Abstract
Voice onset time (VOT) is an acoustic property of stop consonants that is commonly manipulated in studies of phonetic perception. This paper contains a thorough description of the "progressive cutback and replacement" method of VOT manipulation, and comparison with other VOT manipulation techniques. Other acoustic properties that covary with VOT-such as fundamental frequency and formant transitions-are also discussed, along with considerations for testing VOT perception and its relationship to various other measures of auditory temporal or spectral processing. An implementation of the progressive cutback and replacement method in the Praat scripting language is presented, which is suitable for modifying natural speech for perceptual experiments involving VOT and/or related covarying F0 and intensity cues. Justifications are provided for the stimulus design choices and constraints implemented in the script.
Highlights
THE ACOUSTICS OF voice onset time (VOT) AND RELATED CUESWhen creating continua of sounds that vary by perceived voicing, there are numerous factors that can be manipulated, either in a covarying way or in an isolated way
Though Praat can be limited in some respects compared to other generalpurpose programming languages, the rationale is that (1) it is freely available, removing any financial barriers that might exist for other signal processing programs, (2) Praat is already commonly used in phonetics— acoustic phonetics—and is a flexible tool for many other basic audio manipulations including speech analysis and synthesis, and (3) PRAAT provides quick and responsive visualizations of sound waveforms and spectrograms, with accessible spectral analyses and queries for sound intensity, duration, and other properties relevant for speech
It is feasible to automate the creation of speech stimuli that vary by voice onset time (VOT) using natural speech, with a PRAAT script and modest background knowledge of covarying acoustic cues such as voice pitch (F0), firstformant (F1) transition, and aspiration intensity
Summary
When creating continua of sounds that vary by perceived voicing, there are numerous factors that can be manipulated, either in a covarying way or in an isolated way. There are well established ranged for acoustic attributes that correspond to typical speech production. The exact range of values and/or their impact on perception is unclear. II A–II F, six different acoustic properties (VOT range, fundamental frequency, vowel duration, formant frequencies, aspiration intensity, and burst spectra) are discussed because they have known or potential relevance for creating VOT continua or perceiving stimuli. Each of these attributes is directly manipulable by the Praat script accompanying this paper, or can be manipulated separately by an experimenter who desires further investigation
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