EP3697108A1 - Système audio de voiture - Google Patents

Système audio de voiture Download PDF

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Publication number
EP3697108A1
EP3697108A1 EP19157678.4A EP19157678A EP3697108A1 EP 3697108 A1 EP3697108 A1 EP 3697108A1 EP 19157678 A EP19157678 A EP 19157678A EP 3697108 A1 EP3697108 A1 EP 3697108A1
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EP
European Patent Office
Prior art keywords
loudspeaker
channel
sound
channels
midrange
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19157678.4A
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German (de)
English (en)
Inventor
Tomasz Twardowski
Grzegorz Golabek
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Aptiv Technologies Ltd
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Aptiv Technologies Ltd
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Publication date
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Priority to EP19157678.4A priority Critical patent/EP3697108A1/fr
Publication of EP3697108A1 publication Critical patent/EP3697108A1/fr
Withdrawn legal-status Critical Current

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    • 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
    • H04R2499/00—Aspects covered by H04R or H04S not otherwise provided for in their subgroups
    • H04R2499/10—General applications
    • H04R2499/13—Acoustic transducers and sound field adaptation in vehicles
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S2420/00—Techniques used stereophonic systems covered by H04S but not provided for in its groups
    • H04S2420/01—Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S5/00—Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation 
    • H04S5/02—Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation  of the pseudo four-channel type, e.g. in which rear channel signals are derived from two-channel stereo signals

