Overview

The goal of this chapter is to systematically consider quality measurements for segmental intelligibility. In the previous chapters, numerous components of speech quality and projections of measurement procedures were presented, discussed and systematized. This chapter follows with an in-depth look at the example of segmental intelligibility as one dimension. It shows that - in the mathematical sense - this dimension is in turn a function of several variables, for which speech quality assessment today still has no solvent equation. One reason for this is that certain linguistic questions that determine the results of these measurements still have not been answered and in part have yet to be posed.

The dimension to be discussed in the following is speech comprehensibility and intelligibility. Speech intelligibility is the dominant dimension of speech quality. When speech sounds are not intelligible, communication cannot be successfully accomplished. The expectations of the listener are not fulfilled. No quality is assigned to the speech signal.

Measuring speech intelligibility proves to be a multifaceted task. The leitmotif of this chapter is determining exactly individual quality elements of speech sounds; additional emphasis is placed on the measuring object. Speech intelligibility is restricted to segmental intelligibility - in part, as will be shown, also only to segmental comprehensibility. It is of benefit that numerous procedures to judge speech intelligibility are documented and that important experience in the use of these procedures in quite different measurement contexts is available. This is not necessarily the case for other dimensions of speech quality...