Biomedical subjects

E Vilkman

Publications and source records attributed to E Vilkman.

At least 19 recordsLinked to original sources

PubMed2001

Effects of sound amplification on teachers' speech while teaching.

Voice problems are common among teachers. This is most likely due to the heavy vocal load of their profession. The present study investigated one possible method to decrease the vocal load. The effects of amplification on classroom speech were studied on five Icelandic teachers (three females, two males, mean age 51 years). Classroom speech was recorded with a portable DAT recorder and a head-mounted microphone, first under ordinary conditions and in the next week while using electrical sound amplification. The average fundamental frequency (F0), sound pressure level (SPL) and phonation time were measured. According to the results, amplification significantly lowered both F0 (average 8.6 Hz for the females and 11.3 Hz for the males, p = 0.002 and 0.0001, respectively) and SPL (about 1 dB for both genders, p < 0.05), while phonation time was not significantly affected. The results suggest that electric amplification is likely to reduce vocal load.

Adult↗

PubMed2001

Effects of amplified and damped auditory feedback on vocal characteristics.

This study tested two possible methods for reducing vocal load e.g. during classroom speech. Six female subjects read aloud from a text (1) under normal circumstances, (2) while hearing their own voice amplified (through headphones) and (3) with auditory feedback damped by foam plastic earplugs inserted in the outer ear canal. Fundamental frequency (F0) and sound pressure level (SPL) decreased during both amplified and damped feedback. Additionally, during amplification the relative level of F0 compared to that of the first formant diminished, likewise the alpha ratio. These changes may indicate reduced vocal fold adduction. The results suggest that both amplification and damping of auditory feedback may reduce vocal load during phonation.

Adult↗

PubMed1999

Relationship between subjective voice complaints and acoustic parameters in female teachers' voices.

The aim of the study was to identify the acoustic correlates of female teachers' subjective voice complaints by recording their voices in their working environment. The subjects made recordings during lessons (N = 10) and breaks (N = 11). The subjects were divided into 2 groups: those with few voice complaints (FC group) and those with many voice complaints (MC group). The speech sample made in the breaks was maximally sustained /a/, from which fundamental frequency (F0), jitter, and shimmer were analyzed. The classroom samples were analyzed for F0, sound pressure level (SPL), and F0 time (the active vibration time of the vocal folds). Additionally, an index for assessing voice loading is presented. The results revealed a tendency of the MC group to have higher F0 and lower SPL and perturbation values than the FC group. The index values correlated moderately with the subjective vocal complaints.

Female↗

PubMed1999

Effects of prolonged oral reading on F0, SPL, subglottal pressure and amplitude characteristics of glottal flow waveforms.

The effects of prolonged (5x45 minute) reading (vocal loading) on fundamental frequency (F0), sound pressure level (SPL), subglottal (intraroral) pressure (p), and two glottal flow waveform parameters (AC amplitude of glottal flow, f, and negative peak amplitude of differentiated flow (d) of normal female and male subjects (N = 80) were studied. Two rest (morning and noon) and three loading (two in the morning and one in the afternoon) samples were recorded and analyzed. The glottal waveforms were obtained by inverse filtering of the acoustic pressure waveforms of speaking voice samples. The analyses were based on measurement and inverse filtering of the first stressed syllable of "paappa" words repeated 3x5 times for normal, as soft as possible, and as loud as possible phonation. In normal phonation the parameter values changed statistically significantly due to loading. In many cases the values obtained in the morning samples changed after the first loading session. This is interpreted as a vocal "warming-up effect." Especially in soft phonation p, d, and f were sensitive indicators of vocal loading. In both normal and soft phonation, the SPL, p, d, and f values tended to rise due to prolonged reading in the morning and afternoon samples, indicating increased effort (normal phonation) and a rise in the phonatory threshold (soft phonation). The lunch break vocal rest ("rest effect") considerably affected the parameter values in many cases.

Adolescent↗

PubMed1999

Simultaneous videofluorographic and dual-channel electroglottographic registration of the vertical laryngeal position in various phonatory tasks.

