Duration Of Silent Interval Research Articles

Learning to pause: Fidelity of and biases in the developmental acquisition of gaps in the communicative signals of a songbird.

The temporal organization of sounds used in social contexts can provide information about signal function and evoke varying responses in listeners (receivers). For example, music is a universal and learned human behavior that is characterized by different rhythms and tempos that can evoke disparate responses in listeners. Similarly, birdsong is a social behavior in songbirds that is learned during critical periods in development and used to evoke physiological and behavioral responses in receivers. Recent investigations have begun to reveal the breadth of universal patterns in birdsong and their similarities to common patterns in speech and music, but relatively little is known about the degree to which biological predispositions and developmental experiences interact to shape the temporal patterning of birdsong. Here, we investigated how biological predispositions modulate the acquisition and production of an important temporal feature of birdsong, namely the duration of silent pauses ("gaps") between vocal elements ("syllables"). Through analyses of semi-naturally raised and experimentally tutored zebra finches, we observed that juvenile zebra finches imitate the durations of the silent gaps in their tutor's song. Further, when juveniles were experimentally tutored with stimuli containing a wide range of gap durations, we observed biases in the prevalence and stereotypy of gap durations. Together, these studies demonstrate how biological predispositions and developmental experiences differently affect distinct temporal features of birdsong and highlight similarities in developmental plasticity across birdsong, speech, and music. RESEARCH HIGHLIGHTS: The temporal organization of learned acoustic patterns can be similar across human cultures and across species, suggesting biological predispositions in acquisition. We studied how biological predispositions and developmental experiences affect an important temporal feature of birdsong, namely the duration of silent intervals between vocal elements ("gaps"). Semi-naturally and experimentally tutored zebra finches imitated the durations of gaps in their tutor's song and displayed some biases in the learning and production of gap durations and ingap variability. These findings in the zebra finch provide parallels with the acquisition of temporal features of speech and music in humans.

Effects of silent interstimulus interval duration between precursor and target stimuli on spectral context effects in vowel and consonant categorization

Effects of silent interstimulus interval duration between precursor and target stimuli on spectral context effects in vowel and consonant categorization

Effect of Clear Speech on the Duration of Silent Intervals at Syntactic and Phonemic Boundaries in the Speech of Individuals With Parkinson Disease.

Purpose The purpose of the current investigation was to determine the extent to which individuals with and without Parkinson disease (PD) modified silent interval durations when using a clear speaking style. Method Ten individuals with idiopathic PD and 10 older adult control speakers produced a reading passage using both habitual and clear speaking styles. Silent intervals lasting 15 ms and longer were identified and extracted. Each silent interval was categorized according to the surrounding syntactic context of the reading passage. In addition, voiceless stop gaps that occurred within words, phrases, or clauses were categorized by the preceding phonemic context. Results Statistical analyses revealed that all participants increased silent interval duration with a clear speaking style at inter-sentence and intra-sentence syntactic boundaries. Compared to controls, individuals with PD exhibited significantly less increase in silent interval durations at these syntactic boundaries. Control speakers also increased silent stop gap durations in the clear speaking style regardless of preceding phonemic context. Individuals with PD, however, only increased stop gap duration when the silent interval was preceded by a sonorant. Conclusion These findings suggest that speakers with PD exhibit less clarity-related increase in silent interval duration than control speakers. In addition, speakers with PD exhibited significant increases in silent interval duration that coincided with syntactic boundaries of the reading passage but little to no clarity-related modulation of stop gap intervals. Therefore, these data suggest that speakers with PD exhibited changes in silent interval durations that were more so associated with modulation of speech prosody than articulation when using a clearer speaking style.

A new species of nurse-frog (Aromobatidae, Allobates) from the Juami River basin, northwestern Brazilian Amazonia.

We describe a new species of nurse-frog (Aromobatidae, Allobates) from northwestern Brazilian Amazon. Allobates juami sp. nov. is distinguished from similar congeneric species by the combination of the following characters: body-size range (snout-to-vent length 17.5-18.5 mm), lack of dark pigments on ventral surfaces of male specimens, dorsal color pattern (predominantly solid dark brown, but conspicuously light brown over snout and urostyle regions), presence of conspicuous pale dorsolateral and ventrolateral stripes, and presence of a diffuse pale paracloacal mark. The advertisement call of the new species lasts 2.5-5.1 s, contains 60-73 short notes (trills), and is emitted at an average rate of 13 notes per second within trills. Duration of silent intervals between notes ranges between 0.020-0.050 s, and the peak frequency of notes ranges from 4.59 to 5.47 kHz. The new species is currently known only from the type locality at Estação Ecológica Juami-Japurá (1.96455° S, 67.93579° W; ~ 87 m a.s.l.).

