Thomas Shipp

Vocal Loudness and Effort in Continuous Speech

The direct‐magnitude‐estimation scaling technique was used to investigate listener perception of vocal loudness and vocal effort of a continuous speech sample. Three experimental conditions were developed that represented (1) normal changes in loudness and effort, (2) intensity held constant and effort varied, and (3) intensity varied and effort constant. The speech samples were judged by 20 listeners on the magnitudes of loudness and of the amount of effort used by the speaker during phonation. Exponents of the loudness and effort functions (1.12 and 0.57, respectively) suggest that vocal loudness and effort are different percepts of the listener. An examination of the acoustic stimuli suggests that a systematic increase in stimulus bandwidth with an increase in vocal intensity may be related to judgments of both loudness and effort.

Vocal frequency and vertical larynx positioning by singers and nonsingers

Measurements were taken from lateral still photographs of the vertical larynx position of four professional singers and four nonsingers. Subjects sustained phonation at seven discrete intervals between 90 and 350 Hz. Nonsingers generally positioned their larynx upward with increased voice frequency and tended to maintain a level at or above the larynx physiologic rest position throughout their vocal range. Singers usually maintained a laryngeal position below the physiologic rest level throughout their vocal frequency range.Subject Classification: 70.20; 75.70.

Comparative measures of vocal tremor and vocal vibrato

Summary Acoustic analyses were carried out on vocal vibrato produced by nine opera singers and vocal tremor accompanying the sustained phonation of patients with the following diagnoses: Parkinsons disease, amyotrophic lateral sclerosis, spinal muscular atrophy, essential tremor, and adductor spastic dysphonia. While vocal tremor on average had a faster oscillatory rate and greater amplitude extent when compared to vocal vibrato, only the cycle to cycle measures of shimmer and jitter differed significantly between these groups. However, these differences existed even when the effect of the oscillation was removed. These data are consistent with the hypothesis that vocal vibrato in singers and vocal tremor in patients may be part of the same continuum.

Vertical laryngeal position: Research findings and application for singers

Summary Research on vertical laryngeal position (VLP) is sparse, but shows that singers with classic vocal training maintain a VLP at or below a resting level. Untrained singers typically position their larynx higher as pitch increases, usually to a level well above the rest position. It has been shown that the larynx moves vertically by muscular forces and not by aerodynamic pressures. It appears that maintaining a low VLP during singing results in (1) facilitating a vocal fold vibratory pattern that produces substantial energy in the higher portion of the spectrum, (2) opening of supraglottal resonators, (3) easing of register transitions, and (4) reducing the magnitude of vocal fold closure forces.

Acoustic properties of straight tone, vibrato, trill, and trillo

Summary Recordings were made of four internationally acclaimed early music singers (two women, two men) as they sustained phonation at target frequencies while producing the vocal ornaments straight tone, vibrato, trill, and trillo. Recordings were analyzed for the presence and amount of fundamental frequency oscillation and the frequency location of the vocal ornament performed with respect to the target tone. Results showed great variability between singers in all measured parameters.

Predicting postoperative voice characteristics of spastic dysphonia patients.

Current treatment of spastic dysphonia may involve unilateral RLN section preceded by a temporary chemical paralysis of one RLN as a diagnostic test. This study compared the immediate postchemical paralysis and postsurgical paralysis voice and speech qualities of 33 spastic dysphonic patients using perceptual, acoustic, and temporal measurements and found that following section of the RLN, there was a decrease in overpressure and aperiodicity, an increase in vocal range, and a reduction of breathiness. Vocal tremor and speech rate were variably affected. It appears that chemical paralysis of the RLN is a fairly accurate means of previewing the postsurgical voice.

Postoperative and Follow-up Studies of Spastic Dysphonia Patients Treated by Recurrent Laryngeal Nerve Section

Long-term results of surgical treatment of spastic dysphonia by RLN section are evaluated by means of perceptual psychophysical scaling and by the patients themselves. It is found that a significant reduction in spastic dysphonia symptoms occurs as a result of surgery, and that these results are maintained after long-term follow-up in the majority of patients. These experimental observations are in agreement with the subjective assessment of postsurgical communication by the patients involved in the study.

METHOD AND CONTROL OF LARYNGEAL EMG ELECTRODE PLACEMENT IN MAN

An EMG procedure has been devised for sampling the intrinsic laryngeal muscles during phonation. Problems regarding subject medication, selection, and construction of electrodes, and method and verification of electrode placement are discussed.

Comparison of Subglottal Air Pressures Associated with /p/ and /b/

Intraoral air‐pressure differences between voiced‐voiceless cognates have been attributed by most investigators to a transglottic pressure drop associated with voicing. This assumes pressures below the glottis of essentially the same magnitude during the production of these sounds. The present study tests this assumption. Airflow and subglottal air pressure were recorded as 10 adult males spoke syllables containing /p/ and /b/ in the intervocalic position. Each uttered the syllables stressing the initial vowel and again stressing the final vowel. The airflow trace was used to provide reference points for air‐pressure measurement. First, pressure values were measured at a point of no air flow prior to consonant release lip opening and second, the pressure point that corresponded with maximum airflow after release. Analysis of these values showed no significant difference between the pressures at the two points of measurement nor between measures obtained for /p/ and /b/. Differences were found related only...

Trillo Rates Exhibited by Professional Early Music Singers

Summary Trillo rates of nine professional early music singers were assessed from recordings made as they varied their repetition rate between slow and fast at the 25, 50, and 75% levels of their concert pitch ranges. Continuous trilli at all pitch levels formed two distinct clusters: slow trillo rates ranged from 2.0 to 6.9 Hz and fast extended from 7.5 to 12.4 Hz. Trillo rates did not differ as a function of singers voice type, gender, age, experience, or location in the voice range.