19. Speech Intelligibility Measurements Using TEF Analysis

Presented at the 113th Meeting of the Acoustical Society of America, Paper T5, (May 1987).

Recent investigations into the measurement of speech intelligibility using large listener groups (three groups of 30 each) in a cathedral, a concert hall, and a classic motion picture theater of the early 1930s suggest that a listener’s subjective intelligibility score will be best matched in objective testing by dividing the sound considered to be direct sound from sound considered to be reverberant sound at the highest level return within the first 50 ms. This, in a majority of cases, results in using only the first arrival and no integration of early sound.

Evidence will be presented that indicates that the use of impulse squared measurements that fail to process the signal as a complex analytic signal often fail to properly record major reflective signals unless extensive spatial averaging is resorted to. The paper will be supported by actual postprocessing of data taken with a Techron TEF analyzer using the Heyser technique for energy time curve measurement. In such measurements, minor movements of the microphone dramatically affect the impulse and doublet responses while the same change barely affects the energy time curve measurement, thus demonstrating the need for the complex analytic signal in such analysis.

Don Davis, Don Keele, Eugene Patronis; Speech intelligibility measurements sing TEF analysis. J. Acoust. Soc. Am. 1 May 1987; 81 (S1): S45. https://doi.org/10.1121/1.2024249