Relationship between auditory degradation and fricatives/affricates production and perception in elderly listeners

Elderly people often complain that they struggle with consonant identification when listening to spoken language. In previous studies, we conducted several experiments, including identification tests for young and elderly listeners using /shi/-/chi/ (CV) and /ishi/-/ichi/ (VCV) continua. We also recorded production of such CV and VCV syllables. For the CV stimuli, confusion of /shi/ as /chi/ increased when the frication had a long rise time. The degree of confusion increased when auditory property degradation was observed such as threshold elevation in high frequency. In the VCV stimuli, confusion of /ichi/ as /ishi/ occurred for a long silent interval between the first V and C with auditory property degradation. In the present study, we analyzed the utterances of those CV and VCV syllables and measured the duration of frication and silent interval. The direction of the boundary shift in the perception of fricatives and affricates by auditory degradation was consistent with that of production. We found that degradation of auditory properties affects both perception and production of fricatives and affricates in elderly people.

Variability in the temporal parameters in the song of the Bengalese finch (Lonchura striata var. domestica).

Birdsong provides a unique model for studying the control mechanisms of complex sequential behaviors. The present study aimed to demonstrate that multiple factors affect temporal control in the song production. We analyzed the song of Bengalese finches in various time ranges to address factors that affected the duration of acoustic elements (notes) and silent intervals (gaps). The gaps showed more jitter across song renditions than did notes. Gaps had longer duration in branching points of song sequence than in stereotypic transitions, and the duration of a gap was correlated with the duration of the note that preceded the gap. When looking at the variation among song renditions, we found notable factors in three time ranges: within-day drift, within-bout changes, and local jitter. Note durations shortened over time from morning to evening. Within each song bout note durations lengthened as singing progressed, while gap durations lengthened only during the late part of song bout. Further analysis after removing these drift factors confirmed that the jitter remained in local song sequences. These results suggest distinct sources of temporal variability exist at multiple levels on the basis of this note-gap relationship, and that song comprised a mixture of these sources.

The role of temporal cues in word identification by younger and older adults: Effects of sentence context

Prior investigations, using isolated words as stimuli, have shown that older listeners tend to require longer temporal cues than younger listeners to switch their percept from one word to its phonetically contrasting counterpart. The extent to which this age effect occurs in sentence contexts is investigated in the present study. The hypothesis was that perception of temporal cues differs for words presented in isolation and a sentence context and that this effect may vary between younger and older listeners. Younger and older listeners with normal-hearing and older listeners with hearing loss identified phonetically contrasting word pairs in natural speech continua that varied by a single temporal cue: voice-onset time, vowel duration, transition duration, and silent interval duration. The words were presented in isolation and in sentences. A context effect was shown for most continua, in which listeners required longer temporal cues in sentences than in isolated words. Additionally, older listeners required longer cues at the crossover points than younger listeners for most but not all continua. In general, the findings support the conclusion that older listeners tend to require longer target temporal cues than younger normal-hearing listeners in identifying phonetically contrasting word pairs in isolation and sentence contexts.

Do Acoustic Parameters of Begging Calls of Cory’s Shearwaters Calonectris diomedea Reflect Chick Body Condition?

A previous study of begging in Cory’s Shearwaters (Calonectris diomedea) found that chicks convey information about their body condition through the number and rate of begging calls uttered during a feeding session. Parents delivered larger meals when chicks begged more intensely. Here we test whether acoustic properties of begging calls of Cory’s Shearwaters are related to body condition of chicks, and whether parents are responsive to changes in acoustic parameters. Acoustic parameters, which were analyzed using semi-automatic call contour analysis, included the duration of calls and silent intervals, the minimum, mean and maximum frequency in a call and the number of frequency peaks within a call. We found that, in contrast to the number and rate of begging calls, acoustic parameters did not reflect chick body condition, and were not correlated with the meal size delivered by the attending adults.

