Method for processing a signal from an acoustic emission system of a vehicle and vehicle comprising this acoustic emission system

An acoustic emission system for a vehicle, comprising:

• an electroacoustic transducer comprising a support and a sound exciter fixed on said support, said sound exciter being suitable for causing the support to vibrate in order to generate audio sounds, the support comprising at least one element among an interior door trim panel, a dashboard and a side pillar, said electroacoustic transducer having a resonant frequency which is intrinsic,
• an electrical signal generator connected to the electroacoustic transducer, the generator being suitable for transmitting a calibration signal to the electroacoustic transducer, the calibration signal having a frequency which varies within a predefined frequency band,
• a load having a predetermined impedance, connected between the generator and the electroacoustic transducer,
• a first voltage measuring device suitable for measuring the voltage (V1) across the terminals of the load during emission of the sound corresponding to the calibration signal as a function of the frequency of the calibration signal,
• a second voltage measuring device suitable for measuring the voltage (V2) across the terminals of the assembly of said load and of said electroacoustic transducer during emission of the sound corresponding to the calibration signal as a function of the frequency of the calibration signal,
• a database containing acoustic filters, said acoustic filters being corrected in amplitude and/or in phase as a function of each resonant frequency, each acoustic filter being specific to a given resonant frequency of the electroacoustic transducer,
• a computer suitable for determining the resonant frequency of the electroacoustic transducer from the calibration signal and from the voltages measured respectively by said first measuring device and said second measuring device, based on the variation in voltage across the terminals of the load and on the variation in voltage of the assembly of the load and the electroacoustic transducer, and from the formula below:
• Rt(f)=(V2(f)−V1(f))/(V1(f)/R0),
• R0 being the impedance of the load, said computer being suitable for choosing a set of acoustic filters from the database as a function of the determined resonant frequency.

A method for processing an electrical signal for an acoustic emission system, of a vehicle, the acoustic system comprising a generator having an input suitable for receiving an electrical signal to be played, at least one electroacoustic transducer connected to the generator, a load having a predetermined impedance, a first measuring device, a second measuring device, a database containing sets of acoustic filters, a computer connected to the generator and to the database, said electroacoustic transducer comprising a support and a sound exciter fixed on said support and suitable for causing it to vibrate in order to generate audio sounds, the support comprising at least one element among an interior door trim panel, a dashboard and a side pillar, said electroacoustic transducer having a resonant frequency which is intrinsic, each set of acoustic filters having been established, during a preliminary step, for a resonant frequency of the electroacoustic transducer, the method comprising carrying out the following steps for each electroacoustic transducer:

• a0) a preliminary step of establishing the acoustic filters as a function of the resonant frequency of the electroacoustic transducer, said preliminary step being carried out by empirical measurements;
• a1) transmitting a calibration signal to the electroacoustic transducer, said calibration signal having a frequency which varies within a band of predefined frequencies,
• b) emitting a sound based on the calibration signal, by the electroacoustic transducer;
• c1) measuring the voltage across the terminals of the load during the emission of sound by the electroacoustic transducer,
• c2) measuring the variation of the voltage (V1) across the terminals of the load during the emission of the sound corresponding to the calibration signal by the first measuring device,
• c3) measuring the variation in voltage (V2) across the terminals of the assembly of the load and the electroacoustic transducer during emission of the sound corresponding to the calibration signal by the second measuring device,
• d) calculating the variation in impedances of the electroacoustic transducer as a function of the variation in frequencies of the calibration signal based on the variation in voltage across the terminals of the load and on the variation in voltage of the assembly of the load and electroacoustic transducer, and from the formula below:
• Rt(f)=(V2(f)−V1(f))/(V1(f)/R0),
• R0 being the impedance of the load,
• e) determining the resonant frequency of the electroacoustic transducer from the variation in calculated impedances, the resonant frequency corresponding to the frequency of the calibration signal for which the maximum value of the calculated impedances is determined;
• f) selecting a set of acoustic filters in the database based on the determined resonant frequency, said set of acoustic filters comprising amplitudes corrected and/or phases corrected as a function of the resonant frequency,
• g) applying said set of acoustic filters to the electrical signal in order to process said electrical signal coming from the input prior to its transmission to said electroacoustic transducer.