Simultaneous tracking of the vertical laryngeal position in various phonatory tasks was performed for 2 subjects (one male, one female) using dual-channel electroglottography (EGG) and videofluorography (videofluoroscopy). The tasks included phonation on [a:] with voluntary repeated (1) heightening and (2) lowering of the laryngeal position; alternation between [a:] and phonation on (3) [b], (4) [m], and (5) the voiced bilabial fricative [beta:]; and (6) production of the corner vowels [a, i, u]. EGG and videofluorography agreed about the direction of changes in the vertical laryngeal position in most cases. Most disagreements were found in the amount of changes. Reasons for the discrepancies, including, for example, changes in the resting position of the larynx and anteroposterior movements of the cartilages, are discussed. It can be concluded that dual-channel EGG is a valuable clinical and pedagogical tool for the analysis of the vertical displacement of larynx in well-specified phonatory tasks. The method should act most reliably on separately phonated vowels. Its applicability for studying laryngeal biomechanics more wholistically, however, is limited.

Electric Stimulation↗

PubMed1999

Speech articulation after subtotal glossectomy and reconstruction with a myocutaneous flap.

Speech samples of 9 subjects (8 males, 1 female) were recorded before and 0.5-2 years after a partial glossectomy and reconstruction with a pectoralis major myocutaneous flap. A reading sample, a list of meaningful and nonsense words, and a list of sustained vowels were recorded. The speech samples were evaluated by pairs of naive listeners and using acoustic analysis of the vowel production. Each pair listened to the recordings of only one patient. Inter-rater agreement was satisfactory. The general impression of the speech outcome varied from normal to moderately impaired. The perceptually estimated impairments of speech articulation in the after/before comparisons were statistically significant. Only the first formant of the vowel /i/ (rise) and the second formant of the vowel /a/ (drop) changed significantly at the group level. There was a negative correlation (r = -0.79) between the extent of tongue resection and the drop of the second formant of the vowel /a/. The perceptual variables showed a relationship (r = 0.74-0.82) with the changes in the level of the second formant of the vowel /i/. The relationship that emerged between the perceptual estimates and the objective acoustic parameters suggests that it will be possible to develop clinically relevant test batteries for articulatory quality analysis.

Acoustics↗

PubMed1998

Parameterization of the voice source by combining spectral decay and amplitude features of the glottal flow.

A new method is presented for the parameterization of glottal volume velocity waveforms that have been estimated by inverse filtering acoustic speech pressure signals. The new technique, Parameter for Spectral and Amplitude Features of the Glottal Flow (PSA), combines two features of voice production, the AC value and the spectral decay of the glottal flow, both of which contribute to changes in vocal loudness. PSA yields a single parameter that characterizes the glottal flow in different loudness conditions. By analyzing voices of 8 speakers it was shown that the new parameter correlates strongly with the sound pressure level of speech.

Female↗

PubMed1998

Working-day effects on the spectral characteristics of teaching voice.

Ten teachers made recordings during one normal working day using a portable DAT recorder and a head-mounted microphone. In addition, the subjects filled in a questionnaire of signs of vocal fatigue. The speech samples were selected from the first and last lesson from three points representing the beginning, middle and end part of the lesson, respectively. To standardize the samples, 30 [a] vowels from stressed syllables were chosen for spectral analysis. The level of the fundamental and second formant regions (L1), the level of frequency ranges 2-5 kHz (L2) and 5-10 kHz (L5) were measured. From these measurements the parameters L1-L0, L1-L2 and L1-L5 were formed and used in the analyses as well as the energy levels below and above 1 kHz (alpha). Statistically significant changes were observed in the following parameters: the L1-L2 and L1-L5 differences, and the alpha ratio. In general, there was an increase in the energy content of the high frequency components due to vocal loading. The subjective reports revealed a statistically significant relationship with the spectral characteristics.

Adult↗

PubMed1997

The effect of postmenopause and postmenopausal HRT on measured voice values and vocal symptoms.

