[Dependence of 'audio-phonatoric coupling' of speech rate and speech loudness]

The 'audio-phonatoric coupling' (APC) was investigated in two independent experiments. Slightly delayed auditory feedback (delay time 40 ms) of the subjects' own speech was used as experimental method. The first experiment was conducted to examine whether the strength of the APC depends on the speech rate. In this experiment 16 male Subjects (Ss) were required to utter the testword/tatatas/either with stress placing on the first or second syllable at two different speech rates (fast and slow). In 16% of the randomly chosen speech trials, the delayed auditory feedback (DAF; 40 ms delay) was introduced. It could be shown that the stressed phonation was significantly lengthened under the DAF condition. This lengthening was greater when Ss spoke slowly. The unstressed phonations were not influenced by the DAF condition. The second experiment was conducted to examine whether or not speech intensity effects APC. Nine male Ss were required to utter the testword/tatatas/either with stress placing on the first or second syllable using three different speech intensities (30 dB, 50 dB and 70 dB). In 16% of the randomly chosen speech trials DAF condition was introduced. It could be shown that speech intensity does not influence the DAF effect (lengthening of stressed phonation). These findings were taken as evidence that the auditory feedback of the subjects' own speech can be incorporated into speech control during ongoing speech. Obviously, this feedback information is efficient only during the production of stressed syllables, and varies as a function of speech rate. In addition, the significance of stressed syllables for the structuring of speech is discussed.