The role of silent intervals for sentence intelligibility in fluctuating noise in hearing-impaired listeners

Fluctuating interfering noises are highly suitable for speech audiometry because of the large inter-individual variability in intelligibility results. This study explores the maximum duration of silent intervals in the masker as an important factor underlying sentence intelligibility in fluctuating noise. Three versions of speech-simulating fluctuating interfering noises based on the icra noises (Dreschler et al, ) were explored: The original noise which simulates one interfering speaker and contains pause durations up to two seconds, as well as two modified versions with pause durations limited to 250 ms and 62.5 ms, respectively. In addition, a stationary speech-shaped noise was used. Test-retest reliability as well as speech reception threshold (SRT) and speech intelligibility function slope were determined with hearing-impaired subjects. All fluctuating noises differentiated very well between subjects. Partial rank correlation analysis showed that SRTs in fluctuating noise with longest maximum pause durations mostly depended on SRTs in quiet. SRTs in fluctuating noises with smaller maximum pause durations correlated both with SRTs in quiet and in stationary noise.SumarioLos ruidos fluctuantes de interferencia son muy apropiados en logoaudiometría debido a la gran variabilidad inter-individuos en los resultados de inteligibilidad. Este estudio explora la duración máxima de intervalos de silencio en el enmascarador, como un importante factor subyacente en la inteligibilidad de frases en medio de ruido fluctuante. Se exploraron tres versiones de ruidos fluctuantes de interferencia simulando lenguaje, con base en los ruidos icra (Dreschler y col., 2001): el ruido original que simula la interferencia de un hablante y contiene pausas de hasta 2 segundos de duración, y también dos versiones modificadas con pausas de duración limitadas a 250 mseg y 62.5 mseg, respectivamente. Además, se utilizó un ruido estacionario moldeado como lenguaje. Se determinó la confiabilidad test-retest al igual que la pendiente de las funciones del SRT y la inteligibilidad del lenguaje, en sujetos hipoacúsicos. Todos los ruidos fluctuantes se diferenciaron muy bien entre los sujetos. Un análisis de correlación de rango parcial mostró que los SRT en ruido fluctuante con las duraciones más prolongadas de pausa máxima, dependían del SRT en silencio. Los SRT en ruido fluctuante con duraciones menores de pausa máxima, correlacionaron tanto con los SRT en silencio como con el ruido estacionario.

Durational, proportionate, and absolute frequency characteristic of disfluencies: a longitudinal study regarding persistence and recovery.

The main objective of this study was to investigate developmental aspects of disfluencies over time as stuttering persists or ameliorates for 2 groups of preschool age children who stutter. Results indicated that the frequency, type, and duration of disfluencies remained relatively constant instead of increasing as expected in the persistent group over a 3-year period. In contrast, the recovered group's initially higher frequency of disfluency decreased over time, as did their number of repetition units and proportion of disrhythmic phonations, while the duration of silent intervals between repetition units and proportion of monosyllabic word repetitions increased.

Time decay of auditory stream biasing.

In an experiment designed to investigate the time decay of auditory stream biasing (ASB), subjects were required to listen to a 10-sec induction sequence of repeated tones (AAAA...) designed to bias the listener's percept toward hearing an A stream. The induction sequence was followed immediately by a silent interval (0-8 sec), and then a short ABAB ... test sequence. To measure the amount of ASB remaining at the end of the silent interval, subjects were asked to indicate whether the test sequence was temporally coherent or had segregated into separate A and B streams. A plot of the mean number of segregation responses against silent-interval duration indicated that the overall time decay of ASB can be ascribed by an exponential decay function with a time constant of tau = 3.84 sec, with musicians having a longer time constant (tau = 7.84 sec) than nonmusicians (tau = 1.42 sec). The length of the time constants for musicians and nonmusicians suggests that the mechanism responsible for ASB is associated with long auditory storage and that future experiments investigating auditory streaming phenomena should use interstimulus intervals of at least 8 sec.

Temporal integration mechanisms for complex tones consisting of unresolved harmonics

There is a large effect of duration on fundamental frequency (F0) discrimination for complex tones consisting of harmonics unresolved by the peripheral auditory system [C. J. Plack and R. P. Carlyon, J. Acoust. Soc. Am. 98, 1355–1364 (1995)]. The present experiment investigated the mechanisms underlying this effect by measuring F0 discrimination for complexes of unresolved harmonics with continuous durations between 20 and 160 ms and for pairs of 20-ms unresolved complexes separated by a silent interval of between 5 and 80 ms. For the continuous signals, d′ increased by a factor of 2.4 between the 20-ms signal and the 40-ms signal. For the paired signals d′ increased relative to the 20-ms signal by a factor between 1.2 and 1.6, independent of the silent interval duration. This increase is similar to that predicted by signal detection theory. These data support the hypothesis that the pitch mechanism for unresolved harmonics can use a long integration window for continuous signals but reverts to a ‘‘multiple looks’’ mechanism, involving the efficient combination of discrete short-duration samples, when there is some discontinuity in the signal. [Work supported by MRC (UK).]

