On the Intelligibility of Bands of Speech in Noise

Articulation tests were conducted with a large number of communication systems having band widths ranging from about one‐half octave to a system covering the entire range of speech frequencies. The systems were linear and their responses were approximately uniform over the pass band, with sharp cut‐offs at either end. The acoustic gain of the systems was expressed relative to the transmission of speech through one meter of air between talker and listener. Two spectra of masking noise were used, and each system was tested over a wide range of speech‐to‐noise ratios. In one group of experiments the speech was filtered before mixing with noise and in the other group both the speech and the noise were passed through the same filter. For each of the band‐pass systems a relation between syllable articulation and level of received speech was obtained. From these gain functions, families of equal‐articulation contours may be derived. These contours show, for example, how the gain must be changed for a given chang...