Virginia Wolfe

Acoustic correlates of dysphonia: type and severity

The purpose of this study was to explore the acoustic discrimination and graded severity of three clinical voice types. Listeners classified 102 samples of dysphonic vowels /a/ and /i/ on the basis of voice types: breathy, hoarse, and strained. The vowels were analyzed acoustically with two measures of perturbation and 2 measures of spectral noise. Discriminant analysis showed that apriori, acoustic classifications of voice type were made with 92% accuracy using four acoustic parameters: (a) cepstral peak prominence (CPP), (b) jitter standard deviation (SD-J), (c) fundamental frequency (F0), and (d) standard deviation of signal-to-noise ratio (SD-SNR). Findings suggest that voice type is associated with the interaction of spectral noise, fundamental frequency, and signal irregularity, and that dysphonic severity is associated with similar parameters, regardless of voice type.

Voice problems and risk factors among aerobics instructors

Fifty female and four male aerobics instructors completed a questionnaire pertaining to vocal problems and variables that could indicate an increased risk for developing problems. The questions concerned teaching experience, physical data regarding instructional facilities, method of voice projection, music volume, history of illness, allergies, voice loss, hoarseness, smoking habits, and knowledge of vocal hygiene. The results showed that a significant number of instructors experienced partial or complete voice loss (44%) during and after instructing, as well as increased episodes of voice loss, hoarseness, and sore throat unrelated to illness since they began instructing. Significant variables associated with voice problems included sore throat and hoarseness following instruction, and shouting to cue the participants. It was also found that very few instructors in this study had any knowledge of vocal hygiene techniques.

Acoustic Measures of Dysphonic Severity across and within Voice Types

The purpose of the study was to explore an interaction between pathologic voice type and the acoustic prediction of dysphonic severity. One hundred and two phonatory samples, representing a wide range of laryngeal conditions, were categorized by listeners into three voice types: breathy, rough, and hoarse. A second group of trained listeners rated the severity of the samples on a 7-point scale. Twenty-five frequency- and time-domain measures were used to predict perceptual severity. Multiple regression analyses showed that the most useful measure for the prediction of severity across voice types was noise-to-harmonic ratio (NHR). The severity of individual voice types was predicted with differential results on the basis of both short- and long-term measures of perturbation.

Vocal parameters of aerobic instructors with and without voice problems.

Aerobic instructors frequently experience vocal fatigue and are at risk for the development of vocal fold pathology. Six female aerobic instructors, three with self-reported voice problems and three without, served as subjects. Measures of vocal function (perturbation and EGG) were obtained before and after a 30-minute exercise session. Results showed that the group with self-reported voice problems had greater amounts of jitter, lower harmonic-to-noise ratios, and less periodicity in sustained vowels overall, but no significant differences in measures of perturbation and EGG were found before and immediately after instruction. Measures of vocal parameters showed that subjects with self-reported voice problems projected with relatively greater vocal intensity and phonated for a greater percentage of time across beginning, middle, and ending periods of aerobic instruction than subjects with no reported voice problems.

Effects of Perceptual Training Based upon Synthesized Voice Signals

28 undergraduate students participated in a perceptual voice experiment to assess the effects of training utilizing synthesized voice signals. An instructional strategy based upon synthesized examples of a three-part classification system: “breathy,” “rough,” and “hoarse,” was employed. Training samples were synthesized with varying amounts of jitter (cycle-to-cycle deviation in pitch period) and harmonic-to-noise ratios to represent these qualities. Before training, listeners categorized 60 pathological voices into “breathy,” “rough,” and “hoarse,” largely on the basis of fundamental frequency. After training, categorizations were influenced by harmonic-to-noise ratios as well as fundamental frequency, suggesting that listeners were more aware of spectral differences in pathological voices associated with commonly occurring laryngeal conditions. 40% of the pathological voice samples remained unclassified following training.