NOISE REDUCTION SYSTEM

Electronic circuitry as described which enhances the intelligibility of a speech signal corrupted by low-frequency noise while tending to retain frequency components of the signal characteristic of natural-sounding speech. The circuitry includes a broad band channel which passes the speech signal with little spectral distortion. A high-pass channel produces a high-pass signal corresponding to high-frequency components of the speech signal, components which in themselves provide the human ear with considerable information for discernment of different sounds. An operational amplifier in a summing configuration combines the broadband and high-pass signals to produce a processed speech signal with enhanced intelligibility. Gain control circuitry associated with the high-pass channel reduces gain in the high-pass channel with increasing intensity of high-frequency speech signal components thereby tending to enhance the speech signal to an increasing degree at low signal levels and to otherwise produce a processed speech signal suitable for reproduction of natural-sounding speech.