Open Quotient Research Articles

Effect of superior laryngeal nerve stimulation on phonation in an in vivo canine model

We investigated the effect of variation in superior laryngeal nerve stimulation (SLNS) on vocal fold vibration. Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three SLNS frequencies (100 Hz, 130 Hz, and 160 Hz) using a constant rate of air flow. Increasing SLNS, which causes a contraction of the cricothyroid muscle, produced a marked increase in F 0, little change in Psub, an increase in the open quotient, and a decrease in the closed quotient of the glottal cycle.

Klassifizierung von Glottisdysfunktionen mit Hilfe der Elektroglottographie

The close relationship between the muscular tension at the level of the glottis and the glottal opening time, closing time, and open quotient encourages the use of these temporal measures as an aid in classifying functional dysphonias. The validity of a 'quasi-open quotient' (QOQ) derived from the electroglottogram was explored by means of a crescendo singing task at comfortable frequency. The pattern of QOQ change during the crescendo task was determined and the range of the variable measured. In normal speakers QOQ varied from 0.75 (at low vocal intensity) to 0.40 (at high intensity). In contrast, the range of QOQ values was significantly restricted in patients with hyper- and hypofunctional dysphonia. The electroglottographical curves were registered and documented by a computer system (IBM AT, Gould DASA).

A control mechanism of voice intensity in relation to expiratory and laryngeal functions

A model explanation of controlling voice intensity in relation to expiratory and laryngeal functions is reported. Using the phonatory function analyzer PS-77 (Nagashima Medical Instruments, Tokyo), a log-linear relationship between the vocal intensity I* (dB) and the mean airflow rate U(cm3/s) was obtained during a stepwise increment of intensity with a constant pitch. More precisely, a piecewise linear relationship with an S-shaped pattern was obtained in an I* vs U* display, where U*equals; 20 log (U/U0). At most, three line segments with different slopes are necessary to approximate these relationships. To examine, theoretically, the controlling mechanism of the intensity for the different slope values in I* vs U* display, a simple intermittent triangular wave was assumed as the glottal sound. Using the model waveform, the vocal intensity can be expressed by a functional relationship with the mean airflow rate U and the open quotient. Based on this functional relationship and speculation on the physiology voice production, the contribution of laryngeal control and expiratory control on vocal intensity is discussed. Results of the experiment indicate that laryngeal control is more dominant in the middle intensity region than in either of the higher or the lower intensity regions. These findings may contribute to developing an effective means of noninvasive voice assessment.

Glottographic measures of vocal fold vibration: an examination of laryngeal paralysis.

Photoglottography and electroglottography were applied to groups of patients with recurrent laryngeal nerve paralysis, superior laryngeal nerve paralysis, and combined recurrent and superior laryngeal nerve paralyses of idiopathic causes. Individual patients with resection of the vagal nerve above the origin of the superior laryngeal nerve were also studied. Open Quotient and Speed Quotient were calculated from the photoglottography signals. Speed Quotient values significantly differentiated recurrent laryngeal nerve paralysis from idiopathic paralysis and superior laryngeal nerve paralysis, as well as from normal function. Data from patients with vagal resection clearly differentiated them from patients with recurrent laryngeal nerve paralysis. The measure of Open Quotient distinguished pathological phonation from normal, but was not as useful for separation of differing lesions. Electroglottography appeared to be less useful than photoglottography. The pathophysiology underlying the observed glottographic signals is discussed.

Enhanced amplitude of the first harmonic as a correlate of voicelessness in aspirated consonants

Acoustic analysis was undertaken to test the hypothesis that information signaling voicelessness era preceding aspirated consonant may reside in spectral characteristics associated with “breathy voice” at the onset of the following vowel. The study focused upon the enhancement of the first harmonic (H1) resulting from an increase in the open quotient of the voicing source waveform. The relative amplitudes of H1 and H2 were measured in vowels in CVd syllables pairing the consonants /p,t,k,h,b,d,g/ with the vowels /i,ɑ,u,e,Λ/. The syllables were spoken by three male native speakers of English. Harmonic amplitudes were measured from DFT spectra (computed without preemphasis) of the first few pitch periods of the vowel. In general, the amplitude of H1 was greater than that of H2 for vowels following voiceless consonants; the converse was true for voiced consonants. A perceptual study using synthetic continua (varying in VOT) is being conducted; the continua differ in relative amplitude of H1 and H2. Preliminary results indicate that for some subjects an enhanced H1 may contribute to a voiceless percept: The boundary between voiced and voiceless stops was shifted to smaller VOT values for stimuli in which the amplitude of H1 was greater than that of H2 at vowel onset. [Work supported by NIH.]

