NOVEL METHOD OF IMPROVING THE RESTITUTION OF STEREOPHONIC MODULATIONS IN AUTOMOBILES

Abstract

New method for improving the reproduction of stereophonic modulations in cars.

According to this method, in first step the level distortion in uncorrelated isobar mode is canceled first by means of the balance adjustment, in a second stage the center of the sound image is positioned at the center of the sound scene in the isobaric correlated mode in delaying the modulation feeding the loudspeaker closest to the conductor and in a third stage by canceling the stereophonic phase distortion in the isobaric mode correlated by means of a phase equalizer.

Claims

1. A method of improving the reproduction of a stereophonic modulation at a. point of listening of an automobile, characterized in that the ratio of the levels of the left and right channels is first adjusted so that the listener perceives In uncorrelated isobaric mode the two ends of the sound image with the same intensity, that in a second step a delay is applied to the signal feeding the loudspeaker closest to the listener so that the listener perceives in isobaric correlated mode the center of the sound image in the desired position and in a third step canceling the phase distortion for the listening position.

2. A stereophonic reproduction device equipped with signal processing means and characterized in that the processing means are configured to allow the implementation of the adjustment method described in claim 1.

3. A motor vehicle equipped with a device according to claim 2.

4. A software for processing stereophonic modulations, characterized in that it is capable, in a single operation, of modifying a stereophonic modulation in accordance with the method according to claim 1 and in that it is arranged to fetch on a server the the vehicle's tuning parameters according to the model and type of audio equipment.

5. A music server equipped with software according to claim 4 and further comprising in memory the correction parameters for each vehicle model and arranged to provide pieces of music corrected according to the vehicle model indicated by the customer.

Description

[0039] The curve in FIG. 1 is the original phase distortion at the left listening point [φ.sub.G-φ.sub.D].sub.G in our test vehicle.

[0040] This curve is absolutely catastrophic, it reflects the quality of reproduction of uncorrected original installations.

[0041] The curve of FIG. 2 is the residual phase distortion in this same vehicle after application of a delay of 1.31 ms on the left channel. There is some improvement but the residual phase distortion is still very important.

[0042] The curve of FIG. 3 is the residual phase distortion after application of the phase distortion cancellation procedure.

[0043] This result is quite remarkable. It shows that the acoustic phase is a linear function of the electrical phase, which was not obvious. Given the complexity of sound. reproduction in a confined space of small dimensions we could have had ruptures of linearity.

[0044] For industrial applications, the present invention can take several forms.

[0045] For applications in vehicles, for original equipments or aftermarket, it will be necessary for those skilled in the art to implement in the car stereo reproduction system a real-time software capable of modifying the stereophonic modulation in accordance with the method according to the present invention After the introduction of the vehicle specific parameters.

[0046] Since the method according to the present invention is pure signal processing without modification of the installation in the car, the desired result can be obtained with a conventional installation by modifying the audio file.

[0047] In Cool Edit Pro the modification of the audio file according to the present invention is done in 3 steps.

[0048] It would be advantageous to create a software allowing the modification in a single step which could be enhanced by a level equalization, which would make it possible to obtain a quality of reproduction capable of satisfying the most demanding amateurs who could thus obtaining versions of their preferred discs adapted to their vehicle.

[0049] This software would look for the setting of the modification on a server indicating the model of the vehicle and its audio equipment.

[0050] A variant would be that an online music sales site like ITUNE enriches its offer by proposing corrected versions adapted to each vehicle.