Adaptive equalizer for variable length sound tubes utilizing an acoustical time of flight measurement

摘要

In a device having a sound tube and a receiver, a test signal is generated to apply to the receiver. An outgoing acoustic wave is created at the receiver from the test signal. A reflected acoustic wave is received at the receiver, wherein the reflected acoustic wave is delayed in time from the outgoing acoustic wave. A difference in time is measured between the outgoing acoustic wave and the reflected acoustic wave. The difference in time is used to estimate a length of the sound tube.