Patent ID: 6944284
Filing Date: 2005-09-13
Classification: B06B

Abstract:
1. A method of controlling the sound volume produced by an audio transducer, the method comprising the steps of: generating a first signal that is in the audible frequency range; generating a second signal where the second signal is a digital pulse train signal with a mark-space ratio of less than 100%, where the frequency of the second signal is higher than the frequency of the first signal; modulating the amplitude of the first signal with the digital pulse train signal to generate an output signal with similar timbre to that of the first signal; and applying the output signal to the audio transducer; whereby the volume of sound produced by the audio transducer varies with the mark-space ratio of the digital pulse train signal, wherein the frequency of the second signal is determined by a first clock frequency, and the mark space ratio of the second signal is a multiple of a ratio of the first clock frequency to a second clock frequency that is higher than the first clock frequency.