Role Of Formant Transitions Research Articles

Modeling the perception of concurrent vowels: Role of formant transitions.

When two synthetic vowels are presented concurrently and monaurally, listeners identify the members of the pair more accurately if they differ in fundamental frequency (F0), or if one of them is preceded or followed by formant transitions that specify a glide or liquid consonant. However, formant transitions do not help listeners identify the vowel to which they are linked; instead, they make the competing vowel easier to identify. One explanation is that the formant transition region provides a brief time interval during which the competing vowel is perceptually more prominent. This interpretation is supported by the predictions of two computational models of the identification of concurrent vowels that (i) perform a frequency analysis using a bank of bandpass filters, (ii) analyze the waveform in each channel using a brief, sliding temporal window, and (iii) determine which region of the signal provides the strongest evidence of each vowel. Model A [Culling and Darwin, J. Acoust. Soc. Am. 95, 1559-1569 (1994)] computes the rms energy in each channel at successive time intervals to generate running excitation patterns that serve as input to a vowel classifier, implemented as a linear associative neural network. Model B uses a temporal analysis in each channel to generate running autocorrelation functions, and it includes a further stage of source segregation [Meddis and Hewitt, J. Acoust. Soc. Am. 91, 233-245 (1992)] to partition the channels into two groups, one group providing evidence of the periodicity of the vowel with the dominant F0, the other group providing evidence of the competing vowel. Both models predicted effects of F0 and formant transitions on identification, but model B provided more accurate predictions of the pattern of listeners' identification responses. Taken together, the empirical and modeling results support the idea that the identification of concurrent vowels involves an analysis of the composite waveform using a sliding temporal window, combined with a form of F0-guided source segregation.

The role of formant transitions in the identification of Spanish fricatives

The role played by formant transitions in the identification of Argentine Spanish voiceless fricatives: [f, s, ∫] was evaluated by cross‐splicing technique of natural syllables. The test tape consisted of a set of CV syllables which were formed by the recombination of each friction portion with each vocalic portion. The vocalic portion was one of the Spanish vowels [i, a, u]. The average responses of ten listeners to these stimuli showed that the acoustic cues provided by the friction portion were sufficient for the identification of the fricative sounds. In the case of [f], the results are not in agreement with previous data obtained for English listeners [K. Harris, Lang. Speech 1(1), 1–7 (1958)], a discrepancy which may be explained by the different linguistic systems. Formant transitions seem to play some role in s/∫ distinction. But its relevant role seems to be preventing a vowel effect on the preceding fricative.

Letter: Comments on summarization of the findings of Liberman et al. regarding the role of formant transitions in the perception of voiceless stops.

In a recent paper [LaRiviere et al., J. Acoust Soc. Am. 57, 470–475 (1975)], the term ’’vocalic transition’’ was introduced with reference to an hypothesis generated by the authors. In this letter, a distinction is drawn between vocalic transition and formant transition with respect to literature citations. Subject Classification: 70.30, 70.70.

Pressure-referenced analysis of the acoustic properties of speech

Previous research by Lisker and Abramson [L. Lisker, and A. S. Abramson, “Cross Language Study of Voicing in Initial Stops: Acoustical Measurements,” Word 20, 384–422 (1964)] report measurements designated voice onset time (VOT). VOT has been shown to be reliable in distinguishing consonant cognates and also differences across languages. More recently, Stevens and Klatt [K. N. Stevens and D.H. Klatt, “Role of Formant Transitions in the Voiced-Voiceless Distinction for Stops,” J. Acoust. Soc. Am. 55, 653–659 (1974)] have noted that the voice bar and the formant transitions are traded off as the distinguishing acoustic feature in the perception of the step consonants. A new method allows for VOT equivalency measurements and a new measure designated as voice termination time. The technique simultaneously records intraoral air pressure and spectrographic speech analysis through a sonagraph. The time from peak pressure to formant onset or from formant offset to peak pressure yields measures of VOT and VTT, respectively. Air pressure can be more reliably recorded than voice bar or aspirant spike, especially for VTT measures. Comparative procedures and data are discussed for acoustic perception of “b” and “p” phonemes.

Role of formant transitions in the voiced-voiceless distinction for stops.

Previous research on acoustic cues responsible for the voiced-voiceless distinction in prestressed English plosives has emphasized the importance of voicing onset time with respect to plosive release (VOT). Voiced plosives in English normally have a short VOT (less than 20–30 msec) and a significant formant transition is present following voice onset. Voiceless plosives in prestressed position, on the other hand, have relatively long VOT's (greater than about 50 msec) and the formant transitions are essentially completed prior to voice onset. Our experiments with synthetic speech compare the role of VOT and the presence or absence of a significant formant transition following voicing onset as cues for the voiced-voiceless distinction. The data indicate that there is a significant trading relationship between these two cues. The presence or absence of a rapid spectral change following voice onset produces up to 15-msec change in the location of the perceived phoneme boundary as measured in terms of absolute VOT. One can speculate that the auditory system may be predisposed to detect the presence or absence of a rapid spectrum change as a general property of acoustic inputs. If this is the case, then the acquisition of the voiced-voiceless distinction in infants may be conditioned initially by the presence or absence of this property at the onset of voicing rather than by absolute VOT.

On the Role of Formant Transitions in Vowel Recognition

On the Role of Formant Transitions in Vowel Recognition

Second- and Third-Formant Loci in English Fricative Consonants

The role of formant transitions in the perception of consonants can be studied, using synthetic speech generated from hand-painted spectrograms, either (1) by holding the formants at fixed frequencies and varying the transitions through a broad range or (2) by varying the frequencies of straight (zero transition) formants. Results obtained by the former method for the voiced fricatives of English were presented at the 1960 Fall Meeting of this Society. In the present study, the latter technique is applied (for second and third formants) to the comparison of /v/ and /ð/ without added friction, and to the comparison of /z/ and /ȝ/ with “neutral” friction. On the assumption that second- and third-formant loci are essentially the same for the corresponding voiced and voiceless fricatives, the results to be reported furnish information on transition cues for all eight fricative consonants of English.