Definitions

  • the present disclosure relates to a method for operating a car audio system comprising a loudspeaker setup connected to control means for reproducing audio information, with said loudspeaker setup comprising a left loudspeaker arrangement and a right loudspeaker arrangement activated by said control means via a left channel and a right channel, respectively.
  • the disclosure further relates to a respective car audio system in particular for carrying out the method.
  • Previous car audio systems require left and right loudspeakers activated by left and right channels for providing a left/right sound directivity, and additional front and rear loudspeakers activated by additional front and rear channels for providing a front-rear sound directivity. All loudspeakers are shared by all car users. For balancing the sound level between front and rear channels a dedicated fader is necessary. For the front/rear fader functionality only gain is changed on the front/rear channels.
  • the left/right sound directivity together with the front/rear sound directivity should be achieved only by left/right loudspeakers activated only by the left/right channels.
  • the present disclosure provides a method with the features of claim 1 and a car audio system with the features of claim 10. Embodiments of the method and of the car audio system are given in the subclaims, the description and the drawings.
  • the present disclosure is directed at a method for operating a car audio system comprising a loudspeaker setup connected to control means for reproducing audio information, with said loudspeaker setup comprising a left loudspeaker arrangement and a right loudspeaker arrangement activated by said control means via a left channel and a right channel, respectively.
  • a fader function as to a rear/front audio directivity for the car occupants via only the left channel and right channel is generated by forming spectral subbands of the audio information by FIR filtering with fixed delay and adjustable by parameters such as gain, delays, edge frequencies in the subbands and/or the like, and/or by shaping the sound of the reproduced audio information by FIR filtering on the basis of Head Related Transfer Functions (HRTFs).
  • HRTFs Head Related Transfer Functions
  • a finite impulse response (FIR) filter is a filter whose impulse response is of finite duration, because it settles to zero in finite time.
  • the impulse response of an Nth order discrete-time FIR filter lasts exactly N+1 samples before it then settles to zero.
  • FIR filters can be discrete-time or continuous-time filters, and digital or analog.
  • a head-related transfer function is a response that characterizes how an ear receives a sound from a point in space. As sound strikes the listener, the size and shape of the head, ears, ear channel, density of the head, size and shape of nasal and oral cavities, all transform the sound and effect how it is perceived, boosting some frequencies and attenuating others.
  • the HRTF responses of the human ear with varying location of the sound source are measured and collected in publicly available databases which can be used for the sound shaping by FIR filtering.
  • the method may comprise one or more of the following features: Said step of generating said fader function may comprise the activation of more than one loudspeaker by each of the two channels, and/or the activation of at least two loudspeakers of different frequency characteristics.
  • the step of generating a fader function by shaping the sound of the reproduced audio information by Head Related Transfer Functions comprises the use of average ear characteristics, optionally using average ear characteristics according to the KEMAR model.
  • the generation of said fader function may comprise the activation of more than one loudspeaker by each of the two channels.
  • the generation of said fader function may comprise the activation of at least two loudspeakers of different frequency characteristics.
  • the difference in the frequency characteristics in the loudspeakers connected to one channel is essential in particular in connection with the generation of said fader function by the formation of spectral subbands, since the respective space-frequency diversity of the loudspeaker setups can be exploited.
  • At least one tweeter loudspeaker and at least one midrange loudspeaker may be associated with each of the two channels.
  • the generation of said fader function by the formation of adjustable spectral subbands may comprise changing the frequency spectrum of a respective channel in order to balance the sound energy between the at least one tweeter loudspeaker and the at least one midrange loudspeaker associated with a respective channel.
  • Dedicated loudspeakers for the driver and passenger and at least one passenger may be associated with each of the two channels.
  • a tweeter loudspeaker and a midrange loudspeaker for the driver and a tweeter loudspeaker and a midrange loudspeaker for the at least one passenger may be associated with each of the two channels.
  • the generation of a fader function by shaping the sound of the reproduced audio information by Head Related Transfer Functions comprises the use of average ear characteristics, in particular average ear characteristics according to the KEMAR model.
  • the KEMAR database comprises average Head Related Transfer Functions (HRTFs) for a torso of a typical anatomy.
  • HRTFs Head Related Transfer Functions
  • each of the loudspeaker arrangements may comprise a subwoofer which is activated by the respective channel.
  • Said subwoofers may not be affected by a respective change of the frequency spectrum and/or a respective sound shaping and are used only for a delay compensation.
  • the present disclosure is directed at a car audio system comprising a loudspeaker setup connected to control means for reproducing audio information, with said loudspeaker setup comprising a left loudspeaker arrangement and a right loudspeaker arrangement activated by said control means via a left channel and a right channel.
  • the control means are laid out for generating a fader function as to a rear/front audio directivity for the car occupants via only the left channel and right channel by forming spectral subbands of the audio information by FIR filtering with fixed delay and adjustable by parameters such as gain, delays, edge frequencies in the subbands and/or the like, and/or by shaping the sound of the reproduced audio information by FIR filtering on the basis of Head Related Transfer Functions.
