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PubMed1981

Effects of domestication on production and perception of mallard maternal alarm calls: developmental lag in behavioral arousal.

The process of domestication involves intense inbreeding. Field and laboratory studies were conducted to assess the effects of such intense genetic selection on the production and perception of the maternal alarm calls of domestic (Peking) and wild mallard ducks (Anas platyrhynchos). With respect to production, the calls of wild and domestic ducks were comparable in four acoustic features and differed only slightly on two features. With respect to perception, the calls of wild and domestic hens were equally effective in promoting behavioral inhibition in wild and domestic ducklings. Although these data revealed little or no effect of domestication on the structure and function of the maternal alarm call, an unexpected effect was found regarding the domestic ducklings' behavior. Specifically, Pekings showed a greater level of behavioral inhibition than did mallards at 24 hr of age. Further experiments indicated that the differential level of inhibition in the wild and domestic birds reflects a developmental lag in arousal consequent to domestication: 72-hr-old Peking ducklings are behaviorally more aroused than 24-hr-old Peking ducklings and are similar to 24-hr-old mallard ducklings in that respect. This appears to be the first demonstration of behavioral heterochrony, which is believed to be an important mechanism of behavioral evolution.

Animals↗
PubMed1990

Auditory grouping based on fundamental frequency and formant peak frequency.

The perceptual grouping of a four-tone cycle was studied as a function of differences in fundamental frequencies and the frequencies of spectral peaks. Each tone had a single formant and at least 13 harmonics. In Experiment 1 the formant was created by filtering a flat spectrum and in Experiment 2 by adding harmonics. Fundamental frequency was found to be capable of controlling grouping even when the spectra spanned exactly the same frequency range. Formant peak separation became more effective as the sharpness (amplitude of the peak relative to a spectral pedestal) increased. The effect of each type of acoustic difference depended on the task. Listeners could group the tones by either sort of difference but were also capable of resisting the disruptive effect of the other one. This was taken as evidence for the presence of a schema-based process of perceptual grouping and the relative weakness of primitive segregation.

Adult↗
PubMed2001

Loudness constancy with varying sound source distance.

At a listener's ears, sound source power and sound source distance are confounded in measures of acoustic intensity, a physical property long thought to be the primary determinate of loudness. Although the relationship between sound source loudness and power is well known when source distance is fixed, relatively little is known about source loudness under conditions of varying distance. Here we show a robust loudness constancy, similar in many ways to visual size constancy, that results under distance-varying conditions that produce inaccurate estimates of source distance. Our results suggest that the auditory system does not require accurate distance estimates to judge source loudness, even when distance is variable. We offer an alternative explanation of loudness constancy based solely on a reverberant sound energy cue.

Acoustic Stimulation↗
PubMed2001

Transmission loss of sound into incubators: implications for voice perception by infants.

OBJECTIVE: To assess the transmission of sound into incubators as a function of talker position (i.e., standing or sitting), incubator port position (i.e., opened or closed), and center frequency (i.e., 125 to 10,000 Hz in one-third octave steps). The second objective was to estimate the audibility of the human voice inside the incubator. STUDY DESIGN: L(eq) measures of signal transmission loss and motor noise were obtained from two incubators. RESULTS: In general, signal transmission loss was greater for the standing-talker position, with front portholes closed, and for high-frequency spectra. Motor noise was greater with both front portholes closed and for lower-frequency spectra. The greatest signal delivery to an infant would be obtained when the speaker is sitting using a raised vocal effort while the incubator ports are opened. CONCLUSION: Measured signal transmission loss and motor noise characteristics of two incubators suggest that only mid-frequency speech spectra would be audible to infants and only at a speech-to-noise ratio of approximately 5 to 10 dB with a raised vocal effort.

Acoustics↗
PubMed2004

Digital data collection and analysis: application for clinical practice.

Technology for digital speech recording and speech analysis is now readily available for all clinicians who use a computer. This article discusses some advantages of moving from analog to digital recordings and outlines basic recording procedures. The purpose of this article is to familiarize speech-language pathologists with computerized audio files and the benefits of working with those sound files as opposed to using analog recordings. This article addresses transcription issues and offers practical examples of various functions, such as playback, editing sound files, using waveform displays, and extracting utterances. An appendix is provided that describes step-by-step how digital recording can be done. It also provides some editing examples and a list of useful computer programs for audio editing and speech analyses. In addition, this article includes suggestions for clinical uses in both the assessment and the treatment of various speech and language diorders.

Computers↗
PubMed2003

Effects of intensive voice treatment (the Lee Silverman Voice Treatment [LSVT]) on ataxic dysarthria: a case study.

This study examined the effects of intensive voice treatment (the Lee Silverman Voice Treatment [LSVT]) on ataxic dysarthria in a woman with cerebellar dysfunction secondary to thiamine deficiency. Perceptual and acoustic measures were made on speech samples recorded just before the LSVT program was administered, immediately after it was administered, and at 9 months follow-up. Results indicate short- and long-term improvement in phonatory and articulatory functions, speech intelligibility, and overall communication and job-related activity following LSVT. This study's findings provide initial support for the application of LSVT to the treatment of speech disorders accompanying ataxic dysarthria. Potential neural mechanisms that may underlie the effects of loud phonation and LSVT are addressed.

