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PubMed1993

Relationships between acoustically determined knowledge of stop place and voicing contrasts and phonological treatment progress.

The speech of 7 children with phonological disorders (4 who failed to produce an initial voicing contrast for stops and 3 who failed to produce the alveolar-velar stop contrast) was analyzed for imperceptible acoustic distinctions for seemingly homophonous word pairs. Subjects were audio/video recorded before and during treatment as they produced minimal pairs containing their error and correct sound. Acoustic measures were VOT and CV locus equations. The presence of acoustic distinctions was taken as evidence for productive knowledge of the sound contrasts. Treatment was applied experimentally and progress was related to pretreatment productive knowledge inferred from acoustic distinctions. A shorter treatment period was observed for subjects attributed to have productive knowledge of the contrast being trained, as compared with those who had no knowledge. One of the 4 subjects with initial voicing errors produced an acoustic distinction between voiced and voiceless stops and required the shortest treatment period to establish the voicing contrast. Two of 3 subjects with velar fronting displayed coarticulatory characteristics of velars and required fewer treatment sessions in comparison with the subject with no such characteristics. Results are discussed in reference to other linguistic and nonlinguistic variables from which to predict treatment outcomes.

Articulation Disorders↗
PubMed1993

The influence of noise on the measured amplitudes of distortion-product otoacoustic emissions.

This paper describes the influence of noise on the measured amplitudes of tonal signals, as determined using narrowband spectral analysis, that is, the technique typically used to measure distortion-product otoacoustic emissions (DPOAEs). At small signal-to-noise ratios, background noise results in overestimation of DPOAE amplitude and, thus, substantially influences the measured properties of the low-level portions of DPOAE-growth functions, in particular the apparent slope of the functions in this region. It is shown that, because of the influence of noise, the algorithm for the objective estimation of detection thresholds of DPOAEs, and of the slopes of DPOAE-growth functions, described by Nelson and Kimberley (1992), will tend to underestimate these values. This systematic underestimation is presumably the reason why many of the DPOAE-detection thresholds and growth slopes presented in that study were considerably lower than those reported in previous studies using similar measuring equipment and paradigms but different detection-threshold and growth-slope estimation techniques. In the present paper, a simple equation allowing an estimated correction for the effects of noise on measured DPOAE amplitudes is presented. Finally, an alternative strategy for the estimation of DPOAE thresholds, one that is less prone to the influence of noise, is suggested.

Acoustic Stimulation↗
PubMed1993

The emergence of mature gestural patterns is not uniform: evidence from an acoustic study.

Previous studies investigating the organization of articulatory gestures present conflicting accounts of age-related differences in the execution of the articulatory gestures themselves and in the organization of those gestures. Several methodological differences may help to explain these contradictions: First, different studies have used different measures, all of which reflect vocal-tract activity to varying extents; second, the articulatory gestures being analyzed differed across studies; third, the phonetic composition of syllables has varied; and finally, utterance length, and therefore complexity, has varied across studies. The purpose of this study was to investigate the possibility that the reason these methodological differences have led to contradictory results is because the emergence of mature gestural patterns in children's speech is not uniform. To accomplish this goal, detailed acoustic analyses were performed on schwa-stop-vowel utterances from adults and from children (3, 5, and 7 years of age). Temporal measures showed that some acoustic segments were longer in children's than in adults' samples, whereas others were similar in duration. Formant frequencies indicated that vocal-tract opening and closing achieve adult-like patterns of movement by the age of 3 years, but children's tongue gestures are constrained by phonetic context more than those of adults until at least the age of 7 years. Taken together, these results suggest that the pace of development for learning to produce and to coordinate articulatory gestures is not uniform. Thus, the contradictions in findings among earlier studies may very well reflect differences in choices of measurement and utterances to be analyzed, both of which may lead to evaluations of different aspects of gestural patterning.

Adult↗
PubMed1993

Characteristics of speaking rate in the dysarthria associated with amyotrophic lateral sclerosis.