The effect of laryngeal nerve stimulation on phonation: a glottographic study using an in vivo canine model.

The present investigation was designed to examine the effect of change in vocal fold mass and stiffness on vocal fold vibration. To do this, the effect of variation in superior laryngeal nerve stimulation (SLNS) and recurrent laryngeal nerve stimulation (RLNS) was studied Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three frequencies (100, 130, and 160 Hz) for SLNS and RLNS, using a constant rate of air flow. Increasing SLNS, which caused a contraction of the cricothyroid muscle, produced a marked increase in F0, little change in Psub, an increase in open quotient (OQ), and a decrease in the closed quotient (CQ) of the glottal cycle. Increasing RLNS, which caused activation of the intrinsic laryngeal muscles, produced a modest increase in F0, a marked increase in Psub, no change in the OQ, and an increase in CQ. Phase quotient (Qp), which describes the interval between opening of the lower and upper fold margins, decreased with increasing RLNS and did not change significantly with increasing SLNS. Based upon changes in F0, Psub, OQ, CQ, and Qp, SLNS provides a physiologic correlate of the tension parameter Q, and RLNS provides a physiologic correlate of the parameter Psub in the Ishizaka and Flanagan two-mass model.

Glottal inverse filtering of nasalized vowels

Linear prediction provides a means for automatically determining an inverse filter for estimating the glottal volume velocity waveform from the acoustic speech waveform. The behavior of this type of glottographic analysis is considered for nasalized vowels. The analysis is applied to non‐nasal and nasal productions that are synthesized using a transmission line model of the vocal and nasal tracts. The analysis is also applied to nasal and non‐nasal vowel productions made by a male speaker. The effect of the nasalization is to introduce extraneous ripple onto the closed phase portion of the glottal volume velocity waveform without changing the observed open quotient. This ripple results from a closely spaced resonance antiresonance pair that is not compensated by the all‐zero linear prediction inverse filter. The low level of the ripple is accounted for by the narrow frequency range over which the inverse filter is in error. [Work supported by NIH.]

Relationships between vocal quality estimates and selected acoustic/physiological variables in normally hearing and hearing‐impaired persons

The relationship between direct magnitude estimates (DME) of voice quality and ten acoustic and physiologic parameters associated with sustained vowel productions of two normally hearing and four hearing‐impaired persons were explored by collecting simultaneous high quality audio and high‐speed laryngeal film data. Analysis of the data provided the following variables associated with each subject's vowel productions: (1) harmonic‐to‐noise ratio (H/N), (2) frequency perturbation quotient (FPQ), (3) amplitude perturbation quotient (APQ), (4) pitch period (T), (5) open quotient (OQ), (6) speed quotient (SQ), (7) mean vocal‐fold velocity during glottal closing, (8) mean vocal‐fold velocity during glottal opening, (9) mean maximum glottal area during the open phase, and (10) mean glottal area during the closed phase. DMEs of each subject's voice quality were obtained from an experienced judge. Multiple regression analysis revealed that only the FPQ variable significantly predicted the DMEs of voice quality [R ...

