Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04S—STEREOPHONIC SYSTEMS 
  • H04S7/00—Indicating arrangements; Control arrangements, e.g. balance control
  • H04S7/30—Control circuits for electronic adaptation of the sound field
  • H04S7/301—Automatic calibration of stereophonic sound system, e.g. with test microphone
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R5/00—Stereophonic arrangements
  • H04R5/02—Spatial or constructional arrangements of loudspeakers
• • 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; DEAF-AID SETS; 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 
  • H04S2400/00—Details of stereophonic systems covered by H04S but not provided for in its groups
  • H04S2400/09—Electronic reduction of distortion of stereophonic sound systems

Definitions

• the stereophonic process makes it possible to obtain a continuous and homogeneous sound image from two point sources provided that the listener is located equidistant from these two sources.
• the difference in distance between the speakers and the listeners generates distortions of levels and acoustic phases between the 2 channels which deeply degrade the stereophonic reproduction by car.
• the present invention belongs to the category of bi-stereophonic methods.
• All of these methods recommend inverting the stereo phase in certain frequency bands in order to reduce the acoustic phase distortion between the channels and they differ mainly in the operating mode used.
• Inverting the stereophonic phase consists in applying a phase difference of 180 ° between the two channels, for example by inverting the phase of one of the two channels.
• phase distortion changes sign and its modulus becomes the 180 ° complement of the original distortion.
• the present invention is a novel method for improving automobile stereophonic reproduction in a real vehicle to obtain a better result than that obtained by known methods, and this by using the difference between the phase distortions at the two locations of listening.
• a microphone was placed at each listening position and a pink noise signal was successively applied to each left and right speaker.
• a signal is applied to the left speaker and the phase difference [ ⁇ 0 - ⁇ ⁇ ? ] 0 between the signal generated by the left microphone and the signal applied to the left speaker.
• a signal is applied to the right speaker and the phase difference [ ⁇ ⁇ ⁇ ⁇ . ";] ⁇ is measured between the signal generated by the microphone on the left and the signal applied to the right speaker. .
• the average phase distortion (average absolute values between 100 Hz and 1600 Hz) is 101 ° driver side and 116 ° passenger side a total of 217 ° an average of 108.5 °.
• the solid curve is the distortion of driver's side residual phase and the dotted curve is the distortion residual passenger side stage after application '' of a reversal of the phase of a channel according to the conventional method c at frequencies favoring the conductor, namely between 100 Hz and 315 Hz and between 1000 Hz and 1250 Hz.
• the residual distortions are 34 ° driver side and 62 ° passenger side a total of 96 ° and an average of 48 °.
• the first of the two main ideas of the present invention is to apply a specific treatment to the frequency bands for which [O c -0 0 ] G and [ ⁇ ⁇ - ⁇ ] ⁇ are not of the same sign.
• the necessary and sufficient condition to obtain a minimum of total distortion at a frequency 'for which the distortions on the right and on the left are not of the same sign is to apply a phase shift between the two channels that make them the same sign.
• the sum of the distortions obtained is then equal to the difference between the original distortions.
• ⁇ 0 ⁇ be the phase correction to be applied to the left channel to symmetrize the phase distortions. If symmetrization is possible ⁇ ⁇ must be the solution of 1 equation:
• Equation 4 has a solution that is:
• the curves in fine lines are the original distortions and the thick curve symmetrized phase distortion that stands out at an average of 66 °.
• the fine-line curves are the left and right distortions obtained by the traditional method, that is to say the curves of FIG. 2, and the thick line curve is the residual distortion after symmetrization and inversion of the phase. a channel between 100 Hz and 160Hz and between 315 Hz and 400 Hz. The residual distortion is apparent on both sides at 31 Hz, ie a total of 62 ° compared to the total of 96 ° obtained with the old method, which represents a decrease of 35 % of total distortions.
• This improvement is due to the treatments that are applied to the frequencies where the distortions are not of the same sign the symmetrization being a particular case.
• This process may be the subject of an electro-acoustic device for equipping motor vehicles.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Stereophonic System (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=55361535

Family Applications (1)

Country Status (5)

Family Cites Families (7)

• 2015
  • 2015-10-20 FR FR1502209A patent/FR3042673B1/fr active Active
• 2016
  • 2016-10-17 JP JP2018520615A patent/JP2018535597A/ja active Pending
  • 2016-10-17 US US15/768,982 patent/US20190069113A1/en not_active Abandoned
  • 2016-10-17 EP EP16809897.8A patent/EP3366048A1/de not_active Withdrawn
  • 2016-10-17 WO PCT/FR2016/000169 patent/WO2017068249A1/fr active Application Filing

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