OBJECTIVES: To study the effect of postmenopause and postmenopausal hormone replacement therapy (HRT) on the measured fundamental frequency (F0) and sound pressure level (SPL) of sustained phonation and speaking voice samples and on subjective vocal/laryngeal symptoms. METHODS: Forty-three postmenopausal women (mean age 51.6) were divided into three groups: a group with no HRT, an estrogen group (daily oral dose of 2 mg of estradiol valerate), and an estrogen-progestin group (daily oral dose of 2 mg of 17-B-estradiol and 1 mg of northisterone acetate). Voice measurements were made before and after 1 year of treatment. Subjective symptoms were registered using a questionnaire. RESULTS: The mean F0 and SPL decreased significantly in the group with no HRT in spontaneous speech and reading samples as did SPL in the normal phonation sample. In both groups with HRT, the mean F0 decreased significantly only in the spontaneous speech sample and the decrease was smaller than in the group with no HRT. The mean SPL decrease in the estrogen group was significant in the normal phonation sample while in the estrogen-progestin group it was significant in both the normal phonation and the reading sample. The number of subjective symptoms was smallest in the estrogen group. CONCLUSIONS: The changes in the measured voice values and the subjective symptoms experienced suggest that at least the early postmenopausal years are associated with vocal changes and that HRT counteracts this phenomenon. This seems to be more pronounced with estrogen than with a combination of estrogen and progestin.

Cohort Studies↗

PubMed1997

Effects of prolonged oral reading on time-based glottal flow waveform parameters with special reference to gender differences.

The effects of prolonged (5 x 45 min) reading (loading) on time-based glottal waveform parameters of normal female and male subjects (n = 80) were studied. Two rest (morning and noon) and three loading (two in the morning and one in the afternoon) samples were recorded and analyzed. The glottal waveforms were obtained by inverse filtering of the acoustical signal using an automatic method. The following time-based parameters were analyzed from the estimated glottal flow waveform: (1) length of fundamental period (T); (2) open quotient (OQ); (3) speed quotient (SQ); (4) closing quotient (C1Q). The analysis was based on inverse filtering of the first stressed syllable of 'paappa' words produced with normal, maximally soft and maximally loud phonation. In the morning samples the loading affected only the T and OQ values of normal phonation in a statistically significant manner. In the afternoon all the quotient values changed statistically significantly in loud and normal phonation. On the basis of increased SQ and decreased C1Q values of females it is hypothesized that the female voices tended to change towards hyperfunction due to vocal loading.

Adolescent↗

PubMed1997

Loading changes in time-based parameters of glottal flow waveforms in different ergonomic conditions.

The effects of prolonged (5 x 45 min) reading in different environmental and ergonomic conditions on time-based glottal waveform parameters of normal female and male subjects (n = 80) were studied. The exposure groups (n = 5 females and males per cell) consisted of eight combinations of the following factors: (1) normal (< 65 dB) or high (> 65 dB) speech output level; (2) sitting or standing posture; (3) low (25 +/- 5%) or high (65 +/- 5%) relative humidity of ambient air. Two rest (morning and noon) and three loading (two in the morning and one in the afternoon) samples were recorded and analyzed. The glottal waveforms were obtained by inverse filtering of the acoustical signal using an automatic method. The following time based parameters were analyzed from the estimate glottal flow waveform: (1) length of fundamental period; (2) open quotient; (3) speed quotient, and (4) closing quotient. The analysis was based on inverse filtering of the first stressed syllable of 'paappa' word repeated 3 x 5 times with normal, maximally soft and maximally loud phonation. Humidity was a significant factor in several instances. The interactions between gender and the loading factors were striking.

Adolescent↗

PubMed1997

Measuring voice under teachers' working circumstances: F0 and perturbation features in maximally sustained phonation.

This study is part of a larger project, the aim of which is to develop a method for collecting voice data in working places. In this part, maximally sustained phonation was studied to assess its stability in this kind of uncontrolled circumstances. The subjects were 11 female schoolteachers. Different portions of a sustained /a/ and two consecutively produced samples were measured. The acoustic variables measured were fundamental frequency (F0), jitter and shimmer. The results showed that two consecutively produced phonations were quite similar, but the place of the sample within the sustained vowel had a very small but statistically significant effect on the values of F0 and shimmer. Jitter varied quite a lot, and could perhaps be considered to be dependent on the recording circumstances.

Female↗

PubMed1996

A physiological and acoustic study on voiced bilabial fricative/beta:/as a vocal exercise.

The voiced bilabial fricative/beta:/has been used as a vocal exercise. The present study investigated the effects of the exercise on voice production and voice source. This study compared vowel phonation on the syllable /a:p/ with the production of the exercise and vowel phonation before and immediately after the exercise. The methods were (a) dual-channel electroglottography, from which the vertical laryngeal position was derived, (b) electromyography using surface electrodes, and (c) inverse filtering of the acoustic signal to obtain an estimate of the voice source. In the production of /beta:/ as compared with vowel phonation in most of the cases, the vertical laryngeal position seemed to be higher, the muscular activity of the larynx lower, and the slope of the voice source spectrum steeper. In vowel phonation after the exercise, the muscular activity seemed to be lower in most cases, although the voice source remained unchanged. This seems to indicate improved vocal economy.