  • the generation of the fader function by forming spectral subbands of the audio information changes the spectrum on a common channel to balance sound energy especially between midrange and tweeter loudspeakers.
  • the source shaping results in a clear objective impression of a moving sound source.
  • the ear shaping exploits characteristics of the human ear, which is highly individual. It causes the subjective impression of sound source moving.
  • Embodiments of the car audio systems are given in the subclaims.
  • the car audio systems may be configured to carry out the method described herein and may further comprise one or more of the following features:
  • One or more loudspeakers may be configured to be activated by said fader function by each of the two channels.
  • at least two loudspeakers of different frequency characteristics may be configured to be activated by said fader function by each of the two channels.
  • At least one tweeter loudspeaker and at least one midrange loudspeaker may be associated with each of the two channels.
  • the generation of said fader function by the formation of adjustable spectral subbands may comprise changing the frequency spectrum of a respective channel in order to balance the sound energy between the at least one tweeter loudspeaker and the at least one midrange loudspeaker associated with a respective channel.
  • Dedicated loudspeakers for the driver and at least one passenger may be associated with each of the two channels, optionally with a tweeter loudspeaker and a midrange loudspeaker for the driver and a tweeter loudspeaker and a midrange loudspeaker for the at least one passenger being able to be associated with each of the two channels.
  • the generation of a fader function by shaping the sound of the reproduced audio information by Head Related Transfer Functions may comprise the use of average ear characteristics, optionally average ear characteristics according to the KEMAR model.
  • Each of the loudspeaker arrangements may comprise a subwoofer which is activated by the respective channel. Said subwoofers may not be affected by a respective change of at least one of the frequency spectrum and a respective sound shaping and are used only for a delay compensation.
  • Fig. 1 a typical conventional full loudspeaker setup for realizing a left/right audio directivity as well as the front/rear directivity is shown.
  • All loudspeakers of this conventional full loudspeaker setup are shared by all car users. Independent channels are provided for rear/front and left/right loudspeakers, i.e. a left channel and a right channel for the left/right audio directivity and separate front/rear channels for the front/rear audio directivity are necessary. Thus, a separate fader must be realized by balancing the sound level between the separate front and rear channels. With this typical conventional full loudspeaker setup only gain is changed on front/rear channels for realizing the front/rear fader functionality.
  • FIG. 2 to 12 Exemplary embodiments of a car audio system 10 are shown in Figs. 2 to 12 .
  • a respective car audio system 10 comprises a loudspeaker setup 12 connected to control means for reproducing audio information, with said loudspeaker setup 12 comprising a left loudspeaker arrangement 12 L and a right loudspeaker arrangement 12 R activated by said control means via a left channel 14 L and a right channel 14 R , respectively (cf. in particular Figs. 2, 3 and 8 ).
  • the control means of a respective car audio system 10 are laid out for generating a fader function as to a rear/front audio directivity for the car occupants via only the left channel 14 L and right channel 14 R by forming spectral subbands of the audio information by FIR filtering with fixed delay and adjustable by parameters such as gain, delays, edge frequencies in the subbands and/or the like (cf. for example Figs. 2 to 7 ), and/or by shaping the sound of the reproduced audio information by FIR filtering on the basis of Head Related Transfer Functions (cf. for example Figs. 8 to 12 ).
  • the generation of a fader function may comprise the activation of more than one loudspeaker by each of the two channels 14 L , 14 R , in particular at least two loudspeakers of different frequency characteristics (cf. for example Fig. 2 to 7 ).
  • the difference in the frequency characteristics in the loudspeakers connected two one channel is essential in particular in connection with the generation of said fader function by the formation of spectral subbands, since the respective space-frequency diversity of the loudspeaker setups can be exploited.
  • at least one tweeter loudspeaker and at least one midrange loudspeaker may be associated with each of the two channels 14 L , 14 R .
  • the generation of said fader function by the formation of adjustable spectral subbands may comprise changing the frequency spectrum of a respective channel 14 L , 14 R in order to balance the sound energy between the at least one tweeter loudspeaker and the at least one midrange loudspeaker associated with a respective channel 14 L , 14 R .
  • Dedicated loudspeakers for the driver and at least one passenger may be associated with each of the two channels 14 L , 14 R .
  • a tweeter loudspeaker and a midrange loudspeaker for the driver and a tweeter loudspeaker and a midrange loudspeaker for the at least one passenger may, e.g., be associated with each of the two channels 14 L , 14 R .
  • the generation of a fader function by shaping the sound of the reproduced audio information by Head Related Transfer Functions may comprise the use of average ear characteristics, in particular average ear characteristics according to the KEMAR model (cf. for example Fig. 11 ).
  • Each of the loudspeaker arrangements 12 L , 12 R may comprise a subwoofer which is activated by the respective channel 14 L , 14 R (cf., e.g., Fig. 2 ).
  • the subwoofers are not affected by a respective change or variation of the frequency spectrum and/or a respective sound shaping and used only for a delay compensation.
  • Fig. 2 shows a generic loudspeaker setup 12 comprising at least two loudspeakers of different frequency characteristics associated with a respective channel 14 L , 14 R .
  • Each of the left loudspeaker arrangement 12 L and the right loudspeaker arrangement 12 R connected to the left channel 14 L and right channel 14 R , respectively, comprises a tweeter loudspeaker on the front side of the car, a midrange loudspeaker and a subwoofer on the rear side.