The ability to alter speaking rate was studied in a group of 9 subjects with amyotrophic lateral sclerosis (ALS) and 9 age- and gender-matched, neurologically intact controls. Subjects were instructed to speak at three different rates (i.e., habitual, twice as fast as habitual, and one-half as fast as habitual). Speaking rate, articulation rate, and pause duration and frequency were calculated. The proportional increase in speaking rate was similar between the groups; however, the dysarthric speakers slowed rate to a smaller extent. Articulation rate and pause duration and frequency covaried with speaking rate in a similar manner for both groups. There was evidence that dysarthric speakers showed a greater dependence on pause duration and frequency, as compared to articulation rate, especially when increasing rate. In addition, although it was found that the slope of the function relating phrase duration to phrase length in syllables was statistically significant for both normal and dysarthric speakers, the slope of the function was significantly more shallow for the dysarthric speakers. Perceptual judgments of speaking rate indicated that dysarthric speakers spoke faster for a given physical speaking rate. Finally, results suggested that the function relating physical to perceived speaking rate grew more rapidly for dysarthric as compared to normal speakers. Discussion focuses on the importance of these findings to rate manipulation therapies and models of speaking rate in dysarthric speech.

Adult↗
PubMed1994

Intelligibility and the acoustic characteristics of speech in amyotrophic lateral sclerosis (ALS).

The purpose of this study was to analyze the changes in specific speech parameters in 14 patients, 7 dysarthric and 7 non-dysarthric, with amyotrophic lateral sclerosis (ALS), over a 6-month period. Measurements of single word intelligibility, F2 formant trajectories (extent, duration and rate) and diadochokinetic rate showed decreased performance in dysarthric patients as compared to non-dysarthric patients at baseline. F2 transition rates of less than 4 Hz/msec were seen only in dysarthric ALS patients. A relationship between the F2 transition rate and single word intelligibility was noted for patients with moderate to high intelligibility, but at lower levels of intelligibility the F2 rate reached a plateau despite continued decline in intelligibility. Our results support the need for frequent evaluation of dysarthric ALS patients to better understand the relationship between intelligibility and the acoustic parameters of speech.

Adult↗
PubMed1994

Masking of speech in young and elderly listeners with hearing loss.

This study examined the contributions of various properties of background noise to the speech recognition difficulties experienced by young and elderly listeners with hearing loss. Three groups of subjects participated: young listeners with normal hearing, young listeners with sensorineural hearing loss, and elderly listeners with sensorineural hearing loss. Sensitivity thresholds up to 4000 Hz of the young and elderly groups of listeners with hearing loss were closely matched, and a high-pass masking noise was added to minimize the contributions of high-frequency (above 4000 Hz) thresholds, which were not closely matched. Speech recognition scores for monosyllables were obtained in the high-pass noise alone and in three noise backgrounds. The latter consisted of high-pass noise plus one of three maskers: speech-spectrum noise, speech-spectrum noise temporally modulated by the envelope of multi-talker babble, and multi-talker babble. For all conditions, the groups with hearing impairment consistently scored lower than the group with normal hearing. Although there was a trend toward poorer speech-recognition scores as the masker condition more closely resembled the speech babble, the effect of masker condition was not statistically significant. There was no interaction between group and condition, implying that listeners with normal hearing and listeners with hearing loss are affected similarly by the type of background noise when the long-term spectrum of the masker is held constant. A significant effect of age was not observed. In addition, masked thresholds for pure tones in the presence of the speech-spectrum masker were not different for the young and elderly listeners with hearing loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Acoustic correlates of breathy vocal quality.

The purpose of this study was to evaluate the effectiveness of several acoustic measures in predicting breathiness ratings. Recordings were made of eight normal men and seven normal women producing normally phonated, moderately breathy, and very breathy sustained vowels. Twenty listeners rated the degree of breathiness using a direct magnitude estimation procedure. Acoustic measures were made of: (a) signal periodicity, (b) first harmonic amplitude, and (c) spectral tilt. Periodicity measures provided the most accurate predictions of perceived breathiness, accounting for approximately 80% of the variance in breathiness ratings. The relative amplitude of the first harmonic correlated moderately with breathiness ratings, and two measures of spectral tilt correlated weakly with perceived breathiness.

Adult↗
PubMed1994

Analysis of vocal disorders with methods from nonlinear dynamics.

Several authors have recently demonstrated the intimate relationship between nonlinear dynamics and observations in vocal fold vibration (Herzel, 1993; Mende, Herzel, & Wermke, 1990; Titze, Baken, & Herzel, 1993). The aim of this paper is to analyze vocal disorders from a nonlinear dynamics point of view. Basic concepts and analysis techniques from nonlinear dynamics are reviewed and related to voice. The voices of several patients with vocal disorders are analyzed using traditional voice analysis techniques and methods from nonlinear dynamics. The two methods are shown to complement each other in many ways. Likely physiological mechanisms of the observed nonlinear phenomena are presented, and it is shown how much of the terminology in the literature describing rough voice can be unified within the framework of nonlinear dynamics.

