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Biomedical subjects

J Sundberg

Publications and source records attributed to J Sundberg.

At least 73 records · Page 4Linked to original sources
PubMed1989

Spectral correlates of glottal voice source waveform characteristics.

The relationships between the waveform and the spectrum of the pulsating transglottal airflow during vowel phonation are analyzed in singers and nonsingers. The waveform, called the flow glottogram, is analyzed by means of inverse filtering, and the spectrum is determined either directly, by submitting the flow glottogram to spectrum analysis, or indirectly, by measuring spectral changes accompanying phonatory changes under conditions of constant vowel articulation. The peak-to-peak amplitude of the flow glottogram pulses shows a strong relationship with the amplitude of the source spectrum fundamental and varies considerably during phonation, presumably depending on the degree of glottal ab/adduction. The negative peak amplitude of the differentiated flow glottogram shows a high correlation with the sound pressure level of the vowel.

Adult↗
PubMed1988

Articulatory Fo perturbations and auditory feedback.

Singers are required to sing with a high degree of precision of fundamental frequency (Fo). Does this mean that they have learned to compensate for the change of pitch that has been described in speech during production of different vowels? Experienced choir singers sang sustained tones with a change of vowel in mid-tone. The fundamental frequency was measured, and the resulting Fo contours were evaluated with respect to Fo effects coincident with the vowel changes. The tasks were performed both with normal auditory feedback and with the auditory feedback masked by noise in headphones. The vowels (i) and (y) were found to be associated with higher Fo than other vowels. The irregularities in the Fo curves were somewhat larger in the absence of auditory feedback. This is consistent with findings during speech production. The instability in Fo, measured as the standard deviation over each tone, was also larger in the absence of feedback.

Adult↗
PubMed1988

Measuring the rate of change of voice fundamental frequency in fluent speech during mental depression.

A method of measuring the rate of change of fundamental frequency has been developed in an effort to find acoustic voice parameters that could be useful in psychiatric research. A minicomputer program was used to extract seven parameters from the fundamental frequency contour of tape-recorded speech samples: (1) the average rate of change of the fundamental frequency and (2) its standard deviation, (3) the absolute rate of fundamental frequency change, (4) the total reading time, (5) the percent pause time of the total reading time, (6) the mean, and (7) the standard deviation of the fundamental frequency distribution. The method is demonstrated on (a) a material consisting of synthetic speech and (b) voice recordings of depressed patients who were examined during depression and after improvement.

Depression↗
PubMed1988

Spectrum factors relevant to phonetogram measurement.

Phonetograms showing the sound-pressure level (SPL) in loudest and softest possible phonation are frequently used in some voice clinics as an aid for describing the status of voice function. Spectrum analysis of the vowel /a/ produced by ten females and ten males with healthy, untrained voices revealed that the fundamental was mostly the strongest spectrum partial in soft phonation while the loudest partial in loud phonation was generally an overtone. Also, the first-formant frequency was generally lower in soft than in loud phonation. Measuring SPL in dB(A) rather than in dB lowered the phonetogram contour for soft phonation, an effect increasing with decreasing fundamental frequency. SPL measurements on a group of 22 females with healthy voices showed that the vowel /a/ gave higher SPL values than other vowels in loud phonation. The effect of using dB rather the dB(A) was great but similar for all vowels in soft phonation while, in loud phonation, the effect was small, particularly for /a/. In dB, the effect of using different vowels amounts to about +/- 5 dB, approximately. Interpretation of a phonetogram in terms of voice physiology is facilitated if SPL is given in dB and if a vowel with a high first-formant frequency is used.

Adult↗
PubMed1987

Acoustic comparison of soprano solo and choir singing.

Five soprano singers were recorded while singing similar texts in both choir and solo modes of performance. A comparison of long-term-average spectra of similar passages in both modes indicates that subjects used different tactics to achieve somewhat higher concentrations of energy in the 2- to 4-kHz range when singing in the solo mode. It is likely that this effect resulted, at least in part, from a slight change of the voice source from choir to solo singing. The subjects used slightly more vibrato when singing in the solo mode.

Female↗
PubMed1987

Role of diaphragmatic activity during singing: a study of transdiaphragmatic pressures.

Esophageal and gastric pressures during singing are measured in four male professional singers performing singing tasks requiring rapid changes of subglottal pressure. Evidence for a consistent use of the diaphragm is found in all subjects. Some subjects punctually activate the diaphragm when there is a need for a rapid decrease of subglottal pressure, such as when singing a falling octave interval, when shifting from a loud to a soft note, to save air during a /p/ explosion, and in performing a trillo involving a repeated switching between glottal adduction and abduction. The first three cases were observed in the beginning of the phrase, presumably over the period that the pressure generated by the passive expiratory recoil forces of the breathing system was higher than the intended subglottal pressure. In addition to this, one subject exhibited a diaphragmatic tonus throughout the entire phrase. The phonatory relevance of a diaphragmatic activity was evaluated in a subsequent experiment. The transdiaphragmatic pressure was displayed on an oscilloscope screen as a visual feedback signal for singers and nonsingers, who performed various phonatory tasks with and without voluntary coactivation of the diaphragm. In most subjects this activity tended to increase the glottal closed/open ratio as well as the amplitude of the glottogram (i.e., the transglottal volume velocity wave-form as determined by inverse filtering). These changes suggest that diaphragmatic coactivation tends to affect phonation. Also, it tended to reduce the formant frequency variability under conditions of changing fundamental frequency suggesting a better stabilization of the vocal tract.

