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Purpose: The purpose of this study was to determine the vocal fold structural and vibratory symmetries that are important to vocal function and voice quality in a simulated paramedian vocal fold paralysis. Method: A computational kinematic speech production model was used to simulate an exemplar "voice" on the basis of asymmetric settings of parameters controlling glottal configuration. These parameters were then altered individually to determine their effect on maximum flow declination rate, spectral slope, cepstral peak prominence, harmonics-to-noise ratio, and perceived voice quality. Results: Asymmetry of each of the 5 vocal fold parameters influenced vocal function and voice quality; measured change was greatest for adduction and bulging. Increasing the symmetry of all parameters improved voice, and the best voice occurred with overcorrection of adduction, followed by bulging, nodal point ratio, starting phase, and amplitude of vibration. Conclusions: Although vocal process adduction and edge bulging asymmetries are most influential in voice quality for simulated vocal fold motion impairment, amplitude of vibration and starting phase asymmetries are also perceptually important. These findings are consistent with the current surgical approach to vocal fold motion impairment, where goals include medializing the vocal process and straightening concave edges. The results also explain many of the residual postoperative voice limitations.

Purpose: This tutorial is a description of a possible approach to teaching the concept of formants to students in a speech science course, at either the undergraduate or graduate level. The approach is to explain formants as prominent regions of energy in the output spectrum envelope radiated at the lips, and how they arise as the superposition of vocal tract resonances on a source signal. Standing waves associated with vocal tract resonances are briefly explained and standing wave animations are provided. Animations of the temporal variation of the vocal tract, vocal tract resonances, spectra, and spectrograms, along with audio samples are included to provide dynamic demonstrations of the concept of formants. Conclusions: The explanations, accompanying demonstrations, and suggested activities are intended to provide a launching point for understanding formants and how they can be measured, analyzed, and interpreted. As a result, participants should be able to describe the meaning of the term "formant" as it relates to a spectrum and a spectrogram, explain the difference between formants and vocal tract resonances, explain how vocal tract resonances combined with the voice source generate formants, and identify formants in both narrow-band and wide-band spectrograms and track their time-varying patterns with a formant tracking algorithm. [ABSTRACT FROM AUTHOR]

Purpose: This study used a computational vocal tract model to investigate the relationship of diphthong duration and vocal tract movement magnitude to measures of the F2 trajectory in CV words. Method: Three words ("bough," "boy," and "buy") were simulated on the basis of an adult female vocal tract model, in which the model parameters were estimated from audio recordings of a female talker. Model parameters were then modified to generate 35 simulations of each word corresponding to 7 different durations and 5 movement magnitude settings. In addition, these simulations were repeated with vocal tract lengths representative of an adult male and an approximately 6-year-old child. Results: On the basis of univariate analysis, measures of frequency predicted changes in magnitude, and temporal measures predicted changes in speaking rate consistent with the hypothesis. The combined effects of duration and magnitude showed that F2 was more sensitive to changes in magnitude at shorter word durations compared with longer word durations. This finding held across words and vocal tract length. Conclusions: Results suggest that there is an interaction between duration and magnitude that affects the slope of the F2 trajectory. The next step is to relate kinematics to F2 trajectory output using real speakers.

The purpose of this study was to determine whether the threshold of velopharyngeal (VP) coupling area at which listeners switch from identifying a consonant as a stop to a nasal in North American English was different for speech produced by a model based on an adult male, an adult female, and a 4-year-old child. V1CV2 stimuli were generated with a speech production model that encodes phonetic segments as relative acoustic targets imposed on an underlying vocal tract and laryngeal structure that can be scaled according to sex and age. Each V1CV2 was synthesized with a set of VP coupling functions whose maximum area ranged from 0 to 0.1 cm2. Results showed that scaling the vocal tract and vocal folds had essentially no effect on the VP coupling area at which listener identification shifted from stop to nasal. The range of coupling areas at which the crossover occurred was 0.037–0.049 cm2 for the male model, 0.040–0.055 cm2 for the female model, and 0.039–0.052 cm2 for the 4-year-old child model, and overall mean was 0.044 cm2. Calculations of band limited peak nasalance indicated that 85% peak nasalance during the consonant was well aligned with listener responses. [ABSTRACT FROM AUTHOR]

