Voice outcome in patients treated for laryngeal cancer: efficacy of voice rehabilitation.

OBJECTIVE: To investigate the efficacy of voice rehabilitation regarding acoustically measured voice quality as well as self-perceived function after radiotherapy for laryngeal cancer. STUDY DESIGN: Prospective intervention study. METHODS: Twenty male patients irradiated for laryngeal cancer participated in the study. Voice recordings and self-assessment of voice function (hoarseness, vocal fatigue, and vocal loudness) were made one and 6 months after completion of radiotherapy. The recordings were analyzed with the program Praat. Ten of the patients received 10 sessions of structured voice rehabilitations between the recordings and 10 worked as a control group. RESULTS: Jitter and shimmer improved for both groups. Harmonics-to-noise-ratio and maximum phonation time improved for the patients who received voice rehabilitation while it deteriorated for the control group. The self-assessment questions about vocal fatigue and vocal loudness showed improvement for both groups while hoarseness showed no change. CONCLUSION: General improvement was seen for both the study group and the control group. Despite the lack of statistical significant difference, there are trends where greater improvement in perturbation and self-assessment measures are noted in the study group. The results suggest positive effects of voice rehabilitation in both voice quality and self-perceived function.

Mapping emotions into acoustic space: the role of voice production.

Research on the vocal expression of emotion has long since used a "fishing expedition" approach to find acoustic markers for emotion categories and dimensions. Although partially successful, the underlying mechanisms have not yet been elucidated. To illustrate that this research can profit from considering the underlying voice production mechanism, we specifically analyzed short affect bursts (sustained/a/vowels produced by 10 professional actors for five emotions) according to physiological variations in phonation (using acoustic parameters derived from the acoustic signal and the inverse filter estimated voice source waveform). Results show significant emotion main effects for 11 of 12 parameters. Subsequent principal components analysis revealed three components that explain acoustic variations due to emotion, including "tension," "perturbation," and "voicing frequency." These results suggest that future work may benefit from theory-guided development of parameters to assess differences in physiological voice production mechanisms in the vocal expression of different emotions.

Musical theater and opera singing--why so different? A study of subglottal pressure, voice source, and formant frequency characteristics.

The considerable voice timbre differences between musical theater (MT) and western operatic singers are analyzed with respect to voice source and formant frequencies in five representatives of each singer group. Audio, subglottal pressure (P(sub)), and electroglottograph (EGG) signals were recorded while the subjects sang a sequence of [pae:] syllables starting at maximal vocal loudness and then gradually decreasing vocal loudness. The task was performed at each of two fundamental frequencies (F(0)), approximately one octave apart. Ten equally spaced P(sub) values were then selected for each F(0). The subsequent vowels were analyzed in terms of flow glottograms derived by inverse filtering the audio signal, which also yielded formant frequency data. Period time (T(0)), peak-to-peak pulse amplitude (U(p-t-p)), and maximum flow declination rate (MFDR) were measured from the flow glottograms while closed quotient Q(closed) (T(cl)/T(0)) was determined in combination with the differentiated EGG signal. Also the relationship between the first and the second harmonic in the spectrum (H(1)-H(2)), the amplitude quotient (AQ), that is, the ratio between U(p-t-p) and MFDR, and normalized AQ, that is, AQ normalized with respect to period time was calculated as well as the sound pressure level. The results showed that both the MT and the opera singers varied their P(sub) systematically, approximately doubling P(sub) for a doubling of F(0). For a given value of P(sub), the MT singers produced higher values of MFDR, U(p-t-p), and Q(closed), and lower values of H(1)-H(2), indicating a weaker fundamental. Further, the MT singers showed higher formant frequencies and did not show the opera singers' characteristic clustering of F(3), F(4), and F(5).

Comparison of two inverse filtering methods in parameterization of the glottal closing phase characteristics in different phonation types.

SUMMARY: Inverse filtering (IF) is a common method used to estimate the source of voiced speech, the glottal flow. This investigation aims to compare two IF methods: one manual and the other semiautomatic. Glottal flows were estimated from speech pressure waveforms of six female and seven male subjects producing sustained vole /a/ in breathy, normal, and pressed phonation. The closing phase characteristics of the glottal pulse were parameterized using two time-based parameters: the closing quotient (C1Q) and the normalized amplitude quotient (NAQ). The information given by these two parameters indicates a strong correlation between the two IF methods. The results are encouraging in showing that the parameterization of the voice source in different speech sounds can be performed independently of the technique used for inverse filtering.

Subglottal pressure and normalized amplitude quotient variation in classically trained baritone singers.

The subglottal pressure (Ps) and voice source characteristics of five professional baritone singers have been analyzed and the normalized amplitude quotient (NAQ), defined as the ratio between peak-to-peak pulse amplitude and the negative peak of the differentiated flow glottogram and normalized with respect to the period time, was used as an estimate of glottal adduction. The relationship between Ps and NAQ has been investigated in female subjects in two earlier studies. One of these revealed NAQ differences between both singing styles and phonation modes, and the other, based on register differences in female musical theatre singers, showed that NAQ differed between registers for the same Ps value. These studies thus suggest that NAQ and its variation with Ps represent a useful parameter in the analysis of voice source characteristics. The present study aims at increasing our knowledge of the NAQ parameter further by finding out how it varies with pitch and Ps in professional classically trained baritone singers, singing at high and low pitch (278 Hz and 139 Hz, respectively). Ten equally spaced Ps values were selected from three takes of the syllable [pae:], initiated at maximum vocal loudness and repeated with a continuously decreasing vocal loudness. The vowel sounds following the selected Ps peaks were inverse filtered. Data on peak-to-peak pulse amplitude, maximum flow declination rate and NAQ are presented.

