Speech Signal Characteristics
Speech has some characteristics that are very different then the
feedback signal. It has a more complex, more natural waveform in the time
domain. Its amplitude varies much more and its frequency changes much
faster than feedback.
The Spectrogram shows that the majority of the signal is in the lower
frequencies, but the s-type consonants can have power up into the 10kHz range.
Click here to listen to sample of Speech
The frequency domain representation yields much of the same
information. It shows the power more spread out amongst the frequencies.
The most important of these characteristics is that the speech signal has
far less power at any given frequency than the feedback signal. Because
of this property of the two signals we can set a relative power threshold.
Any time a signals power in the frequency domain exceeds the threshold we
treat is as Feedback and band reject it at the frequencies with high power.
Feedback
Feedback Suppression
