Abstract: An audio tremolo producing system uses a rotating horn as a tremolo producing device for mid and high frequency audio signals, and an electronic tremolo producing device capable of both phase and amplitude modulation for low frequency signals.

Abstract: An apparatus for automated testing of vibrotactile responses of a patient is disclosed. The embodiment of the invention comprises a component to apply indentations and vibrations to the patient's skin to test the patient's response to vibrotactile stimuli. In the preferred embodiment of the invention, a general purpose computer functions to control the operation of the system and to record and store the patient's responses. Indentations and vibrations are produced by off-axis rotational movement of a stimulation probe. A frequency modulated signal generated by the computer is used to control the motor which drives the stimulation probe. The embodiment of the present invention is able to reliably repeat each test so that the tests are reproducible and are carried out in an objective manner.