Comparison of Full Modulation and Formant-Modulation Methods of Speech Intelligibility Measurement

In this paper, comparing of the full modulation and full formant-modulation methods of speech intelligibility measurement according to the measurements accuracy under the conditions of noise interference has been made. By means of computer modeling of the measuring the speech transmission index (STI), the dependences of the STI estimates errors on the signal-to-noise ratio and on the duration of the test signals were obtained. It is shown that the accuracy of STI estimates is practically the same for both methods. In particular, it is shown that the use of test signals with a duration of 4 s when measuring STI is minimally acceptable and provides an estimation error of 0.03. The use of test signals with a duration of 8 s and 16 s allows reducing the STI estimation error to 0.02 and 0.01, respectively.