Falling F0 Contour Research Articles

The Brain’s Response to the Human Voice Depends on the Incidence of Autistic Traits in the General Population

Optimal brain sensitivity to the fundamental frequency (F0) contour changes in the human voice is important for understanding a speaker’s intonation, and consequently, the speaker’s attitude. However, whether sensitivity in the brain’s response to a human voice F0 contour change varies with an interaction between an individual’s traits (i.e., autistic traits) and a human voice element (i.e., presence or absence of communicative action such as calling) has not been investigated. In the present study, we investigated the neural processes involved in the perception of F0 contour changes in the Japanese monosyllables “ne” and “nu.” “Ne” is an interjection that means “hi” or “hey” in English; pronunciation of “ne” with a high falling F0 contour is used when the speaker wants to attract a listener’s attention (i.e., social intonation). Meanwhile, the Japanese concrete noun “nu” has no communicative meaning. We applied an adaptive spatial filtering method to the neuromagnetic time course recorded by whole-head magnetoencephalography (MEG) and estimated the spatiotemporal frequency dynamics of event-related cerebral oscillatory changes in beta band during the oddball paradigm. During the perception of the F0 contour change when “ne” was presented, there was event-related de-synchronization (ERD) in the right temporal lobe. In contrast, during the perception of the F0 contour change when “nu” was presented, ERD occurred in the left temporal lobe and in the bilateral occipital lobes. ERD that occurred during the social stimulus “ne” in the right hemisphere was significantly correlated with a greater number of autistic traits measured according to the Autism Spectrum Quotient (AQ), suggesting that the differences in human voice processing are associated with higher autistic traits, even in non-clinical subjects.

Spatiotemporal frequency characteristics of cerebral oscillations during the perception of fundamental frequency contour changes in one-syllable intonation

Accurate perception of fundamental frequency (F0) contour changes in the human voice is important for understanding a speaker's intonation, and consequently also his/her attitude. In this study, we investigated the neural processes involved in the perception of F0 contour changes in the Japanese one-syllable interjection “ne” in 21 native-Japanese listeners. A passive oddball paradigm was applied in which “ne” with a high falling F0 contour, used when urging a reaction from the listener, was randomly presented as a rare deviant among a frequent “ne” syllable with a flat F0 contour (i.e., meaningless intonation). We applied an adaptive spatial filtering method to the neuromagnetic time course recorded by whole-head magnetoencephalography (MEG) and estimated the spatiotemporal frequency dynamics of event-related cerebral oscillatory changes in the oddball paradigm. Our results demonstrated a significant elevation of beta band event-related desynchronization (ERD) in the right temporal and frontal areas, in time windows from 100 to 300 and from 300 to 500ms after the onset of deviant stimuli (high falling F0 contour). This is the first study to reveal detailed spatiotemporal frequency characteristics of cerebral oscillations during the perception of intonational (not lexical) F0 contour changes in the human voice. The results further confirmed that the right hemisphere is associated with perception of intonational F0 contour information in the human voice, especially in early time windows.

The Perception of Prominence Patterns

The term ‘stress’ is used to refer to the perceptual salience at certain places in strings of syllables, but it has several different referents: (a) relative syllable salience in an utterance; this is syllable-, not word-oriented; (b) stress in a word; this is part of the lexical phonology; (c) stressing of words in utterances for various aspects of propositional and expressive meaning, often called ‘accent(uation)’. Referents b and c are word- and meaning-oriented. In this article, the terms are more stringently defined. ‘Stress’ is only used to refer to a lexical stress position (referent b), i.e. a syllable in a word that becomes the docking place for various types of ‘accent’ to weight words in utterances (referent c). ‘Stress’ has no physical attributes by itself. ‘Prominence’ refers to the patterns of salience in syllable strings (referent a). The article reports results of an experiment in prominence perception of the logatome baba, in which the physical parameters F0, syllabic duration, and overall acoustic energy were systematically varied across the bisyllable. Sixteen German subjects had to indicate, by pressing buttons of a computerized reaction time device, whether the first or the second syllable was more prominent. F0 was a more powerful cue than the other two. Equal syllable duration on a monotone resulted in more first-syllable judgements, which could be counteracted by a slightly falling F0 contour on the second syllable to reach equal response frequencies for the two syllables. This ties in with Lehiste’s earlier findings that F0 movement increases the perception of duration. Extrapolating from the results, a research programme for prominence perception is developed that will eventually shed new light on the investigation into the nature and manifestation of speech rhythm.

Development of prosodic patterns in Mandarin-learning infants

Early prosodic development (f0 variation) was systematically measured in Mandarin-learning infants at the transition from babbling to producing first words. Spontaneous vocalizations of twenty-four infants aged 0 ; 7 to 1 ; 6 were recorded in 45-minute sessions. The speech production of twenty-four caregivers was also audio-recorded during caregiver-infant natural daily interactions at home. All recordings were transcribed using broad prosodic patterns. Analysis revealed four major findings: (1) falling f0 contours were more prominently produced than level and rising contours; (2) high prosodic patterns occurred more frequently than mid and low prosodic patterns; (3) these distribution patterns of f0 contours showed significant similarities in babbling and early words; and (4) these distribution patterns were also similar in infants' and their caregivers' data.

Modeling the categorization of a large F1–F2–F3 continuum by Finnish listeners.