Purpose: Computational modeling was used to examine the consequences of 5 different laryngeal asymmetries on acoustic and perceptual measures of vocal function. Method: A kinematic vocal fold model was used to impose 5 laryngeal asymmetries: adduction, edge bulging, nodal point ratio, amplitude of vibration, and starting phase. Thirty /a/ and /?/ vowels were generated for each asymmetry and analyzed acoustically using cepstral peak prominence (CPP), harmonics-to-noise ratio (HNR), and 3 measures of spectral slope (H1*-H2*, B0-B1, and B0-B2). Twenty listeners rated voice quality for a subset of the productions. Results: Increasingly asymmetric adduction, bulging, and nodal point ratio explained significant variance in perceptual rating (R[superscript 2] = 0.05, p < 0.001). The same factors resulted in generally decreasing CPP, HNR, and B0-B2 and in increasing B0-B1. Of the acoustic measures, only CPP explained significant variance in perceived quality (R[superscript 2] = 0.14, p < 0.001). Increasingly asymmetric amplitude of vibration or starting phase minimally altered vocal function or voice quality. Conclusion: Asymmetries of adduction, bulging, and nodal point ratio drove acoustic measures and perception in the current study, whereas asymmetric amplitude of vibration and starting phase demonstrated minimal influence on the acoustic signal or voice quality.

Purpose: The purpose of this study was to investigate the relation of respiratory forced oscillation to the acoustic characteristics of vocal tremor. Method: Acoustical analyses were performed to determine the characteristics of the intensity and fundamental frequency (F[subscript 0]) for speech samples obtained by Farinella, Hixon, Hoit, Story, and Jones (2006) using a respiratory forced oscillation paradigm with 5 healthy adult males to simulate vocal tremor involving respiratory pressure modulation. The analyzed conditions were sustained productions of /a/ with amplitudes of applied pressure of 0, 1, 2, and 4 cmH[subscript 2]O and a rate of 5 Hz. Results: Forced oscillation of the respiratory system produced modulation of the intensity and F[subscript 0] for all participants. Variability was observed between participants and conditions in the change in intensity and F[subscript 0] per unit of pressure change, as well as in the mean intensity and F[subscript 0]. However, the extent of modulation of intensity and F[subscript 0] generally increased as the applied pressure increased, as would be expected. Conclusion: These findings suggest that individuals develop idiosyncratic adaptations to pressure modulations, which are important to understanding aspects of variability in vocal tremor, and highlight the need to assess all components of the speech mechanism that may be directly or indirectly affected by tremor. (Contains 2 tables and 6 figures.)

Purpose: To relate vocal fold structure and kinematics to 2 acoustic measures: cepstral peak prominence (CPP) and the amplitude of the first harmonic relative to the second (H1-H2). Method: The authors used a computational, kinematic model of the medial surfaces of the vocal folds to specify features of vocal fold structure and vibration in a manner consistent with breathy voice. Four model parameters were altered: degree of vocal fold adduction, surface bulging, vibratory nodal point, and supraglottal constriction. CPP and H1-H2 were measured from simulated glottal area, glottal flow, and acoustic waveforms and were related to the underlying vocal fold kinematics. Results: CPP decreased with increased separation of the vocal processes, whereas the nodal point location had little effect. H1-H2 increased as a function of separation of the vocal processes in the range of 1.0 mm to 1.5 mm and decreased with separation greater than 1.5 mm. Conclusions: CPP is generally a function of vocal process separation. H1*-H2* (see paragraph 6 of article text for an explanation of the asterisks) will increase or decrease with vocal process separation on the basis of vocal fold shape, pivot point for the rotational mode, and supraglottal vocal tract shape, limiting its utility as an indicator of breathy voice. Future work will relate the perception of breathiness to vocal fold kinematics and acoustic measures.

Purpose: The present study was designed to investigate the relation of formant transitions to place-of-articulation for stop consonants. A speech production model was used to generate simulated utterances containing voiced stop consonants, and a perceptual experiment was performed to test their identification by listeners. Method: Based on a model of the vocal tract shape, a theoretical basis for reducing highly variable formant transitions to more invariant formant deflection patterns as a function of constriction location was proposed. A speech production model was used to simulate vowel-consonant-vowel (VCV) utterances for 3 underlying vowel-vowel contexts and for which the constriction location was incrementally moved from the lips toward the velar part of the vocal tract. These simulated VCVs were presented to listeners who were asked to identify the consonant. Results: Listener responses indicated that phonetic boundaries were well aligned with points along the vocal tract length where there was a shift in the deflection polarity of either the 2nd or 3rd formant. Conclusions: This study demonstrated that regions of the vocal tract exist that, when constricted, shift the formant frequencies in a predictable direction. Based on a perceptual experiment, the boundaries of these acoustically defined regions were shown to coincide with phonetic categories for stop consonants.

Purpose: To determine if respiratory and laryngeal function during spontaneous speaking were different for teachers with voice disorders compared with teachers without voice problems. Method: Eighteen teachers, 9 with and [...]

Purpose: To evaluate the effects of intensive voice treatment targeting vocal loudness (the Lee Silverman Voice Treatment [LSVT]) on vowel articulation in dysarthric individuals with idiopathic Parkinson's disease (PD). Method: [...]