Michael P. Robb

Phonatory characteristics of Parkinsonian speech before and after morning medication: the ON and OFF states

UNLABELLED After prolonged treatment with L-dopa, patients with Parkinsons disease (PD) experience fluctuations in motor performance. Changes in voice production have been documented perceptually during periods of fluctuation, but few quantitative changes have been found. The purpose of this study is to examine the acoustic-phonatory characteristics of PD speech before and after taking medication, to determine if fluctuations affected phonation. Nine PD patients participated in this study. Multiple analyses were performed, and revealed that fundamental frequency (Fo) variability in vowels and mean Fo were higher, while intensity range was lower in PD patients compared to controls. When the PD subjects were examined after versus before medication, group differences were small, but phonatory improvements were seen in individual subjects. Discussion focuses on physiological changes and variability in PD, and implications of response fluctuations to speech production. LEARNING OUTCOMES As a result of this activity, the participant will be able to (1) acquire knowledge and understanding of PD and the voice characteristics commonly associated with PD and (2) understand the effects of L-dopa-related fluctuations on voice production in PD.

Consonant inventories of young children from 8 to 25 months

The results of a longitudinal study of seven childrens consonant production are reported. Data were collected at monthly intervals between the ages of 8 and 25 months. All glossable and non-glossable utterances that occurred during data collection were combined to determine: (1) the number and types of consonants occurring in the childrens syllable-initial and syllable-final inventories, and (2) the relative frequency of occurrence of the major manner and place sound classes. The results were comparable to those of previous investigations, although slightly larger and more diverse consonant types were noted in the childrens earliest monthly inventories. The advantages of considering non-glossed vocalizations when assessing a young childs phonetic abilities are discussed.

Influence of Gender and Environmental Setting on Voice Onset Time

The influence of gender and environmental setting on voice onset time (VOT) was examined. Participants produced six stop consonants paired with three vowels in a consonant + vowel (CV) context. Recordings were made when participants were seated inside a sound booth (laboratory setting) and outside a sound booth (non-laboratory setting). Results of the analysis for VOT and CV duration indicated that females produced voiceless stops with significantly longer VOT durations than males in both settings. Both gender groups produced CV tokens with significantly longer duration in the laboratory setting; however, females continued to produce CV tokens with longer duration in the non-laboratory setting. Findings suggest that differences in the vocal anatomy between genders may account for some but not all differences in temporal measures of speech production. Sociophonetic factors, such as speaking style, may also contribute to gender differences in speaking behavior.

A study of sentence stress production in Mandarin speakers of American English

Acoustic characteristics of American English sentence stress produced by native Mandarin speakers are reported. Fundamental frequency (F0), vowel duration, and vowel intensity in the sentence-level stress produced by 40 Mandarin speakers were compared to those of 40 American English speakers. Results obtained from two methods of stress calculation indicated that Mandarin speakers of American English are able to differentiate stressed and unstressed words according to features of F0, duration, and intensity. Although the group of Mandarin speakers were able to signal stress in their sentence productions, the acoustic characteristics of stress were not identical to the American speakers. Mandarin speakers were found to produce stressed words with a significantly higher F0 and shorter duration compared to the American speakers. The groups also differed in production of unstressed words with Mandarin speakers using a higher F0 and greater intensity compared to American speakers. Although the acoustic differences observed may reflect an interference of L1 Mandarin in the production of L2 American English, the outcome of this study suggests no critical divergence between these speakers in the way they implement American English sentence stress.

Audibility and recognition of stop consonants in normal and hearing-impaired subjects

The purpose of this study was to examine the effect of spectral-cue audibility on the recognition of stop consonants in normal-hearing and hearing-impaired adults. Subjects identified six synthetic CV speech tokens in a closed-set response task. Each syllable differed only in the initial 40-ms consonant portion of the stimulus. In order to relate performance to spectral-cue audibility, the initial 40 ms of each CV were analyzed via FFT and the resulting spectral array was passed through a sliding-filter model of the human auditory system to account for logarithmic representation of frequency and the summation of stimulus energy within critical bands. This allowed the spectral data to be displayed in comparison to a subjects sensitivity thresholds. For normal-hearing subjects, an orderly function relating the percentage of audible stimulus to recognition performance was found, with perfect discrimination performance occurring when the bulk of the stimulus spectrum was presented at suprathreshold levels. For the hearing-impaired subjects, however, it was found in many instances that suprathreshold presentation of stop-consonant spectral cues did not yield recognition equivalent to that found for the normal-hearing subjects. These results demonstrate that while the audibility of individual stop consonants is an important factor influencing recognition performance in hearing-impaired subjects, it is not always sufficient to explain the effects of sensorineural hearing loss.