Ataxia↗
PubMed2002

Factors that allow a high level of speech understanding by patients fit with cochlear implants.

Three factors account for the high level of speech understanding in quiet enjoyed by many patients fit with cochlear implants. First, some information about speech exists in the time/amplitude envelope of speech. This information is sufficient to narrow the number of word candidates for a given signal. Second, if information from the envelope of speech is available to listeners, then only minimal information from the frequency domain is necessary for high levels of speech recognition in quiet. Third, perceiving strategies for speech are inherently flexible in terms of the mapping between signal frequencies (i.e., the locations of the formants) and phonetic identity.

Cochlear Implantation↗
PubMed2004

Most comfortable and uncomfortable loudness levels: six decades of research.

This article critically reviews the influence of such factors as psychophysical testing method, stimulus type, and instructional set on most comfortable loudness (MCL) and uncomfortable loudness (UCL) levels. Generally, research indicates that test methods and instructions strongly affect both MCL and UCL while stimulus conditions affect them less substantially. Overall, the data suggest lower reliability for MCL than for UCL and lower reliability for pure-tone MCLs than for speech MCLs. Lower MCLs are typically obtained when measured by an ascending approach, in contrast to a descending approach. Results suggest that audiological efforts should be directed toward the development of a standardized test procedure that yields adequately reliable and valid MCLs and UCLs for routine clinical use.

Audiometry, Pure-Tone↗
PubMed2004

Outer and middle ear status and distortion product otoacoustic emissions in children with sickle cell disease.

The purpose of this study was to investigate distortion product otoacoustic emissions (DPOAEs) and outer/middle ear status in 12 African American children with normal hearing and homozygous sickle cell disease (SCD) and age-, gender-, and ear-matched African American controls. C. R. Downs, A. Stuart, & D. Holbert (2000) reported that DPOAE amplitudes were significantly larger for children with SCD. Because the integrity of the middle ear system directly influences OAE characteristics, it was felt that concurrent investigation of DPOAE amplitudes and outer/middle ear function in children with SCD was warranted. DPOAEs were evoked by 13 primary-tone pairs with f2 frequencies ranging from 1000 to 4500 Hz. Outer/middle ear status was assessed with tympanometry through indices of peak compensated static acoustic admittance, tympanometric width, tympanometric peak pressure, ear canal volume, and middle ear resonance frequency. Tympanograms were recorded with probe-tone frequencies of 226 and 678 Hz. DPOAE amplitudes were significantly larger for children with SCD (p < .05). There were no group differences in any of the middle ear indices (p > .05). These findings suggest that increased DPOAE amplitudes for children with SCD cannot be attributed to differences in outer/middle ear function as assessed with tympanometry.

Acoustic Impedance Tests↗
PubMed2001

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.

Child↗
PubMed2001

Perceptual discrimination of speech sounds in developmental dyslexia.

Experiments previously reported in the literature suggest that people with dyslexia have a deficit in categorical perception. However, it is still unclear whether the deficit is specific to the perception of speech sounds or whether it more generally affects auditory function. In order to investigate the relationship between categorical perception and dyslexia, as well as the nature of this categorization deficit, speech specific or not, the discrimination responses of children who have dyslexia and those of average readers to sinewave analogues of speech sounds were compared. These analogues were presented in two different conditions, either as nonspeech whistles or as speech sounds. Results showed that children with dyslexia are less categorical than average readers in the speech condition, mainly because they are better at discriminating acoustic differences between stimuli belonging to the same category. In the nonspeech condition, discrimination was also better for children with dyslexia, but differences in categorical perception were less clear-cut. Further, the location of the categorical boundary on the stimulus continuum differed between speech and nonspeech conditions. As a whole, this study shows that categorical deficit in children with dyslexia results primarily from an increased perceptibility of within-category differences and that it has a speech-specific component. These findings may have profound implications for learning and re-education.

Adolescent↗
PubMed2001

The intelligibility of time-domain-edited esophageal speech.

The intelligibility of esophageal speech has been shown to be significantly lower than that of normal laryngeal speech. The current study investigated the possibility of enhancing the intelligibility of esophageal speech by manipulating samples in the time domain. Specifically, injection noises and nonphrasal pauses were digitally edited from the speech samples of 5 esophageal talkers. Twenty-five sentences were selected and edited in the time domain and presented to 15 naive listeners who were instructed to write down the words that they heard. The percentage of correct words heard for each sentence was determined and compared across listeners, sentences, and talkers. The overall effect of the editing was a small but significant gain in the intelligibility of the esophageal speech. The improvement in intelligibility, however, depended on the individual talker, the speech material, and the number of editing changes made to a particular sample.

Adult↗
PubMed2001

Is there a relationship between speech and nonspeech auditory processing in children with dyslexia?

