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Biomedical subjects

Erkki Vilkman

Publications and source records attributed to Erkki Vilkman.

18 recordsLinked to original sources
PubMed2006

Acoustic measures and self-reports of vocal fatigue by female teachers.

This study investigated the relation of symptoms of vocal fatigue to acoustic variables reflecting type of voice production and the effects of vocal loading. Seventy-nine female primary school teachers volunteered as subjects. Before and after a working day, (1) a 1-minute text reading sample was recorded at habitual loudness and loudly (as in large classroom), (2) a prolonged phonation on [a:] was recorded at habitual speaking pitch and loudness, and (3) a questionnaire about voice quality, ease, or difficulty of phonation and tiredness of throat was completed. The samples were analyzed for average fundamental frequency (F0), sound pressure level (SPL), and phonation type reflecting alpha ratio (SPL [1-5 kHz]-SPL [50 Hz-1 kHz]). The vowel samples were additionally analyzed for perturbation (jitter and shimmer). After a working day, F0, SPL, and alpha ratio were higher, jitter and shimmer values were lower, and more tiredness of throat was reported. The average levels of the acoustic parameters did not correlate with the symptoms. Increase in jitter and mean F0 in loud reading correlated with tiredness of throat. The results seem to suggest that, at least among experienced vocal professionals, voice production type had little relevance from the point of view of vocal fatigue reported. Differences in the acoustic parameters after a vocally loading working day mainly seem to reflect increased muscle activity as a consequence of vocal loading.

Adult↗
PubMed2006

Changes in objective acoustic measurements and subjective voice complaints in call center customer-service advisors during one working day.

SUMMARY: The aim of this study was to investigate how different acoustic parameters, extracted both from speech pressure waveforms and glottal flows, can be used in measuring vocal loading in modern working environments and how these parameters reflect the possible changes in the vocal function during a working day. In addition, correlations between objective acoustic parameters and subjective voice symptoms were addressed. The subjects were 24 female and 8 male customer-service advisors, who mainly use telephone during their working hours. Speech samples were recorded from continuous speech four times during a working day and voice symptom questionnaires were completed simultaneously. Among the various objective parameters, only F0 resulted in a statistically significant increase for both genders. No correlations between the changes in objective and subjective parameters appeared. However, the results encourage researchers within the field of occupational voice use to apply versatile measurement techniques in studying occupational voice loading.

Adult↗
PubMed2006

Occupational voice complaints and objective acoustic measurements-do they correlate?

To enable the development of appropriate diagnostics and treatment for occupational voice disorders, this study addresses connections between subjective voice complaints and objective observations. The subjects of this study were 24 female customer advisors, who mainly use the telephone during their working hours. During one working day, at four different times, speech samples covering 20 minutes of telephone conversation by the customer service advisors (CSAs) were recorded. In addition, the CSAs filled in a questionnaire (visual analogue scale) concerning their voice problems. To represent the vocal symptoms three variables were used: vocal fatigue, hoarseness and a general sum-variable. A 5-minute sample was taken from recordings for further analyses. This included fundamental frequency, sound pressure level, alpha ratio (the ratio between the spectral energy below and above 1000 Hz) and number of vocal fold vibrations. In the objective acoustic measurements, it was found that fundamental frequency (F0) rose significantly during the working day. Also the self-reported voice symptoms increased significantly during the working day. However, correlations between vocal symptoms and acoustic measures were not found.

Adult↗
PubMed2005

Automatic speaking valve in speech rehabilitation for laryngectomized patients.

For speech rehabilitation after total laryngectomy, the Provox FreeHands Heat and Moisture Exchanger (FreeHands HME; Atos Medical AB, Hörby, Sweden) was compared with the Provox Heat and Moisture Exchanger (HME), and the patients' Health-Related Quality of Life (HRQoL) was assessed. A review of the English literature was performed considering automatic speaking valves. The study design was a cohort study. Fourteen laryngectomized male patients who had used the HME successfully before receiving the FreeHands HME entered the study. An ENT specialist and a speech pathologist examined these patients. Data concerning voicing, breathing, skin adhesion, voice and speech quality, and HRQoL were collected by a structured questionnaire. Voice recordings were performed for evaluation of the quality of the voice. A computer-aided search of the MED-LINE database was conducted, supplemented by hand searches of key journals. Twelve patients had used the FreeHands HME on special social occasions and reported three main reasons why FreeHands HME was unsuitable for continuous use: heavier breathing, more difficult speaking, and worse subjective quality of voice. With HME, phonation time tended to be longer and the softest phonation softer ( P =0.034). The loudest phonation was louder with FreeHands HME ( P =0.015). Patients' HRQoL assessed by the 15D profile was similar to that of the age- and sex-matched male Finnish general population (patients 0.877, population 0.884). A review of the literature showed few works dealing with automatic speaking valves. The FreeHands HME is a useful additional device in a selected group of laryngectomized patients. Total laryngectomy did not lower patients' HRQoL notably.