Temporal dynamics of repetitions during the early stage of childhood stuttering: an acoustic study.

The purpose of this study was to compare duration characteristics of single-syllable whole-word repetitions (with one and two repeated units) and part-word repetitions (with one repeated unit) in the speech of preschool children who stutter (N = 20) recorded near the onset of their stuttering to those of control nonstuttering children (N = 20). Disfluent episodes were identified in audiotape recordings of the subjects' conversational speech. The digitized signals were analyzed by means of the CSpeech computer software (Milenkovic, 1987). Using visual displays of sound spectrograms, the durations of the spoken repetition unit(s), the silent interval(s) between the units, and the total disfluency were measured. The stutters exhibited shorter silent intervals between spoken repetition units. The duration of the spoken repetition units was very similar for the two groups of children. The total duration of the stutterers' disfluencies was significantly shorter because of their shorter silent intervals when compared to disfluencies of equal repetition units produced by the control subjects. Statistical analysis revealed that silent interval duration was capable of differentiating stuttering from normally fluent children with 72-87% accuracy, dependent upon the disfluency type. To the degree that the groups of subjects represented random samples of the two specified populations from which they were drawn, there appears to be an overall tendency for repetitions during the early stage of stuttering to be produced at a faster rate than repetitions produced by nonstuttering children.

Verbal Memory Span in Children: Speech Timing Clues to the Mechanisms Underlying Age and Word Length Effects

According to the prevalent articulatory loop hypothesis of memory span (Baddeley, 1986), subjects recall items from a decaying phonological store that is refreshed by a covert articulatory process. The rate of covert articulation is said to determine memory span. The present research indicates that this account underemphasizes effects of (1) other covert mnemonic processes and (2) overt pronunciation in recall. Memory span and maximal speech rate for sets of one-, two-, and three-syllable words were examined in groups of children with mean ages of 4;5 and 8;8. Although the usual linear relation between the maximal speech rate and memory span was replicated, speech timing measurements based on the memory responses revealed that age and word length effects had different effects on the timing of responding. Whereas word length affected the duration of words in the response but not silent intervals, age affected the duration of silent, preparatory and interword intervals in the response but not the duration of words. These results are discussed in light of the hypothesis that the speeds of multiple, mnemonically relevant covert and overt processes affect memory span.

Time window and unit capacity: dual constraints on the acquisition of serial information in songbirds

Hand raised nightingales (Luscinia megarhynchos) perform imitations of song-types that were serial neighbours in a string of master song-types sequentially associated as “packages” of limited size. This study examines whether such “chunking” of auditorily perceived serial information can be influenced by the presentation rate of stimuli. Subjects (n = 8 males) were exposed to 3 different tutoring regimes, designed to offer either a “normal”, or a “dense”, or a “spaced” distribution of information (measure: number of songs per unit time): The duration of silent intervals separating subsequent songs in a string of master song-types was 4 s (“normal”), 1 s (“dense”) or 10 s (“spaced”). The analysis of packages of acquired song-types revealed the following results: The results confirm an earlier hypothesis predicting that the formation of song-type packages is mediated by a process which parses strings of auditorily perceived information upon exposure to serial stimuli. In addition, the results suggest that the parsing of a song-type string is controlled by two components: a unit (or information) based capacity buffer (evidence: constraints during “dense”), and a time window based gating mechanism (evidence: constraints during “spaced”).

Dynamic specification of coarticulated vowels spoken in sentence context.

According to a dynamic specification account, coarticulated vowels are identified on the basis of time-varying acoustic information, rather than solely on the basis of "target" information contained within a single spectral cross section of an acoustic syllable. Three experiments utilizing digitally segmented portions of consonant-vowel-consonant (CVC) syllables spoken rapidly in a carrier sentence were designed to examine the relative contribution of (1) target information available in vocalic nuclei, (2) intrinsic duration information specified by syllable length, and (3) dynamic spectral information defined over syllable onsets and offsets. In experiments 1 and 2, vowels produced in three consonantal contexts by an adult male were examined. Results showed that vowels in silent-center (SC) syllables (in which vocalic nuclei were attentuated to silence leaving initial and final transitional portions in their original temporal relationship) were perceived relatively accurately, although not as well as unmodified syllables (experiment 1); random versus blocked presentation of consonantal contexts did not affect performance. Error rates were slightly greater for vowels in SC syllables in which intrinsic duration differences were neutralized by equating the duration of silent intervals between initial and final transitional portions. However, performance was significantly better than when only initial transitions or final transitions were presented alone (experiment 2). Experiment 3 employed CVC stimuli produced by another adult male, and included six consonantal contexts. Both SC syllables and excised syllable nuclei with appropriate intrinsic durations were identified no less accurately than unmodified controls. Neutralizing duration differences in SC syllables increased identification errors only slightly, while truncating excised syllable nuclei yielded a greater increase in errors. These results demonstrate that time-varying information is necessary for accurate identification of coarticulated vowels. Two hypotheses about the nature of the dynamic information specified over syllable onsets and offsets are discussed.