A group of 8 young teenagers with dyslexia were compared to age-matched control participants on a number of speech and nonspeech auditory tasks. There were no differences between the control participants and the teenagers with dyslexia in forward and simultaneous masking, nor were there any differences in frequency selectivity as indexed by performance with a bandstop noise. Thresholds for backward masking in a broadband noise were elevated for the teenagers with dyslexia as a group. If this deficit in backward masking had an influence on speech perception, we might expect the perception of "ba" versus "da" to be affected, as the crucial second formant transition is followed by a vowel. On the other hand, as forward masking is not different in the two groups, we would expect the perception of "ab" versus "ad" to be unaffected, as the contrastive second formant transition is preceded by a vowel. Overall speech identification and discrimination performance for these two contrasts was superior for the control group but did not differ otherwise. Thus, the clear group deficit in backward masking in the group with dyslexia has no simple relationship to the perception of crucial acoustic features in speech. Furthermore, the deficit for nonspeech analogues of the speech contrasts (second formants in isolation) was much less marked than for the speech sounds, with 75% of the listeners with dyslexia performing equivalently to control listeners. The auditory deficit cannot therefore be simply characterized as a difficulty in processing rapid auditory information. Either there is a linguistic/phonological component to the speech perception deficit, or there is an important effect of acoustic complexity.

Auditory Threshold↗
PubMed2001

Effects of speaking rate on the control of vocal fold vibration: clinical implications of active and passive aspects of devoicing.

Stevens (1991) has suggested that, while speakers control glottal apertures in producing consonants, the buildup of intraoral pressure during an oral closure creates decreases in transglottal flow, which can, in itself, reduce or halt vocal fold vibrations. The object of this study was to determine whether speakers can take advantage of such pressure effects in controlling the voicing attributes of intervocalic stops. Intraoral pressure, vocal fold vibration (Lx portions of electroglottograms), and electromyographic (EMG) activity of the orbicularis oris inferior were monitored for 6 subjects while they produced at "slow," "normal," and "fast" speaking rates utterances containing intervocalic stops /p/ and /b/. Product-moment correlations between the intervocalic pressure rises and the amplitude contour of Lx showed strong negative relationships at normal-to-fast rates of speech. However, this relationship was not maintained at slower rates, where decreases in the amplitude of Lx sometimes occurred before the onset of EMG activity in the labial adductor. The findings suggest that, at normal-to-fast rates of speech, speakers can use the passive effects of pressure in controlling vocal fold vibration for stop consonants.

Adult↗
PubMed2001

Effects of levodopa on laryngeal muscle activity for voice onset and offset in Parkinson disease.

The laryngeal pathophysiology underlying the speech disorder in idiopathic Parkinson disease (IPD) was addressed in this electromyographic study of laryngeal muscle activity. This muscle activity was examined during voice onset and offset gestures in 6 persons in the early stages of IPD who were not receiving medication. The purpose was to determine (a) if impaired voice onset and offset control for speech and vocal fold bowing were related to abnormalities in laryngeal muscle activity in the nonmedicated state and (b) if these attributes change with levodopa. Blinded listeners rated the IPD participants' voice onset and offset control before and after levodopa was administered. In the nonmedicated state, the IPD participants' vocal fold bowing was examined on nasoendoscopy, and laryngeal muscle activity levels were compared with normal research volunteers. The IPD participants were then administered a therapeutic dose of levodopa, and changes in laryngeal muscle activity for voice onset and offset gestures were measured during the same session. Significant differences were found between IPD participants in the nonmedicated state: those with higher levels of muscle activation had vocal fold bowing and greater impairment in voice onset and offset control for speech. Similarly, following levodopa administration, those with thyroarytenoid muscle activity reductions had greater improvements in voice onset and offset control for speech. In this study, voice onset and offset control difficulties and vocal fold bowing were associated with increased levels of laryngeal muscle activity in the absence of medication.

Adult↗
PubMed2001

An acoustical study of the fricative /s/ in the speech of individuals with dysarthria.

This paper reports on measurements of several acoustic attributes of the fricative consonant /s/ produced in word-initial position by normally speaking adults and by speakers with neuromotor dysfunctions. Several acoustic properties are evaluated: the spectrum shape of the fricative and its amplitude in relation to the following vowel, the presence or absence of voicing, the time variation of the spectrum during the fricative and in the transition to the following vowel, and the presence of inappropriate acoustic patterns preceding the /s/. Some of these properties are based on quantitative measurements of the spectrum of the /s/, and others are based on observations of the time-varying acoustic patterns in spectrograms. For the individuals with dysarthria, deviations of each of these properties from the normal range are interpreted in terms of specific deficits in the control of the speech-production system. For the most part, these parameters are highly correlated with the speakers' overall intelligibility, with the intelligibility of words containing the fricative /s/, and with perceptual ratings of the adequacy of the fricative production. The parameters that show the best correlation with intelligibility and perceptual ratings are (a) measures of deviations from normalcy in the time variation of the acoustic pattern within the consonant and at the consonant-vowel boundary and (b) the spectrum shape of the frication noise. These acoustic parameters are related to deviations in the temporal pattern of control of the articulators in producing fricative-vowel sequences and to lack of fine control of the tongue blade in achieving an appropriate target configuration for the fricative.

Adult↗