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There are indications in the literature on speech perception that differences in rise and decay times of the amplitude envelope are relevant physical correlates in phonemic contrasts. Yet, little is known about the perception of rise and decay times as such. In the present study we have attempted to establish JND's for both rise and decay times of 1000-Hz sine waves as well as white noise bursts by means of an adjustment method. The rise and decay of stimulus amplitude were synthesized to be linear functions of time. Results show that the JND for a change in rise/decay time is generally about 25% of the duration of the rise/decay time. This Weber fraction is a minimum at rise/decay times of about 80 ms and increases significantly for rise/decay times below 20 ms. Of the four signal conditions (rise versus decay, sine wave versus noise), discriminations of decay time in noise bursts were performed with the greatest accuracy (at moderate rise/decay times), while changes in onset time of sine waves were discriminated best at very short rise times (where energy splatter may have contributed an additional cue). [ABSTRACT FROM AUTHOR]

In this study, the claim that intensity, as an acoustic operationalization of loudness, is a weak cue in the perception of linguistic stress is reconsidered. This claim is based on perception experiments in which loudness was varied in a naive way: All parts of the spectrum were amplified uniformly, i.e., loudness was implemented as intensity or gain. In an earlier study it was found that if a speaker produces stressed syllables in natural speech, higher frequencies increase more than lower frequencies. Varying loudness in this way would therefore be more realistic, and should bring its true cue value to the surface. Results of a perception experiment bear out that realistic intensity level manipulations (i.e., concentrated in the higher frequency bands) provide stronger stress cues than uniformly distributed intensity differences, and are close in strength to duration differences.

There is ample evidence in the literature that English and Dutch listeners tend to perceive stress on the word-initial syllable. This bias is most easily seen in the perception of (nonsense) words containing repetitions of identical syllables. In four experiments the possible causes of this bias are investigated. The results show that the bias disappears when (i) words are preceded by a spoken context, when (ii) the voice source is replaced by noise (whisper), or when (iii) the fundamental frequency level of the utterance as a whole is lowered. The data are best explained by assuming that the listener interprets the onset of voicing of an isolated word as a (silent) pitch rise from the bottom of the speaker's pitch range.

Although intensity has been reported as a reliable acoustical correlate of stress, it is generally considered a weak cue in the perception of linguistic stress. In natural speech stressed syllables are produced with more vocal effort. It is known that, if a speaker produces more vocal effort, higher frequencies increase more than lower frequencies. In this study, the effects of lexical stress on intensity are examined in the abstraction from the confounding accent variation. A production study was carried out in which ten speakers produced Dutch lexical and reiterant disyllabic minimal stress pairs spoken with and without an accent in a fixed carrier sentence. Duration, overall intensity, formant frequencies, and spectral levels in four contiguous frequency bands were measured. Results revealed that intensity differences as a function of stress are mainly located above 0.5 kHz, i.e., a change in spectral balance emphasizing higher frequencies for stressed vowels. Furthermore, we showed that the intensity differences in the higher regions are caused by an increase in physiological effort rather than by shifting formant frequencies due to stress. The potential of each acoustic correlate of stress to differentiate between initial- and final-stressed words was examined by linear discriminant analysis. Duration proved the most reliable correlate of stress. Overall intensity and vowel quality are the poorest cues. Spectral balance, however, turned out to be a reliable cue, close in strength to duration.

The goal of this experiment is to find the most important phonetic features of Dutch accent-lending pitch movements, in terms of shape, pitch level and alignment with the segmental structure. Time pressure is used as a heuristic method to isolate important phonetic aspects of pitch movements, assuming that under time pressure the speaker will preserve those aspects. In a production experiment, accent-lending rises ('1') and falls ('A') were realized under various types of time pressure. The pitch rise is time-compressed under all pressure types, which would mean that the shape of the rise is relatively unimportant. The segmental alignment of the rise proved to be more important: the onset of the rise is synchronized with the syllable onset. For the fall no fixed synchronization point was found, but its shape was relatively invariant, indicating that shape rather than exact timing is the more important feature of the fall.

Under the so-called culminative definition of stress, present-day linguists hold the view that within one word or larger domain only one syllable can bear the stress. This is in contrast with the classical (British-English) phonetic tradition which allows the occurrence of two strong stresses within certain words, which are then called 'double-stressed'. Moreover, precisely the class of double-stressed words was said to be subject to rhythmic variation (or 'stress clash'). The present paper purports to find acoustic and perceptual evidence that may allow us to choose between these competing proposals, comparing the behaviour of Dutch adjectives with canonically rising, falling, and double-stress patterns, in spoken contexts that should bear out the predicted rhythmic changes in double-stressed words. Our results argue against a strictly culminative definition of stress.