  • the difference in the frequency characteristics of the loudspeakers connected to a respective channel is used for creating space-frequency sound diversity.
  • the front/rear sound directivity on the basis of the left/right channel setup is achieved by exploiting space-frequency diversity of the loudspeaker setup 12.
  • special subband channels corresponding to individual loudspeakers are created which can be operated like physical channels.
  • Fig. 3 depicts an exemplary loudspeaker setup 12 comprising at least two loudspeakers of different frequency characteristics associated with a respective channel 14 L ,14 R .
  • Dedicated speakers for the driver and a passenger are provided on the two channels 14 L and 14 R .
  • the loudspeaker setup 12 comprises nine loudspeakers including four front/tweeter loudspeakers 16, four midrange loudspeakers 18 and a subwoofer 20.
  • Two of the four front/tweeter loudspeakers 16, namely the front/tweeter loudspeakers 16 1 and 16 2 , and two of the four midrange loudspeakers 18, namely the midrange loudspeakers 18 1 and 18 2 , may, e.g., be provided for the driver, whereas the other two front/tweeter loudspeakers 16 3 and 16 4 and the other two midrange loudspeakers 18 3 and 18 4 may, e.g. be provided for the passenger.
  • the front/tweeter loudspeaker 16 1 and the midrange loudspeakers 18 1 provided for the driver and the front/tweeter loudspeaker 16 3 and the midrange loudspeaker 18 3 provided for the passenger may be connected to the left channel 14L.
  • the front/tweeter loudspeaker 16 2 and the midrange loudspeakers 18 2 provided for the driver and the front/tweeter loudspeaker 16 4 and the midrange loudspeaker 18 4 provided for the passenger may be connected to the right channel 14R.
  • a subwoofer 20 may be connected to both channels 14 L , 14 R .
  • the front/tweeter loudspeakers 16 and the midrange loudspeakers 18 may have partially overlapping frequency responses.
  • joint characteristics as shown in Fig. 6 are applied in the virtual fader implementation according to Fig. 3 .
  • Fig. 6 the left/right channel frequency response variation for a virtual fader according to Fig. 3 is shown.
  • Fig. 4 exemplary spectral subbands created by FIR filters implemented for the front/rear sound directivity in connection with the loudspeaker setup as shown in Fig. 3 are depicted
  • Fig. 5 shows exemplary responses of the respective speakers of the loudspeaker setup as shown Fig. 3 due to the spectral subbands A, B as shown in Fig. 4 .
  • FIG. 7 An exemplary structure of the sound processing of a digital signal processor (DSP) of the control means for forming spectral subbands for the loudspeaker setup according to Fig. 3 is shown in Fig. 7 .
  • DSP digital signal processor
  • Fig. 8 shows an exemplary structure of the sound processing of a digital signal processor (DSP) of the control means for forming spectral subbands for the generic left/right audio channel setup as shown in Fig. 2 .
  • DSP digital signal processor
  • Fig. 9 depicts a generic loudspeaker setup 12 for the sound shaping by FIR filtering on the basis of Head Related Transfer Functions (HRTFs) comprising at least one left loudspeaker and at least one right loudspeaker associated with the left channel 14 L and the right channel 14 R , respectively.
  • HRTFs Head Related Transfer Functions
  • this basic configuration there can be only two loudspeakers, namely one loudspeaker of the left loudspeaker arrangement 12 L connected to the left channel 14 L and another loudspeaker of the right loudspeaker arrangement 12 R connected to the right channel 14 R .
  • the front/rear sound directivity on the basic loudspeaker setup is achieved by the implementation of Head Related Transfer Functions (HRTFs).
  • HRTFs Head Related Transfer Functions
  • anatomical features of the human pinna act as a direction-dependent acoustic aperture. Acoustic waves from a particular direction reach the ear channel directly and via reflections at the rims of the cavities, said reflections having different path lengths.
  • Fig. 10 depicts exemplary HRTF FIR responses used for the sound shaping by FIR filtering on the basis of Head Related Transfer Functions (HRTFs). The perceived effect depends on how closely the HRTFs set match the characteristic of one's ear.
  • HRTFs Head Related Transfer Functions
  • a KEMAR database may give average HRTFs for a torso of a typical anatomy. For example, KEMAR ear2 in azimuth range ⁇ 50° and elevation -20° may be used.
  • Fig. 11 shows an exemplary structure of the sound processing of a digital signal processor (DSP) of the control means for the sound shaping by FIR filtering on the basis of Head Related Transfer Functions (HRTFs).
  • DSP digital signal processor
  • HRTFs Head Related Transfer Functions
  • HRTF FIR is varying with fader setting.
  • Neutral fader setting affects only delay.
  • the subwoofer channel is not affected, only delay is compensated.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Stereophonic System (AREA)
EP19157678.4A 2019-02-18 2019-02-18 Système audio de voiture Withdrawn EP3697108A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060280316A1 (en) * 2005-06-09 2006-12-14 Lear Corporation Audio system and method for controlling an audio system
US20110176684A1 (en) * 2005-12-28 2011-07-21 Yamaha Corporation Sound Image Localization Apparatus
US20130010970A1 (en) * 2010-03-26 2013-01-10 Bang & Olufsen A/S Multichannel sound reproduction method and device
EP2806663A1 (fr) * 2013-05-24 2014-11-26 Harman Becker Automotive Systems GmbH Génération de zones sonores individuelles dans une salle d'écoute

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060280316A1 (en) * 2005-06-09 2006-12-14 Lear Corporation Audio system and method for controlling an audio system
US20110176684A1 (en) * 2005-12-28 2011-07-21 Yamaha Corporation Sound Image Localization Apparatus
US20130010970A1 (en) * 2010-03-26 2013-01-10 Bang & Olufsen A/S Multichannel sound reproduction method and device
EP2806663A1 (fr) * 2013-05-24 2014-11-26 Harman Becker Automotive Systems GmbH Génération de zones sonores individuelles dans une salle d'écoute

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DANIEL WALLACE ET AL: "Developing an In-Car 3D Audio System using the latest Virtual Audio Methods", 13 June 2016 (2016-06-13), XP055607141, Retrieved from the Internet <URL:http://www.sea-acustica.es/fileadmin/Oporto16/165.pdf> [retrieved on 20190719] *

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