An acoustic perceptual study of vocal fry, using synthetic stimuli

This study addressed the issue of whether the perception of vocal fry depends on waveform shape, or whether fry is perceived categorically only as a function of frequency. Voicelike stimuli were generated with a transmission-line synthesis program [Titze, Transcripts Care Prof. Voice (1983)] that can vary fundamental frequency (F0), open quotient (γ), and speed quotient (δ), while maintaining a realistic glottal shape. In Exp. I, all combinations of F0 (40, 60, 80, and 100 Hz), γ (0.1, 0.35, and 0.6), and δ (1.0, 2.5, 5.0, and 8.0) were judged by ten trained listeners, using a binary fry-no fry forced response method. The results reinforced previous conclusions that F0 is the primary determinant in the perception of vocal fry [H. Hollien, J. Phonet. 2, 125–143 (1974)] regardless of waveshape. Mean % judged as fry was 99.4%, 75.6%, 21.1%, and 2.77% at 40, 60, 80, and 100 Hz, respectively, with chance level performance (50%) predicted at about 70 Hz. Differences among γ and δ values were statistically nonsignificant. Experiment II included only stimuli of 40 and 60 Hz, each F0 containing all combinations of γ and δ values. A round-robin tournament was utilized, whereby each stimulus competed against every other stimulus for a total of 12(N2 − N) A − B comparisons. Although intrajudge reliability was high (r≈0.8), interjudge agreement was not consistently as high, yielding nonsignificant differences among γ and δ means, and suggesting that several waveshapes are perceptually plausible within acceptable F0's.

Effective aspects of profinite groups

Profinite groups are Galois groups. The effective study of infinite Galois groups was initiated by Metakides and Nerode [8] and further developed by LaRoche [5]. In this paper we study profinite groups without considering Galois extensions of fields. The Artin method of representing a finite group as a Galois group has been generalized (effectively!) by Waterhouse [14] to profinite groups. Thus, there is no loss of relevance in our approach.The fundamental notions of a co-r.e. profinite group, recursively profinite group, and the degree of a co-r.e. profinite group are defined in §1. In this section we prove that every co-r.e. profinite group can be effectively represented as an inverse limit of finite groups. The degree invariant is shown to behave very well with respect to open subgroups and quotients. The work done in this section is basic to the rest of the paper.The commutator subgroup, the Frattini subgroup, thep-Sylow subgroups, and the center of a profinite group are essential in the study of profinite groups. It is only natural to ask if these subgroups are effective. The following question exemplifies our approach to this problem: Is the center a co-r.e. profinite group? Theorem 2 provides a general method for answering this type of question negatively. Examples 3,4 and 5 are all applications of this theorem.

Parameterization of the glottal source function and glottographic waveforms

A five‐parameter representation of glottal and glottographic waveforms is proposed. Parameters consist of amplitude, period, open quotient, symmetry (speed) quotient, and an exponent of a trigonometric function that governs the sharpness of closure. A compact mathematical formula, based on a nonlinearly distorted sinusoid, is proposed for synthesis. It produces a variety of functions, ranging from idealized square, sawtooth, and sinusoidal waveshapes to more complex truncated and skewed pulses. The effects of each parameter on the waveshapes and spectral envelopes are demonstrated. Sharpness of closure determines the spectral slope, symmetry quotient is related to the amplitude of the spectral ripple, and open quotient is related to the periodicity of the ripple. Strategies for automatic picking of the parameters are suggested for analysis of glottographic waveforms.

Timbre of Kiais: Analysis and synthesis

Kiai is a name given to sudden and violent vocalizations practised by Martial Artists. An investigation to determine formant frequencies, bandwidths and source‐spectrum giope was performed on vocalizations made by five high ranking Karateka. Spectral classifications were made using adaptations of those used for infant cries [H. M. Truby and J. Lind Act, Paed. Scand. 163, 11 (1965)]. All cepstra show strong peaks regularly spaced at pitch‐period intervals. This phenomenon is usually linked with irregularities in the pitch‐pulse timing [A.M. Noll, J. Acoust. Soc. Am. 41, 293–309 (1967)]. However digital simulations using a Terminal Analog Synthesizer indicate that it is likely that these peaks are due to an opening quotient of the vocal cords which is less than 10%. This leads to a nearly flat source spectrum. The fundamental frequency range was found to be in the order of 450–500 Hz and high amplitude resonances were found up to 6000 Hz for all vocalizations studied. Physiological considerations concerning the production and perception of these screams will be discussed and shown to be consistent with claims that Kiais have a characteristic timbre, which this analysis supports. [Work supported by U. M. E. R. G.]