Electromyography↗

PubMed1996

External laryngeal frame function in voice production revisited: a review.

Research indicates significant contribution of extrinsic laryngeal mechanisms to voice production. This article reviews the major theories of the role of the external laryngeal factors in voice production and relevant experimental data. The review suggests that partly neglected external factors and possibly even misinterpretation of some of the recently documented individual variation in physiological data may have unnecessarily complicated the issues pertaining to the interplay between the physiological mechanisms of the larynx. The implications of contemporary findings and documentation in the modeling of the extrinsic factors are discussed and a synthesis of empirical data into two simple models of the extrinsic forces of pitch control is presented. Also suggested by the review, a basic principle, probably underlying the laryngeal control of phonation, is put forward.

Animals↗

PubMed1996

A comparison of glottal voice source quantification parameters in breathy, normal and pressed phonation of female and male speakers.

This study concerns a comparison of different quantification techniques that have been developed to parameterize a voice source that has been estimated using inverse filtering that applies no flow mask (i.e. absolute flow values are not obtained). The speech material consisted of voices of three different phonation types produced by 5 female and 5 male subjects. Quantification of the voice source was computed using three time-based quotients that were extracted from the glottal flow waveforms, two time-based parameters that were extracted from the flow and its first derivative, one amplitude-domain quotient that was defined using both the flow and its derivative, and one frequency domain parameter that was computed from the flow signal. The results showed that phonation types could be separated from each other most effectively when quantification was based on parameters that were extracted between the instant of the maximal glottal opening and the minimum peak of the flow derivative.

Female↗

PubMed1995

Vocal-fold collision mass as a differentiator between registers in the low-pitch range.

Register shift between the chest and falsetto register is generally studied in the higher-than-speaking pitch range. However, a similar difference can also be produced at speaking pitch level. The shift from breathy "falsetto" phonation to normal chest voice phonation was studied in normal female (pitch range 170-180 Hz) and male (pitch range 94-110 Hz) subjects. The phonations gliding from falsetto to normal chest voice were analyzed using iterative adaptive inverse filtering and electroglottography. Both trained and untrained, as well as female and male subjects, were able to produce an abrupt register shift from soft falsetto to soft chest register phonation. The differences between male and female speakers in the glottal flow waveforms were smaller than expected. The register shift is interpreted in terms of a "critical mass" concept of chest register phonation.

Electric Stimulation↗

PubMed1995

Effects of bandwidth on glottal airflow waveforms estimated by inverse filtering.

The aim of this research was to examine the effect of the bandwidth on parameters that are used to quantify glottal airflow waveforms that have been obtained by inverse filtering the acoustic signals. Three bandwidths (1, 2, and 4 kHz) were compared using /a/ vowels of different phonation types. Glottal waveforms were characterized using three ratios computed from the flow (open quotient, speed quotient, and closing quotient) and two parameters extracted from the differentiated flow (the amplitude of the negative peak and the return time from the negative peak to zero level). The results show that especially in pressed phonation the bandwidth should be at least 4 kHz. Distortion caused by an insufficient frequency range was most severe in the parameters extracted from the flow derivatives. Among the parameters computed from the flow signals, the closing quotient was affected most when the bandwidth was reduced.

Female↗

PubMed1995

On the effects of various vocal training methods on glottal resistance and efficiency. A preliminary report.

The glottal resistance, i.e. the ratio of subglottic pressure to glottal flow, and the laryngeal efficiency, i.e. the ratio of oral acoustic power to aerodynamic subglottal power (multiplication of subglottig pressure and glottal flow), were measured for 11 subjects (3 males) with normal voices and for 1 female patient with glottal insufficiency in the repeated production of the nonsense word /paappa/ immediately before and after 1 min of vocal exercising with /beta:, m:/ and phonation into a narrow glass tube. For the subjects with normal voices the glottal resistance decreased in most cases and the laryngeal efficiency in half of the cases due to increased glottal flow. In contrast, for the patient the glottal resistance and efficiency increased due to decreased glottal flow. The results suggest that the vocal exercises instantly affected the control of the glottal width.

Adult↗