Electroencephalography↗
PubMed1994

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.

Age Factors↗
PubMed1994

A structured approach to voice range profile (phonetogram) analysis.

A new method to analyze voice range profiles (phonetograms) is described. The structured analysis is based on quantitatively determining the features: shape, area, and "speaking range" dynamics, without distorting the shape of phonetograms. The parameter sets describing these features are calculated independently of fundamental frequency, which makes it possible to compare phonetograms. Two phonetograms representing a normal and a pathological example are used to illustrate the proposed method. The process provides a tool for establishing normative data for specified groups.

Female↗
PubMed1994

Duration of function-word vowels in mothers' speech to young children.

The purpose of this investigation was to determine whether function words are lengthened in certain phrase positions in mother-to-child speech. Twenty-two mother-child dyads served as subjects. All children (ages 1:5 to 2:2) had a mean length of utterance between 1.0 and 1.5 morphemes. Each mother was asked to read five experimental stories aloud to her child and to an adult. The durations of seven function-word vowels in these stories were examined. Each word appeared in three phrase positions (phrase-initial, phrase-medial, and two types of phrase-final). Function-word vowels in initial and medial positions did not differ significantly in adult-directed and child-directed speech. In contrast, function-word vowels in final position were significantly longer in mothers' speech to their children.

Child Language↗
PubMed1995

Time-frequency analyses of thyroarytenoid myoelectric activity in normal and spasmodic dysphonia subjects.

Digital recordings of thyroarytenoid (TA) myoelectric activity (via percutaneous hooked-wire electrodes) were obtained for 10 normal control subjects and 10 subjects with spasmodic dysphonia during performance of five tasks of varying complexity: quiet breathing, Valsalva maneuver, whispered /i/, voiced /i/, and "beep beep went the heap." Time-frequency power spectral density functions, PSD(f,t), were determined for a selected segment of the signals, and measures of median frequency, mean frequency, bandwidth, and center frequency of PSD(f,t) were derived for each sample point. Statistical median, mean, standard deviation, minimum, maximum, and mode of the power spectral density measures were computed to compose feature vectors for each TA myoelectric recording. Statistical pattern recognition procedures using maximum likelihood classification tests were applied to the feature space to discriminate disordered from normal speakers for each task. Findings indicate a high level of discriminability between subject groups for phonated speaking tasks in contrast to low levels of discriminability for whispered and nonspeech tasks. Graphical presentations of three-dimensional PSD(f,t) plots are given that illustrate changes in spectral characteristics of TA EMG at the onset of laryngospasm.

Adult↗
PubMed1995

Acoustic correlates of stress in young children's speech.

This study examined the acoustic correlates of stress in children's productions of familiar words. Previous research has employed experimental words rather than familiar words to examine children's phonetic marking of stress, or has not adequately controlled for phonetic environment. Subjects in this study included 22 children, aged 18-30 months, and 6 adults. Fundamental frequency, duration, and amplitude measures were extracted from stressed and unstressed syllables in two types of comparisons: one that controlled phonetic environment and syllable position (interword) and one that measured the relative effects of stress within the same word (intraword). When the tokens were analyzed on the basis of target stress pattern, results revealed no differences between adults and children in their acoustic marking of stress. Listener judgments showed that approximately 30% of children's two-syllable productions were coded unreliably or were perceived as inaccurately stressed. Overall findings indicate that children control fundamental frequency, amplitude, and duration to derive perceptually identifiable stress contrasts in the majority of their productions but they are not completely adult-like in their marking of stress.

Adult↗
PubMed1995

Acoustic correlates of inspiratory phonation during infant cry.

The duration and vocal fundamental frequency (Fo) of inspiratory cries produced by a group of 20 healthy infants were measured. Similar acoustic measures were applied to the cries immediately preceding and following an inspiratory cry as a means of characterizing an inspiratory "event." Results were that the number of inspiratory cries varied considerably from child to child during a complete crying episode. The duration and Fo of inspiratory cries were significantly shorter and higher, respectively, in comparison to cries immediately preceding and following the inspiratory cry. In addition, the gap duration following an inspiratory cry was significantly greater than the pre-inspiratory gap duration. Discussion centers on the anatomical and physiological bases of inspiratory cry phonation. Implications as well as the need to consider the inspiratory portion of crying behavior when examining infants at risk for respiratory distress also are discussed.

