may be configured to reproduce a constant sound field using a constant sound field algorithm with digital signal processing (DSP) in a frequency range above the first crossover point and below a second crossover point as well as with acoustic processing combined with the DSP in the frequency range above the second crossover point.
  • DSP digital signal processing
  • the tweeter unit can be configured as a tweeter combination structure comprising at least three tweeters, wherein high-frequency audio fed as at least three audio chains up-mixed from the left channel input and the right channel input into the at least three tweeters, correspondingly.
  • Item 3 The method of item 1 or 2, wherein the at least three audio chains comprise at least one left audio chain and at least one right audio chain, and wherein the DSP comprises down-mixing the left channel input and the inverted right channel input into at least one left audio chain, and down-mixing the right channel input and the inverted left channel input into the at least one right audio chain.
  • Item 4 The method of any of items 1-3, wherein the at least three audio chains comprise a center audio chain which is down mixed by the left channel input and the right channel input.
  • Item 5 The method of any of items 1-4, wherein the first crossover point is set to be the crossover point between the woofer and the tweeter unit, and wherein the second crossover point is set to be the segmented frequency of the tweeter unit.
  • Item 6 The method of any of items 1-5, wherein the at least three audio chains each may be applied for delays and/or gains, and the delays and/or the gains may be set with different values above and below the second crossover point in each of the at least three audio chains.
  • Item 8 The method of any of items 1-7, wherein the tweeter unit can be configured by arranging number, orientations and shapes of horns in the horn array.
  • Item 9 The method of any of items 1-8, wherein the tweeter unit may be configured by arranging a full-range speaker, into which the at least three audio chains are fed, respectively, for reproducing the constant sound field.
  • Item 10 The method of any of items 1-9, wherein the speaker apparatus comprises a waveguide, and the tweeter unit may be designed using sound field simulation tools to design the waveguide, to reproduce the constant sound field.
  • the present inventive subject matter further provides a speaker apparatus for reproducing a constant sound field, comprising:
  • a woofer configured to reproduce low-frequency audio below a first crossover point from a left channel input and a right channel input
  • a tweeter unit configured to reproduce high-frequency audio with constant frequency responses in all direction
  • the tweeter unit may be configured to reproduce a constant sound field using a constant sound field algorithm with digital signal processing (DSP) in a frequency range above the first crossover point and below a second crossover point as well as with acoustic processing combined with the DSP in the frequency range above the second crossover point.
  • DSP digital signal processing
  • Item 12 The speaker apparatus of item 11, wherein the tweeter unit further comprises a tweeter combination structure comprising at least three tweeters, wherein high-frequency audio is fed as at least three audio chains up-mixed from the left channel input and the right channel input into the at least three tweeters, correspondingly.
  • a tweeter combination structure comprising at least three tweeters, wherein high-frequency audio is fed as at least three audio chains up-mixed from the left channel input and the right channel input into the at least three tweeters, correspondingly.
  • Item 13 The speaker apparatus of item 11 or 12, wherein the at least three audio chains comprise at least one left audio chain and at least one right audio chain, and wherein the DSP comprises down-mixing the left channel input and an inverted right channel input into at least one left audio chain, and down-mixing the right channel input and an inverted left channel input into the at least one right audio chain.
  • Item 14 The speaker apparatus of any of items 11-13, wherein the at least three audio chains comprise a center audio chain which is down mixed by the left channel input and the right channel input.
  • Item 15 The speaker apparatus of any of items 11-14, wherein the first crossover point is set to be a crossover point between the woofer and the tweeter unit, and wherein the second crossover point is set to be a segmented frequency of the tweeter unit.
  • Item 16 The speaker apparatus of any of items 11-15, wherein the at least three audio chains each may be applied for delays and/or gains, and the delays and/or the gains may be set with different values above and below the second crossover point in each of the at least three audio chains.
  • Item 17 The speaker apparatus of any of items 11-16, wherein the tweeter unit may be implemented by a horn array.
  • Item 18 The speaker apparatus of any of items 11-17, wherein the tweeter unit can be configured by arranging number, orientations and shapes of horns in the horn array.
  • Item 19 The speaker apparatus of any of items 11-18, wherein the tweeter unit may be configured by arranging a full-range speaker, into which the at least three audio chains are fed, respectively, for reproducing the constant sound field.
  • Item 20 The speaker apparatus of any of items 11-19, wherein the speaker apparatus comprises a waveguide, and the tweeter unit may be designed using sound field simulation tools to design the waveguide, to reproduce the constant sound field.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Circuit For Audible Band Transducer (AREA)