Quantitative measurements of vocal fold vibration. An ultra-high-speed cinematographic investigation of normal subjects (author's transl)

Vocal fold vibration of three normal male adults was quantitatively measured with the use of ultra-high-speed cinematography. The parameters measured were fundamental period, glottal area, cpen quotient, speed index, and amplitude and speed of horizontal excursion of the edge of the vocal fold. In order to investigate cycle-tc-cycle variations of vibratory pattern, mean value, range, standard deviation and coefficient of variation of twenty successive cycles were calculated for each parameter.The results are as follows: (1) The mean value of the fundamental period was 8.10, 7.63 and 8.41 msec, respectively. The coefficient of variation was 2.47, 1.97 and 3.33%. (2) Glottal area, measured in an arbitrary unit, showed a coefficient of variation of less than 9% in all the subjects. (3) Open quotient (OQ) and speed index (SI) varied from subject to subject, presumably depending on the interaction of the glottal adjustment and expiratory force. However, the standard deviation of OQ was less than 0.03, the coefficient of variation of OQ was less than 5%, and the standard deviation of SI was less than 0.1 in all the subjects. (4) The maximum amplitude of horizontal excursion was approximately from 1 to 1.5mm. The coefficient of variation was less than 3.5% in all the subjects. (5) The speed of horizontal excursion ranged from 0.4 to 0.8m/sec for opening, and from 0.2 to 0.8m/sec for closing. The coef ficient of variation was less than 8%. (6) The cycle-to-cycle variations of all the parameters in any subject presented no trend line but showed a random type of variation.

Laryngeal Vibrations: Measurements of the Glottic Wave: Part III. The Pathologic Larynx

Two reports of vibratory measurements published recently in this journal under the same title describe the vibratory cycle of the normal larynx. Part I of the study3presented a series of detailed measurements of the glottic wave under different conditions of normal voice production. Part II4demonstrated some of the unusual vibratory patterns which form the vocal response of the larynx to the demands of daily use. For these studies, a series of normal subjects were photographed with an ultra-high speed Fastax camera during controlled episodes of phonation and the films were subjected to frame by frame analysis. Selected pictures from typical scenes were enlarged for accurate measurements, and a number of new observations regarding the vibratory cycle of the normal larynx were recorded. The results were transcribed graphically in norm measures as indicated in Fig. 1. The terms Open Quotient and Speed Quotient* were employed to describe

Discussion

In the present study, we examined the relationship between various open quotients (Oqs) and phonation types, fundamental frequency (F0), and intensity by multivariate linear regression analysis (MVA) to determine which Oq best reflects vocal fold vibratory characteristics.Using high-speed digital imaging (HSDI), a sustained vowel /e/ at different phonation types, F0s, and intensities was recorded from six vocally healthy male volunteers: the types of phonation included modal, falsetto, modal breathy, and modal pressed phonations; and each phonation was performed at different F0s and intensities. Electroglottography (EGG) and sound signals were simultaneously recorded with HSDI. From the obtained data, 10 conventional Oqs (four Oqs from the glottal area function, four kymographic Oqs, and two EGG-derived Oqs) and two newly introduced Oqs (Oqedge¯+andOqedge¯) were evaluated. And, relationships between various Oqs and phonation types, F0, and intensity were evaluated by MVA.Among the various Oqs, Oqedge¯+andOqedge¯ revealed the strongest correlations with an acoustic property and could best describe changes in phonation types: Oqedge¯+ was found to be better than Oqedge¯. OqMLK, the average of five Oqs from five-line multiline kymography was a very good alternative to Oqedge¯. EGG-derived Oqs were able to differentiate between modal phonation and falsetto phonation, but it was necessary to consider the change of F0 simultaneously. MVA showed the changes in Oq values between modal and other phonation types, the degree of involvement of intensity, and no relationship between F0 and Oqs.Among Oqs evaluated in this study, Oqedge¯+andOqedge¯ were considered to best reflect the vocal fold vibratory characteristics.