An amplitude quotient based method to analyze changes in the shape of the glottal pulse in the regulation of vocal intensity.

This study presents an approach to visualizing intensity regulation in speech. The method expresses a voice sample in a two-dimensional space using amplitude-domain values extracted from the glottal flow estimated by inverse filtering. The two-dimensional presentation is obtained by expressing a time-domain measure of the glottal pulse, the amplitude quotient (AQ), as a function of the negative peak amplitude of the flow derivative (d(peak)). The regulation of vocal intensity was analyzed with the proposed method from voices varying from extremely soft to very loud with a SPL range of approximately 55 dB. When vocal intensity was increased, the speech samples first showed a rapidly decreasing trend as expressed on the proposed AQ-d(peak) graph. When intensity was further raised, the location of the samples converged toward a horizontal line, the asymptote of a hypothetical hyperbola. This behavior of the AQ-d(peak) graph indicates that the intensity regulation strategy changes from laryngeal to respiratory mechanisms and the method chosen makes it possible to quantify how control mechanisms underlying the regulation of vocal intensity change gradually between the two means. The proposed presentation constitutes an easy-to-implement method to visualize the function of voice production in intensity regulation because the only information needed is the glottal flow wave form estimated by inverse filtering the acoustic speech pressure signal.

Throaty voice quality: subglottal pressure, voice source, and formant characteristics.

"Throaty" voice quality has been regarded by voice pedagogues as undesired and even harmful. This study attempts to identify acoustic and physiological correlates of this quality. One male and one female subject read a text habitually and with a throaty voice quality. Oral pressure during p-occlusion was measured as an estimate of subglottal pressure. Long-term average spectrum analysis described the average spectrum characteristics. Sixteen syllables, perceptually evaluated with regard to throaty quality by five experts, were selected for analysis. Formant frequencies and voice source characteristics were measured by means of inverse filtering, and the vocal tract shape of the throaty and normal versions of the vowels [a,u,i,ae] of the male subject were recorded by magnetic resonance imaging. From this material, area functions were derived and their resonance frequencies were determined. The throaty versions of these four vowels all showed a pharynx that was narrower than in the habitually produced versions. To test the relevance of formant frequencies to perceived throaty quality, experts rated degree of throatiness in synthetic vowel samples, in which the measured formant frequency values of the subject were used. The main acoustic correlates of throatiness seemed to be an increase of F1, a decrease of F4, and in front vowels a decrease of F2, which presumably results from a narrowing of the pharynx. In the male subject, voice source parameters suggested a more hyperfunctional voice in throaty samples.

Voice source differences between registers in female musical theater singers.

Musical theater singing typically requires women to use two vocal registers. Our investigation considered voice source and subglottal pressure P(s) characteristics of the speech pressure signal recorded for a sequence of /pae/ syllables sung at constant pitch and decreasing vocal loudness in each register by seven female musical theater singers. Ten equally spaced P(s) values were selected, and the relationships between P(s) and several parameters were examined; closed-quotient (Q(closed)), peak-to-peak pulse amplitude (U(p-t-p)), amplitude of the negative peak of the differentiated flow glottogram, ie, the maximum flow declination rate (MFDR), and the normalized amplitude quotient (NAQ) [U(p-t-p)/(T0*MFDR)], where T0 is the fundamental period. P(s) was typically slightly higher in chest than in head register. As P(s) influences the measured glottogram parameters, these were also compared at an approximately identical P(s) of 11 cm H2O. Results showed that for typical tokens, MFDR and Q(closed) were significantly greater, whereas U(p-t-p) and therefore NAQ were significantly lower in chest than in head.

Velum behavior in professional classic operatic singing.

The velopharyngeal opening (VPO) is analyzed in 17 professional operatic singers, 3 high sopranos, 3 sopranos, 2 mezzo-sopranos, 3 tenors, 2 baritones, 2 bass-baritones, and 2 basses singing the vowels [a, i, u] at middle degree of vocal loudness at different pitches throughout their pitch range. Three methods were used for detection of a VPO. One was nasofiberscopy, which revealed VPO of various shapes in several singers. Another method was recording nasal and oral airflow by means of a divided flow mask. These measurements showed a nasal DC airflow at least at some pitches in a majority of the singers. A third method was a comparison of the level of the fundamental in the nasal and oral airflow signals; this level difference was less than 15 dB in cases where a nasal DC airflow was observed. Values less than 15 dB were observed in some cases, thus suggesting the presence of a VPO. The tokens produced by the singers were assessed by an expert panel with respect to nasal quality of the vowel timbre; no correlation was found between rated nasal quality and the presence of a VPO.