Abstract

L'invention concerne un procédé permettant de reproduire un haut-parleur à champ constant, qui comprend les étapes consistant à reproduire un audio basse fréquence avec des entrées de canal gauche et droite en dessous d'un premier point de croisement au moyen d'un haut-parleur de graves. Ce procédé comprend également les étapes consistant à reproduire un audio haute fréquence au-dessus du premier point de croisement dans toutes les directions avec des réponses en fréquence constante au moyen d'une unité d'aigus. L'unité d'aigus peut être configurée en utilisant un algorithme CSF avec un DSP au-dessus du premier point de croisement et en dessous d'un second point de croisement. Et l'unité peut être configurée en utilisant l'algorithme CSF avec un traitement acoustique combiné au DSP, pour reproduire le champ sonore constant. L'invention concerne également un appareil haut-parleur permettant de reproduire le champ sonore constant à l'aide de ce procédé.
PCT/CN2023/100411 2023-06-15 2023-06-15 Procédé permettant de concevoir un haut-parleur à champ sonore constant Ceased WO2024254820A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
PCT/CN2023/100411 WO2024254820A1 (fr) 2023-06-15 2023-06-15 Procédé permettant de concevoir un haut-parleur à champ sonore constant
CN202380099423.0A CN121312153A (zh) 2023-06-15 2023-06-15 设计恒定声场扬声器的方法
EP23745382.4A EP4728755A1 (fr) 2023-06-15 2023-06-15 Procédé permettant de concevoir un haut-parleur à champ sonore constant

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2023/100411 WO2024254820A1 (fr) 2023-06-15 2023-06-15 Procédé permettant de concevoir un haut-parleur à champ sonore constant

Publications (1)

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WO2024254820A1 true WO2024254820A1 (fr) 2024-12-19

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EP (1) EP4728755A1 (fr)
CN (1) CN121312153A (fr)
WO (1) WO2024254820A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040218764A1 (en) * 1998-10-14 2004-11-04 Kentech Interactive Point source speaker system
WO2007079225A2 (fr) * 2005-12-30 2007-07-12 Gaki Audio, Llc Système de haut-parleurs biplan avec sortie audio en phase dans le temps
US20090310808A1 (en) * 2008-06-17 2009-12-17 Harman International Industries, Incorporated Waveguide
US20110135119A1 (en) * 2009-09-11 2011-06-09 Ickler Christopher B Automated customization of loudspeakers
US8175304B1 (en) * 2008-02-12 2012-05-08 North Donald J Compact loudspeaker system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040218764A1 (en) * 1998-10-14 2004-11-04 Kentech Interactive Point source speaker system
WO2007079225A2 (fr) * 2005-12-30 2007-07-12 Gaki Audio, Llc Système de haut-parleurs biplan avec sortie audio en phase dans le temps
US8175304B1 (en) * 2008-02-12 2012-05-08 North Donald J Compact loudspeaker system
US20090310808A1 (en) * 2008-06-17 2009-12-17 Harman International Industries, Incorporated Waveguide
US20110135119A1 (en) * 2009-09-11 2011-06-09 Ickler Christopher B Automated customization of loudspeakers

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EP4728755A1 (fr) 2026-04-22
CN121312153A (zh) 2026-01-09

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