An analysis of articulation index theory as applied to different speech material

Abstract

We have reported earlier [J. Acoust. Soc. Am. Suppl. 1 73, S102–103 (1983)] the details of an articulation index (AI) scheme that was found satisfactory for the nonsense syllable material we use. We now explore the ways of extending the scheme to include speech material of different redundancy level and different phonemic composition. Using our own data, as well as that of early AI investigators, we examine the basic assumptions of the AI theory for various speech materials. These include the properties of additivity, band independency and monotonicity, as well as the importance function, and the intelligibility‐articulation transfer function. The validity of the resulting AI scheme is discussed in terms of the magnitude of the error in speech intelligibility predictions for various speech materials. [Work supported by NINCDS.]