Adult↗
PubMed1987

From sagittal distance to area. A study of transverse, vocal tract cross-sectional area.

In speech articulation studies, data on the pharynx are scarce. Still, the pharynx is an important part of the vocal tract. The present paper reports on an attempt to use computed tomography for investigating the pharynx. Axial computed tomograms were taken at four levels in the pharynx of a male and a female subject sustaining the vowels [u:, i:, a:, oe:]. From the tomograms the lateral width and the cross-sectional area were measured and their relations to the sagittal distance from the back pharynx wall to the midline of the tongue examined and compared with previously published data. In addition, some previous results derived from plaster casts are presented showing the corresponding distance-to-area relationship in the mouth region of some male and female subjects.

Female↗
PubMed1986

Acoustic comparison of voice use in solo and choir singing.

An experiment was carried out in which eight bass/baritone singers were recorded while singing in both choral and solo modes. Together with their own voice, they heard the sound of the rest of the choir and a piano accompaniment, respectively. The recordings were analyzed in several ways, including computation of long-time-average spectra for each passage, analysis of the sound levels in the frequency ranges corresponding to the fundamental and the "singer's formant," and a comparison of the sung levels with the levels heard by the singers. Matching pairs of vowels in the two modes were inverse filtered to determine the voice source spectra and formant frequencies for comparison. Differences in both phonation and articulation between the two modes were observed. Subjects generally sang with more power in the singer's formant region in the solo mode and with more power in the fundamental region in the choral mode. Most singers used a reduced frequency distance between the third and fifth formants for increasing the power in the singer's formant range, while the difference in the fundamental was mostly a voice source effect. In a choral singing mode, subjects usually adjusted their voice levels to the levels they heard from the other singers, whereas in a solo singing mode the level sung depended much less on the level of an accompaniment.

Acoustics↗
PubMed1983

Chest wall vibrations in singers.

The chest wall vibrations generated by phonation were examined with respect to origin, amplitude, and spectrum in seven singers. The vibrations were picked up in male and female singer subjects by means of small accelerometers, which were fastened to the skin on the center of the sternum, and, for the purpose of comparison, on the thyroid cartilage and on the trachea a few cm below the larynx. Among the factors which influence the chest wall vibrations, the subglottal pressure oscillations seem to represent the most important excitation, while the mechanical shocks from the vocal fold vibrations seem secondary. Supra- and subglottal resonances seem moderately influential. The results of the investigation suggest that it is the voice source, particularly the amplitude of its fundamental, which is reflected in the chest wall vibrations. The amplitude of these vibrations seem to lie above the threshold of the Pacinian receptors for vibratory sensation as long as the fundamental frequency is below approximately 300 Hz. The amplitude of the voice source fundamental and hence the sensation of chest vibrations vary considerably as phonation is changed along the phonatory dimension which ranges from "pressed/tense/strained" through "flow" to "breathy" phonation. For this reason it seems likely that the sensation of chest vibrations can serve as a useful nonauditory and hence room-independent signal for the voluntary control of phonation.

Adult↗
PubMed1981

Localisation of atheromatosis and calcification in the carotid bifurcation. A post mortem radiographic investigation.

A radiologic investigation of atherosclerosis in 200 preparations of the carotid bifurcation including adjacent parts of the arteries indicates, as is well known, that atherosclerotic lesions are most frequent in the bifurcation and in the carotid sinus. In these parts the mechanical strain on the vessel wall is heavy. The lesions were found mainly in the dorsal vessel wall, where stasis and eddy currents produce the prerequisites for endothelial injury and intimal degeneration.

Aged↗
PubMed1980

A comparison of contact microphone and electroglottograph for the measurement of vocal fundamental frequency.

Signals from a throat contact microphone or an electroglottograph often are more suited for fundamental frequency measurements with simple analog circuits than the radiated speech signal. This report compares a contact (accelerometer) microphone placed on the neck below the cricoid cartilage and an electroglottograph for measurement of fundamental frequency in connected speech. The advantages and drawbacks of the two methods are discussed.

Humans↗
PubMed1978

Pharyngeal constrictions.

From a fiberscope, the tip of which was swung from left to right in the pharynx, cinefilm frames were obtained which showed the cross-sectional shape of pharyngeal constrictions in back vowels. This information was combined with the information offered by X-ray pictures of the same subject phonating the same vowels on a different occasion. The results agree to a reasonable extent with previously published data obtained by different techniques, and support previous hypotheses regarding distance-to-area conversion in the pharyngeal region of the vocal tract.

Humans↗
PubMed1976

Acoustic properties of the nasal tract.

Sweep frequency measurements of the transfer function of nasals and nasalized vowels have been found to show a more complex pole-zero pattern than can be predicted with a traditional model of the nasal tract which consists of two parallel tubes coupled to the oral cavities. In this paper, we put forward the hypothesis that the more complex transfer function can be explained with reference to the shunting effect of the sinus maxillares and the sinus frontales. The two maxillar sinuses are situated in the bone symmetrically on the right and left side of the nasal tract. The two frontal sinuses are situated above the nasal tract in the bone of the forehead. These cavities are acoustically coupled to the nasal tract via short channels in the bone. Direct sweep tone data on the transfer function of the nasal tract support this hypothesis.

Acoustics↗