Voice quality after carbon dioxide laser and conventional surgery for T1A glottic carcinoma

The different types of small vocal fold tumor therapy allow the preservation of respiration and deglutition; the quality of phonation is the most important criterion for the patient. The aim of the study is to compare vocal function after treatment of T1a tumors by conventional and laser cordectomy. Fifty-seven male patients were included in the study: 27 underwent conventional cordectomy using an external approach, and 30 underwent an endoscopic microscopic laser cordectomy. Videolaryngoscopy was performed for each subject, and the maximal phonation time was measured. Spectrograms were recorded, and a perturbation analysis was performed if a clear harmonic structure was visible. Voices were perceptually rated by two experienced phoniatricians using the GRBAS scale. Even though a slightly better voice was found after conventional surgery throughout the data, no statistically significant difference was measured in the two groups. The data on voice outcome per se do not indicate the selection of one surgical approach over another.     

Voice frequency change in singers and nonsingers

Trained singers and nonsingers vocally shadowed sequences of rapidly changing tones. Tone changes within the sequences were unpredictable in terms of direction and extent of frequency change. Subjects' responses to the shadowing task could be evaluated for accuracy of frequency matching, and for time and speed of voice frequency change. In addition, subjects' transitions between tones could be classified as hit, overshoot, undershoot, or oscillate. The two groups were equally accurate in matching the pitches of tones comprising the sequences. Similarly, pitch lowering was faster than pitch raising for both groups of subjects, while speeds for both lowering and raising increased with increases in size of the interval between tones. However, singers required less time than nonsingers in effecting transitions, apparently because they achieved faster peak speeds and took more direct paths between tones. Implications of the data for physiological and mechanical aspects of voice frequency control are discussed.     

Cancellation of Simulated Environmental Noise as a Tool for Measuring Vocal Performance During Noise Exposure

It can be difficult for the voice clinician to observe or measure how a patient uses his voice in a noisy environment. We consider here a novel method for obtaining this information in the laboratory. Worksite noise and filtered white noise were reproduced over high-fidelity loudspeakers. In this noise, 11 subjects read an instructional text of 1.5 to 2 minutes duration, as if addressing a group of people. Using channel estimation techniques, the site noise was suppressed from the recording, and the voice signal alone was recovered. The attainable noise rejection is limited only by the precision of the experimental setup, which includes the need for the subject to remain still so as not to perturb the estimated acoustic channel. This feasibility study, with 7 female and 4 male subjects, showed that small displacements of the speaker's body, even breathing, impose a practical limit on the attainable noise rejection. The noise rejection was typically 30 dB and maximally 40 dB down over the entire voice spectrum. Recordings thus processed were clean enough to permit voice analysis with the long-time average spectrum and the computerized phonetogram. The effects of site noise on voice sound pressure level, fundamental frequency, long-term average spectrum centroid, phonetogram area, and phonation time were much as expected, but with some interesting differences between females and males.     

Voice disorders in patients with suspected laryngo-pharyngeal reflux disease

Many symptoms have been recognized in association with laryngo-pharyngealreflux disease (LPRD), but reports of perceptual voice disorders in this condition have been lacking to date. Forty-nine patients with suspected LPRD were studied for five specific perceptual voice characteristics, and these characteristics were compared to the same characteristics in individuals who had never seen an Otolaryngologist for a voice disorder or throat problem (controls). Sixteen of the suspected LPRD patients also underwent 24-hour pH probe studies. All patients with suspected LPRD had significantly increased abnormal perceptual voice characteristics (musculoskeletal tension, hard glottal attack, glottal fry, restricted tone placement, and hoarseness) compared to the controls. Statistical objective differences between the two groups was demonstrated by the presence of increased shimmer in patients with suspected LPRD compared to controls. The differential diagnosis between functional voice disorders and LPRD may be complex, and perceptual parameters may overlap. Interdisciplinary evaluation is advocated.     

Voice range in superior laryngealnerve paresis and paralysis

Evaluation of Physiologic Frequency Range (PFR) and Musical FrequencyRange (MRP) of Phonation was performed on 56 adults (singers and nonsingers) presenting with superior laryngeal nerve (SLN) paresis or paralysis confirmed by laryngeal electromyography. The most common etiology was neuritis (69.7%), followed by iatrogenic and unlcnown causes,each accounting for 10.2 % of cases, and finally trauma (8.9%). Both female and male singers with SLN paresis or paralysis had significantly higher PFR and MPR than nonsingers. Female classical singers presented PFR and MPR of up to 10 semitones (ST) higher than nonclassical singers and nonsingers. The lowest PFR and musical ranges were found in patients with SLN paresis associated with recurrent laryngeal nerve paresis or paralysis. The authors suggest that voice range measurement is a useful parameter for analyzing the effects of SLN paresis or paralysis on voice and that it may also assist in measuring outcome following voice therapy.     

Drugs and vocal function

Relatively little literature exists documenting the effects of pharmacological agents upon the voice. Our understanding of this subject is facilitated through review of the few studies that have been performed, as well as through understanding of the principles of action of drugs in various classes. Such study provides a reasonable basis for understanding and predicting the effects of drugs on the voice.     

Voice problems and risk factors among aerobics instructors

Fifty female and four male aerobics instructors completed a questionnairepertaining 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.     

The perceptual nature of vocal register change

This study focuses on the perceptual nature of chest and falsetto registers as a function of various production tokens and methods of perceptual evaluation. Fifteen target tones, ranging from G#3 to A#4, were sung by a male and a female subject in the context of ascending and descending sequences on the vowels /a/ and /i/. Register transitions were elicited by setting strict constraints on production. Segments of 1-s duration were extracted from the target notes, digitized, and acoustically analyzed. These excerpts were presented to ten trained listeners in four different perceptual tasks. Identification and discrimination tasks yielded nearly identical results, suggesting that the primary registers are perceived as distinct entities. The marked change from chest to falsetto as well as the locus of the transition between these registers did not vary systematically as a function of production token or perceptual task. Mean register shift-point frequencies of the male and female subjects were perceived at 320 Hz and 353 Hz, respectively. Multidimensional scaling and hierarchical clustering analyses were utilized to capture the dimensionality and the internal structure of perceptual data sets derived from the pair-wise similarity ratings. Optimal spatial representation of these data required no more than two orthogonal dimensions, with the quality attribute represented by the dominant dimension. The representation of pitch differences was reflected only in the internal ordering of the stimuli within registers, but did not affect the perceptual discontinuity between registers.     

An investigation of the third formant of /a/ in prepubertal children

The third formant (F₃) of /a/ recorded from 209 healthy children (104 male and 105 female; ages 3 to 12 years) and 40 adults (20 men and 20 women) was studied by spectral analysis. Contrary to the traditional concept, the results of this study showed that there is significant difference in voice F₃ of /a/ between male and female children. This difference was found to begin to develop at the age of 3 years and became substantial by the age of 6 years. In this study, the value of F₃ obtained from female children at the age of 6 years was unexpectedly higher than that from the male children at the same age, which indicates that there is a difference in timbre in small children of both sexes.