James E. Van Hout

Method and apparatus for inducing audio vibrations

A method and apparatus of inducing vibrations and buzzes within a vehicle, e.g., from panel trim, provides a reliable and repeatable way to identify the sources of such vibrations and buzzes. According to the method, an FM transmitter modulates and transmits predetermined frequency signals to a standard FM receiver located in the interior of the car. The FM receiver receives and demodulates the signal, and then applies it to audio speakers also located within the vehicle. The output signal from the speakers induces sympathetic vibrations in vehicle components, allowing a tester to identify the sources of the vibrations and buzzes so that they may be corrected. The transmitter provides a means for a user to maintain a constant frequency or to vary the frequency within a predetermined range of frequencies. The frequency may be generated by digitally storing one complete sine wave in successive memory locations. The values can then be retrieved and converted to an analog signal. Higher frequencies are obtained by sampling at a constant rate, but skipping some of the values, thereby retrieving the sine wave at a faster rate.