Adult↗
PubMed2005

Voice symptoms of call-centre customer service advisers experienced during a work-day and effects of a short vocal training course.

Occupational voice users often suffer from voice symptoms to varying extents. The first goal of this study was to find out how telephone customer service advisers experience voice symptoms at different moments of the working day. The second goal was to investigate the effects of a short vocal training course arranged for telephone workers. The results indicate that although the subjects did not suffer from severe voice problems, the short vocal training course significantly reduced some of the vocal symptoms they had experienced. The results suggest that systematic consultation and training for occupational voice users in the field of occupational voice care would be advantageous.

Adult↗
PubMed2004

Estimating perceived phonatory pressedness in singing from flow glottograms.

The normalized amplitude quotient (NAQ), defined as the ratio between the peak-to-peak amplitude of the flow pulse and the negative peak amplitude of the differentiated flow glottogram and normalized with respect to period time, has been shown to be related to glottal adduction. Glottal adduction, in turn, affects mode of phonation and hence perceived phonatory pressedness. The relationship between NAQ and perceived phonatory pressedness was analyzed in a material collected from a professional female singer and singing teacher who sang a triad pattern in breathy, flow, neutral, and pressed phonation in three different loudness conditions (soft, middle, loud). In addition, she also sang the same triad pattern in four different styles of singing, classical, pop, jazz, and blues, in the same three loudness conditions. A panel of experts rated the degree of perceived phonatory press along visual analogue scales. Comparing the obtained mean rated pressedness ratings with the mean NAQ values for the various triads showed that about 73% of the variation in perceived pressedness could be accounted for by variations of NAQ.

Acoustics↗
PubMed2003

Automatic pre-segmentation of running speech improves the robustness of several acoustic voice measures.

In order to study vocal loading, we developed a speech analysis environment for continuous speech. The objective was to build a robust system capable of handling large amounts of data while minimizing the amount of user-intervention required. The current version of the system can analyze up to five-minute recordings of speech at a time. Through a semiautomatic process it will classify a speech signal into segments of silence, voiced speech and unvoiced speech. Parameters extracted from the input signal include fundamental frequency, sound pressure level, alpha-ratio and speech segment information such as the ratio of speech to silence. This paper presents results from the performance evaluation of the system, which shows that the analysis environment is able to perform robust and consistent measurements of continuous speech.

Algorithms↗
PubMed2002

Pitch-synchronous changes in the anterior cricothyroid space during singing.

Pitch-synchronous changes in the anterior cricothyroid (CT) space were registered with ultrasonography (USG) for ten healthy subjects (5 males, 5 females) during the production of musical fifths throughout the whole voice range. One of the males and one of the females were trained amateur singers, the other subjects were choir singers. The average decrease in CT space per a musical fifth was 1.3-2.4 mm for the males and 1.0-1.8 mm for the females; the average decrease was smaller in the middle of the pitch range for both genders. The results suggest that (1) USG can be used for detection of pitch-synchronous changes in the CT space; (2) these changes are dependent on pitch range; and (3) more trained singers tend to have somewhat smaller changes than less trained subjects at certain frequencies. The results seem to indicate that F0 control mechanism varies according to pitch range and register, and possibly according to individual structure and vocal technique related differences.

Adult↗
PubMed2002

Voice changes during work: subjective complaints and objective measurements for female primary and secondary schoolteachers.

The purpose of this investigation was to study voice changes during a working day. The subjects consisted of 33 female primary and secondary schoolteachers who recorded their first and last lessons during one school day. The subjects were studied both as one group and two subgroups (those with many and those with few voice complaints). Estimates of fundamental frequency (F0), sound pressure level (SPL), the standard deviations of these values (F0 SD; SPL SD) and F0 time (vibration time of vocal folds) were made. The most obvious change due to loading was the rise of F0 that was 9.7 Hz between the first and last lesson (P = 0.00). F0 increased more (12.8. Hz, P = 0.006) in the subgroup with few complaints.

