Signal conditioning apparatus

摘要

An signal conditioning apparatus and method to condition a human voice signal for input to a time-domain voice recognition system. The signal conditioner normalizes sampled human voice inputs so that all inputs result in an output with substantially the same pitch and frequency bandwidth characteristics. The signal conditioner includes a pitch altering circuit that alters the pitch of the input human voice signal and a frequency band limiting circuit that limits the range of spectral information contained in a signal. The pitch altering circuit converts the input into a digital signal at a first conversion rate and converts the digital signal back to an analog signal at a second rate which is unequal to the first rate. The frequency band limit circuit is a plurality of filters at different points in the frequency spectrum.