音の持続時間 無音区間の言語識別能に及ぼす影響

音の持続時間 無音区間の言語識別能に及ぼす影響

Perception of duration of medial silent intervals in speech and nonspeech signals

Vowels are longer before voiced consonants than before voiceless consonants, and a number of studies have demonstrated that perception of voicing, in syllable‐final and intervocalic positions, is in accordance with this production regularity. We present a study, using nonspeech stimuli, that suggests that this agreement between production and perception for segmental duration is grounded in auditory processing of complex stimuli in general. Two types of square‐wave analogs, modeled after a speech series ranging from “aba” to “apa” were constructed. The two nonspeech stimulus series varied in duration of a silent interval from 20–110 ms bounded by frequency transitions out of and into steady‐state segments. One series had an initial segment duration of 155 ms, whereas, the initial segment duration of the other series was 245 ms. Duration of the final segment was 188 ms for both series. Listeners judged significantly more of these nonspeech stimuli to be similar to the short silent interval endpoint when the initial segment was long than when the initial segment was short. This result parallels the finding for speech that listeners perceived more voiced /b/ than voiceless /p/ consonants following longer vowels. These results call into question explanations of this production/perception concordance that suggest either mediation of perception by knowledge of production regularities, or direct perception or articulation. [Work supported by NICHHD.]

Perceptual assessment of the intervocalic formant transition place cues of /s/ in /sɪsi/ and /sɪsɑ/

This is an extension of the investigator's previous work [J. Acoust. Soc. Am. Suppl. 1 71, S105; and 72, S16 (1982)]. A series of spoken /sɪsi,sisɑ/ tokens was modified using a PCM speech editor. The /s/‐noise segments were excised. The original intervocalic /ɪ‐i,ɪ‐ɑ/ contexts and the /ɪ,i,ɑ/ vowels in isolation were assembled into a perceptual identification test and low‐pass filtered at 3 kHz with an attenuation slope of 48 dB/oct. As a consequence, the noise and transient energy coextensive in time but higher in frequency than the vocalic formant structures was removed more completely than before. Subjects identified the consonants heard adjacent to the vocalic segments. There was better agreement as to the labial stop frequently heard in the intervocalic /ɪ‐i/ context than previously. As before, dental‐alveolar stops were frequency heard in /ɪ‐ɑ/. These results reflect perceptual integration over the arresting and releasing transition and silent interval duration cues. [Haskins Laboratories provided valuable assistance in the preparation of stimuli on NIGHD Contract No. NIH‐71‐2420.]

Information in speech: observations on the perception of [s]-stop clusters.

A series of experiments is reported that investigated the pattern of acoustic information specifying place and manner of stop consonants in medial position after [s]. In both production and perception, information for stop place includes the spectrum of the fricative at offset, the duration of the silent closure interval, the spectral relationship between the frequency of the stop release burst and the following periodically excited formants, and the spectral and temporal characteristics of the first formant transition. Similarly, the information for stop manner includes the duration of silent closure, the frequency of the first formant at the release, the magnitude of the first formant transition, and the proximity of the second and third formants at release. A relationship was shown to exist in perception between the spectral characteristics of the first formant and the duration of the silent closure required to hear a stop. This appears to reciprocate the covariation of these parameters in production across different places of articulation and different vocalic contexts. The existence of perceptual sensitivity to a wide range of the acoustic consequences of production questions the efficacy of accounts of speech perception in terms of the fractionation of the signal into elemental acoustic cues, which are then integrated to yield a phonetic percept. It is argued that it is inappropriate to ascribe a psychological status to cues whose only reality is their operational role as physical parameters whose manipulation can change the phenotic interpretation of a signal. It is suggested that the metric of the information for phonetic perception cannot be that of the cues; rather, a metric should be sought in which acoustic and articulatory dynamics are isomorphic.