Female↗
PubMed2002

Normalized amplitude quotient for parametrization of the glottal flow.

Normalized amplitude quotient (NAQ) is presented as a method to parametrize the glottal closing phase using two amplitude-domain measurements from waveforms estimated by inverse filtering. In this technique, the ratio between the amplitude of the ac flow and the negative peak amplitude of the flow derivative is first computed using the concept of equivalent rectangular pulse, a hypothetical signal located at the instant of the main excitation of the vocal tract. This ratio is then normalized with respect to the length of the fundamental period. Comparison between NAQ and its counterpart among the conventional time-domain parameters, the closing quotient, shows that the proposed parameter is more robust against distortion such as measurement noise that make the extraction of conventional time-based parameters of the glottal flow problematic. Experiments with breathy, normal, and pressed vowels indicate that NAQ is also able to separate the type of phonation effectively.

Adult↗
PubMedDate not supplied

Dynamic extremes of voice in the light of time domain parameters extracted from the amplitude features of glottal flow and its derivative.

In the first part of the study, the subjects (4 females, 4 males) produced sustained breathy, normal and pressed types of phonation. The maximum AC flow (f(ac)) and the negative peak amplitude (d(min)) of the first derivative of the glottal flow were extracted from glottal volume velocity waveforms estimated by inverse filtering. The ratio between f(ac) and d(min) (amplitude quotient, AQ), which gives an estimate of the closing time of the glottal flow, and its normalised version (NAQ) were computed. The NAQ values correlated strongly with the closing quotient of glottal flow. In the second part of the study, the aim was to investigate the dynamic extremes of the human voice in terms of F(0), SPL, f(ac), d(min), AQ and NAQ as well as the intraoral pressure (p) used for subglottal pressure estimation. Eleven normal subjects (5 females, 6 males) participated in this experiment. The subjects started with the production of soft phonation (approximately 55 dB at 40 cm) and increased their vocal intensity at 5-dB steps up to the level of 105 dB. At the analysis stage, the voice samples were divided into three categories: soft (<70 dB), normal (70-90 dB) and loud (>90 dB). In soft and normal phonation, intensity change was correlated with changes in the shape of the glottal flow waveform, whereas the loud voice samples showed a large increase in F(0) and p values. At the loudest extreme, d(min) approached its maximum and AQ its minimum values and NAQ started to rise. In terms of the NAQ values of stressed syllables, the type of phonation was breathy in the soft intensity category, whereas in the normal and loud intensity categories it was within the range of the pressed type of phonation of sustained phonation samples.

Adult↗
PubMedDate not supplied

Changes in teachers' speech during a working day with and without electric sound amplification.

An increase in fundamental frequency (F(0)) and in sound pressure level (SPL) has been reported both after vocal loading tests and after a teacher's working day. This increase has been found to be greater among teachers with fewer voice complaints. The present study investigated speech changes during a teacher's working day (a) in ordinary conditions and (b) when using electric sound amplification while teaching. Five Icelandic teachers (mean age 51 years) volunteered as subjects. Classroom speech was recorded with a portable DAT recorder and a head-mounted microphone first in ordinary conditions, and the next week while using electrical sound amplification. Recordings were made during the first and the last lesson of the hardest working day of the week. F(0) and SPL were analyzed. The subjects' comments were gathered by questionnaire. An increase in F(0) and SPL was found during the working day in both teaching conditions but the change was larger and for F(0) statistically significant when amplification was used. All 5 teachers reported less tiredness of the vocal mechanism when using amplification. The results support the suggestion that a vocal loading-related increase in F(0) and SPL is not merely a sign of vocal fatigue but may even reflect an adequate adaptation to loading. Situational factors cannot be ignored, however.

Adult↗
PubMedDate not supplied

Loading-related subjective symptoms during a vocal loading test with special reference to gender and some ergonomic factors.

