Uniform Speech-Peak Clipping in a Uniform Signal-to-Noise Spectrum Ratio

A graphical function W(r, c) has been determined experimentally, in which W is word articulation, r is the relative level of unclipped speech and the noise, and c is the amount of uniform, symmetrical, speech-peak clipping. Pre-emphasis of the speech signal gave an approximately uniform speech spectrum prior to clipping. Uniform, random noise was mixed with the clipped speech before postequalization, making the final noise spectrum similar in shape to the speech spectrum. The real-ear response of the earphones was compensated electrically to yield a uniform orthotelephonic response for the communication system, in the frequency range contributing significantly to articulation index. For constant clipping cn the function W(r, cn) approaches W(r, 0) as a limit for sufficiently large values of r. For cr+5, W≒W(r, 0). For the case of no clipping, W(r) when transformed to W(A) (A being articulation index) resembles closely the curve by Pollack.