Vocal fundamental frequency characteristics during the first two years of life

Vocal fundamental frequency (Fo) characteristics were sampled for a group of seven young children. The children were followed longitudinally for a 12-month period, spanning preword, single-word, and multiword vocalizations. The Fo characteristics were analyzed with reference to chronological age, vocalization length, and lexicon size. Measures of average Fo and Fo variability changed little during the 12-month period for each child. A rising-falling intonation contour was the most prevalent Fo contour among the children. In general, the influence of vocalization length and language acquisition on measures of Fo was negligible. It is suggested that relative uniformity in vocal Fo exists in early vocalizations across preword and meaningful speech periods.

Acoustic observations in young children’s non‐cry vocalizations

A corpus of 1200 non-cry vocalization samples produced by 14 normal children between the ages of 11-25 months was examined retrospectively. Six percent of the samples yielded instances of either harmonic doubling (HD), fundamental frequency (F0) shift, or biphonation (Bp). These spectrographic features relate to short duration changes in F0, reflecting alterations in vocal fold state characteristics. The HD and Bp segments were perceptually judged to be harsh, while F0 shift closely reflected pitch breaks. The frequency of occurrence of the three acoustic features suggests that they are normally occurring phonatory events in normal childrens vocal patterns.

The Effect of Effortful Swallow on Pharyngeal Manometric Measurements During Saliva and Water Swallowing in Healthy Participants

OBJECTIVE To evaluate the effect of effortful swallow on pharyngeal manometric pressure measurements during saliva and water swallowing. DESIGN Comparative analysis of pharyngeal pressure generation under 2 bolus and 2 task conditions. SETTING Swallowing rehabilitation research laboratory. PARTICIPANTS Healthy participants (N=40), sex equally represented, with a mean age of 25.8 years. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Manometric peak and nadir amplitude and duration measures at 3 locations in the pharynx. RESULTS Significantly higher peak pressures were measured for saliva swallows compared with water swallows under both swallowing conditions at the proximal pharyngeal sensor only (P=.011). No significant differences were observed between the effortful versus noneffortful conditions at the proximal and midpharyngeal sensors; however, upper esophageal sphincter (UES) nadir pressures were significantly lower for effortful than noneffortful swallows (P=.034) with significantly lower pressure measurements in saliva effortful swallows (P=.008) compared with water effortful swallows. Saliva swallows resulted in significantly longer pressure durations than water swallows at the proximal (P=.003) and middle (P=.048) sensors. Pressure-generation duration was significantly longer in effortful versus noneffortful swallows for the middle sensor (P=.036) only. CONCLUSIONS The results indicate that the effect of effortful swallow on pharyngeal peak pressure measurement is not altered by bolus type (saliva vs water). However, this is not the case for nadir pressure measurements in the UES, which were significantly lower in effortful saliva swallows than in effortful water swallows.

Estimation of formant frequencies in infant cry

The formant frequencies (F1, F2, F3) of normal infant crying were measured using three different estimation techniques: sound spectrography, linear predictive coding (LPC), and power spectrum analysis. Results found all three techniques to be highly similar for estimation of F1. However, the techniques differed significantly in the estimation of F2 and F3. Power spectrum analysis tended to yield the highest F2 and F3 values, while LPC consistently provided the lowest F2 and F3 values. Based on the results of the study, serious questions arise whether formant estimates of cry are accurate or appropriate for use as a metric of infant vocal tract resonance.

Vocal Tract Resonance Characteristics of Adults with Obstructive Sleep Apnea

Vocal tract acoustic resonance was evaluated in a group of 10 untreated adult males with diagnosed obstructive sleep apnea (OSA) syndrome compared to 10 non-OSA adult males. Subjects were required to prolong the vowels /i/, /u/ and /a/, which were subsequently submitted to acoustic analysis of formant frequency and formant bandwidth. Results of the formant frequency analysis indicated lower formant values among the OSA group compared to the non-OSA group, for each vowel type. The lower formant frequencies among the OSA group were attributed to greater vocal tract length compared to non-OSA speakers. The corresponding formant bandwidths for each vowel produced by the OSA group were significantly wider compared to the non-OSA group. The wide formant bandwidths were interpreted to reflect significantly greater vocal tract damping in the OSA subjects, resulting from either excessive vocal tract tissue compliance or general size differences in the length and cross-sectional area of the vocal tract. Discussion focuses on the potential applications of acoustic analysis to aid in the diagnosis and follow-up treatment of OSA.