Vocal loading-related subjective symptoms were studied in a day-long vocal loading test. The voices of 40 female and 40 male voluntary young students were loaded by having them read aloud a novel for five times 45 min. The subjective symptoms that occurred during the vocal loading session were reported by filling in a questionnaire after each session. The responses loaded on five factors in a factor analysis: (1) 'central fatigue'; (2) 'symptoms of the neck, shoulders and back'; (3) 'drying in the mouth and throat'; (4) 'symptoms of the throat'; (5) 'symptoms of the voice'. The exposure groups (5 females and 5 males per cell) consisted of eight combinations of the following factors: (1) low (25 +/- 5%) or high (65 +/- 5%) relative humidity of ambient air; (2) low [<65 dB(SPL)] or high [>65 dB(SPL)] speech output level of vocal loading; (3) sitting or standing posture during vocal loading. The lowest mean score for symptoms pooled over the test were found in 'symptoms of the neck, shoulders and back' and the highest mean symptom score in 'drying in the mouth and throat' and 'symptoms of the throat'. Most symptoms were at their minimum during the first loading session and increased statistically significantly to a peak mean value after three or five vocal loading sessions. Statistically significant differences in the mean level between the gender or exposure groups emerged for 'central fatigue' (humidity had clear effects) and 'symptoms of the neck, shoulders and back' (gender, humidity and posture had clear effects). In these cases, females had more symptoms than males; the low-humidity group had more symptoms than the high-humidity group, and the standing subjects had more symptoms than the sitting subjects.

Adolescent↗
PubMedDate not supplied

Experiences of a short vocal training course for call-centre customer service advisors.

It is commonly known that occupational voice users suffer from voice symptoms to varying extents. The purpose of this study was to find out the effects of a short (2-day) vocal training course on professional speakers' voice. The subjects were 38 female and 10 male customer advisors, who mainly use the telephone during their working hours at a call centre. The findings showed that although the subjects did not suffer from severe voice problems, they reported that the short vocal training course had an effect of some of the vocal symptoms they had experienced. More than 50% of the females and males reported a decrease in the feeling of mucus and the consequent need to clear the throat, and diminished worsening of their voice. Over 60% thought that voice training had improved their vocal habits and none reported a negative influence of the course on their voice. Females also reported a reduction of vocal fatigue. The subjects were further asked to respond to 23 statements on how they experienced the voice training in general. The statements 'I learned things that I didn't know about the use of voice in general' and 'I got useful and important knowledge concerning my work' were highly assessed by both females and males. The results suggest that even a short vocal training course might affect positively the self-reported well-being of persons working in a vocally loading occupation. However, to find out the long-term effects of a short training course, a follow-up study would need to be carried out.

Adult↗
PubMedDate not supplied

Occupational safety and health aspects of voice and speech professions.

A well-functioning voice is an essential tool for one third of the labour force. Vocal demands vary to a great extent between the different voice and speech professions. In professions with heavy vocal loading (e.g. school and kindergarten teachers), occupational voice disorders threatening working ability are common. Vocal loading is a combination of prolonged voice use and additional loading factors (e.g. background noise, acoustics, air quality) affecting the fundamental frequency, type and loudness of phonation or the vibratory characteristics of the vocal folds as well as the external frame of the larynx. The prevention and treatment of occupational voice disorders calls for improved occupational safety and health (OSH) arrangements for voice and speech professionals. On the basis of epidemiological and acoustic-physiological research, the presence of risk to vocal health can be substantiated. From the point of view of the physical load on the vocal apparatus, loading-related physiological changes (adaptation) may play a role in the occupational risk. Environmental factors affect vocal loading changes. In teaching professions, the working environment is shared with children, who benefit from amendments of OSH legislation concerning their teachers.

Adolescent↗
PubMedDate not supplied

Immediate effects of 'voice massage' treatment on the speaking voice of healthy subjects.

'Voice massage' (VM) treatment includes manipulation of muscles related to speech production and voice and breathing exercises. This study investigated the effects of VM in 10 healthy subjects (5 females, 5 males). They recorded repetitions of the word 'paappa' at normal loudness and as softly as possible and read a text sample before and after 1-hour (1) VM treatment, (2) fast walking, (3) sitting in a library and (4) lying on a bed. Subglottic pressure was estimated from oral pressure during [p]. Transglottal flow and glottal resistance were measured. Voice production was studied with electroglottography. Fundamental frequency, sound pressure level (SPL) and alpha ratio [(SPL of the range 1-5 kHz) - (SPL of the range 50 Hz-1 kHz)] were calculated from text samples, which were also evaluated by 7 voice experts. A questionnaire was used to record subjects' sensations. Changes after lying and sitting suggest lowered effort in phonatory muscles, while after fast walking effort seemed to increase. After VM no significant changes were observed in voice parameters or perceptual quality, but ease of phonation and reduced tension in the neck, shoulders and back were reported. The effects of VM may be partly psychological, partly related to a search of phonatory balance.

Adult↗