A continuum of 972 vowels was synthesized, each of which was 115 ms in duration with a falling F0 contour (125–100 Hz). F1 ranged (in 0.5‐ Bark steps) from 250 to 760 Hz, F2 from 750 to 2260 Hz and F3 from 1360 to 3080 Hz. F4 and F5 were fixed at 3500 and 4500 Hz, respectively. (Constraints were placed on formant separations to ensure relatively natural stimuli.) This continuum was previously categorized by a group of English speakers [T. M. Nearey and M. Kiefte, J. Acoust. Soc. Am. 96, 3284(A) (1994)]. The same stimuli were presented to 14 speakers of Finnish at the University of Turku. Subjects categorized these stimuli with labels for the nine Finnish vowels, / i, e, y, ö, æ, u, o/. Results of logistic regression analysis will be presented and compared with previous findings for English. [Work supported by SSHRC. The assistance of Ulla Fisher and Dr. Olli Aaltonen of the University of Turku in collecting the Finnish data is gratefully acknowledged.]

Modeling listeners’ categorization of a large F1-F2-F3 continuum

A number of alternate spectral representations have been suggested for vowel spectra [see H. Hermansky, J. Acoust. Soc. Am. 87, 1738–1752 (1990)]. To better evaluate the perceptual relevance of some of these, 972 vowels were synthesized. The stimuli were each 115 ms in duration with a falling F0 contour (125–100 Hz). F1 ranged (in 0.5 Bark steps) from 250 to 760, F2 from 750 to 2260, and F3 from 1360 to 3080 Hz. F4 and F5 were fixed at 3500 and 4500 Hz, respectively. (Constraints were placed on formant separations to ensure relatively natural stimuli.) Fifteen speakers of Western Canadian English categorized the stimuli as the vowels /i, i, e, eh, æ, inverted vee, inverted open aye, o, u, u, hooked backward eh/. Preliminary results indicate that while nominal synthesis formant frequencies can provide a relatively good fit to the data, alternate representations such as cepstral coefficients based on Hermansky’s PLP analysis may provide moderate improvements of fit. However, linear transformations of the PLP cepstra show strong correlations with formant frequencies [similar to those noted by D. Broad and F. Clermont, J. Acoust. Soc. Am. 86, 2013–2017 (1985)]. [Work supported by SSHRC.]

Beginnings of Prosodic Organization: Intonation and Duration Patterns of Disyllables Produced by Japanese and French Infants

In this study, some prosodic aspects of the disyllabic vocalizations (both babbling and words) produced by four French and four Japanese children of about 18 months of age, are examined. F0 contour and vowel durations in disyllables are found to be clearly language-specific. For French infants, rising F0 contours and final syllable lengthening are the rule, whereas falling F0 contours and absence of final lengthening are the rule for Japanese children. These results are congruent with adult prosody in the two languages. They hold for both babbling and utterances identified as words. The disyllables produced by the Japanese infants reflect adult forms not only in terms of global intonation patterns, but also in terms of tone and duration characteristics at the lexical level.

The perception of the low‐high (LH) tonal sequence

It has been reported that the primary cue for the HL tonal perception in Japanese is not the actual F0 peak location but rather a falling F0 contour. The F0 fall may be significantly delayed, resulting in the F0 peak within the L‐toned syllable. Furthermore, it was found earlier that (1) the later the F0 fall in the L‐toned syllable, the steeper the fall rate required and (2) the fall must begin within the first two‐thirds of the duration of the vowel in the L‐toned syllable. The present experiment investigates whether a lack of synchronization between F0 change and syllable boundary can be found in the perception of the LH as well. Synthesized nonsense words/mamama/were prepared in such a way that both the onset of F0 rise and the F0 peak occur at various locations, while maintaining the overall F0 contour (level‐rise‐peak‐slight fall). The stimuli were presented to native speakers of Japanese to determine the boundary between the categorical perception of LHH and LLH. The results show that the LH sequence is more constrained than the HL in terms of temporal alignment of F0 change and the syllable boundary.

Delayed pitch fall in Japanese

The Tokyo dialect of Japanese is regarded as a prototypical pitch accent language where the location of F0 fall is the only acoustic correlate of the accent. Neustupný [Onsei‐gakkai Kaihoo 121 (1966)], however, reported that F0 fall does not always synchronize with an accented mora but may be carried over to the following mora. Sugito [Shooin Joshi Daigaku Ronshuu 10 (1972)] found that native speakers perceived a pitch accent on a mora when it was followed by a falling F0 contour and also that the F0 peak value in the accented mora need not be higher than that in the following mora. Not well investigated though is the correlation between the peak location and the steepness of falling contour. The working hypothesis is that the later the F0 fall occurs, the faster F0 drops. This delayed pitch fall is characterized in terms of (1) the F0 peak location and (2) the steepness of F0 contour computed in Hz/cs. The results from 560 tokens uttered by seven speakers of the Tokyo dialect confirmed our hypothesis. [Work partially supported by Sloan grant to Berkeley Cognitive Science Program.]

Control of speech prosody in Broca's aphasia

A typical clinical description of the speech of Broca's aphasics includes the characteristics of nonfluency, agrammatism, and dysprosody. This study aims to objectively evaluate the subjective impression of dysprosody using computerized techniques to measure fundamental frequency (F0) and segmental timing. We examined three rudimentary aspects of normal speech production: (1) terminal falling F0 contour in utterance-final position, (2) declination of F0 peaks throughout the course of an utterance, and (3) segmental lengthening in utterance-final position. Seventy-five two-word utterances, extracted from the spontaneous speech of three Broca's aphasics, were found to exhibit both terminal falling F0 contours and declination despite interword pauses of up to 3.5 s. However, the timing of these utterances showed no utterance-final lengthening. These results are discussed in terms of the speech planning capabilities of these patients and the apparent dissociation between programming of F0 and timing. A controlled experiment was conducted in order to rule out the possibility that a phonetic influence masked utterance-final lengthening in the spontaneous speech sample; the results confirmed the previous observations for both segmental timing and F0. [Supported by NIH Grants NS 11408, NS 13028, and the MIT Research Laboratory of Electronics.]