Crying↗
PubMed1995

Comparisons among aerodynamic, electroglottographic, and acoustic spectral measures of female voice.

This study examines measures of the glottal airflow waveform, the electroglottographic signal (EGG), amplitude differences between peaks in the acoustic spectrum, and observations of the spectral energy content of the third formant (F3), in terms of how they relate to one another. Twenty females with normal voices served as subjects. Both group and individual data were studied. Measurements were made for the vowel in two speech tasks: strings of the syllable /pae/and sustained phonation of /ae/, which were produced at two levels of vocal effort: comfortable and loud voice. The main results were: 1. Significant differences in parameter values between /pae/and/ae/were related to significant differences in the sound pressure level (SPL). 2. An "adduction quotient," measured from the glottal waveform at a 30% criterion, was sensitive enough to differentiate between waveforms reflecting abrupt versus gradual vocal fold closing movements. 3. DC flow showed weak or nonsignificant relationships with acoustic measures. 4. The spectral content in the third formant (F3) in comfortable loudness typically consisted of a mix of noise and harmonic energy. In loud voice, the F3 spectral content typically consisted of harmonic energy. 5. Significant differences were found in all measures between tokens with F3 harmonic energy and tokens with F3 noise, independent of loudness condition. 6. Strong relationships between flow- and EGG-adduction quotients suggested that these signals can be used to complement each other. 7. The amplitude difference between spectral peaks of the first and third formant (F1-F3) was found to add information about abruptness of airflow decrease (flow declination) that may be lost in the glottal waveform signal due to low-pass filtering. The results are discussed in terms of how an integrated use of these measures can contribute to a better understanding of the normal vocal mechanism and help to improve methods for evaluating vocal function.

Adult↗
PubMed1996

Labelling and discrimination of a synthetic fricative continuum in noise: a study of absolute duration and relative onset time cues.

Categorical perception was evaluated for a nine-token voice onset time (VOT) continuum with endpoint tokens /feil/-/veil/. The synthetic speech continuum was presented in a random-level noise masker at different signal-to-noise ratios (SNR = 0, + 6, +12 dB) and overall presentation levels (50 and 70 dB HL). Overall labelling performance deteriorated as the SNR was reduced. Labelling results for the +12-dB-SNR condition reflected a category boundary at 87 ms for listeners with normal hearing sensitivity. The companion two-step discrimination function revealed better-than-chance performance between pairs of tokens labelled fail, chance performance between pairs of tokens labelled vail, and a slight performance peak at the labelling boundary between fail and vail. Listeners with high-frequency audiometric deficits produced labelling results for the +12-dB-SNR condition that were similar to normal functions measured for the 0-dB-SNR condition. These listeners were unable to discriminate two-step differences in voicing duration, but they produced a normal temporal labelling boundary. To try to understand the noncategorical discrimination data, a psychoacoustic analog for the speech continuum was evaluated. Relative onset time (ROT) difference limens (DLs) were measured as a function of the temporal onset delay of a low-frequency sawtooth waveform relative to the onset of a high-frequency noise burst. The ROT cue was used only when absolute stimulus duration could not be relied upon as a consistent cue, under conditions where a large range of random overall duration was presented to the listener. The ROT DLs were relatively invariant over a range of standard delays from 50 to 110 ms. The average DL was about 30 ms, which is consistent with the small performance peak in the synthetic speech discrimination function.

Humans↗
PubMed1996

A subharmonic vibratory pattern in normal vocal folds.

This study observes in detail an F0/2 (sounding an octave below an original tone) subharmonic vibratory pattern produced in a normal larynx. Simultaneous electroglottographic and photoglottographic measurements reveal two different open phases within a subharmonic cycle- the first shorter with a simple shape, the second longer with a shape containing a "ripple." Such parameters as the large open quotient (ca. 0.8) and the high airflow values (ca. 1000 cm3/s) distinguish this phonation from the vocal fry (pulse) register. Using an electronic divider to track the subharmonic frequency, a method has been developed to observe the subharmonic vibration of the vocal folds stroboscopically. The stroboscopic visualization reveals an unusual mucosal movement during the "ripple," characterized by an opening movement of the upper margins, which interrupts the closing movement of the vocal folds. An explanation is offered that this vibratory pattern arises as a consequence of detuning of the usually identical frequencies of the dominant modes of the vocal folds, with 3:2 entrainment replacing the normal 1:1 pattern.

Humans↗