On the relation between subglottal pressure and fundamental frequency in phonation

The change in fundamental frequency with subglottal pressure in phonation is quantified on the basis of the ratio between vibrational amplitude and vocal fold length. This ratio is typically very small in stringed instruments, but becomes quite appreciable in vocal fold vibration. Tension in vocal fold tissues is, therefore, not constant over the vibratory cycle, and a dynamic tension gives rise to amplitude-frequency dependence. It is shown that the typical 2-6 Hz/cm H2O rise in fundamental frequency with subglottal pressure observed in human and canine larynges is a direct and predictable consequence of this amplitude-frequency dependence. Results are presently limited to phonation in the chest register.     

Phonatory control in male singing: A study of the effects of subglottal pressure, fundamental frequency, and mode of phonation on the voice source

This article describes experiments carried out in order to gain a deeper understanding of the mechanisms underlying variation of vocal loudness in singers. Ten singers, two of whom are famous professional opera tenor soloists, phonated at different pitches and different loudnesses. Their voice source characteristics were analyzed by inverse filtering the oral airflow signal. It was found that the main physiological variable underlying loudness variation is subglottal pressure (Ps). The voice source property determining most of the loudness variation is the amplitude of the negative peak of the differentiated flow signal, as predicted by previous research. Increases in this amplitude are achieved by (a) increasing the pulse amplitude of the flow waveform; (b) moving the moment of vocal fold contact earlier in time, closer to the center of the pulse; and (c) skewing the pulses. The last mentioned alternative seems dependent on both Ps and the ratio between the fundamental frequency and the first formant. On the average, the singers doubled Ps when they increased fundamental frequency by one octave, and a doubling of the excess Ps over threshold caused the sound pressure level (SPL) to increase by 8–9 dB for neutral phonation, less if mode of phonation was changed to pressed. A shift of mode of phonation from flow over neutral to pressed was associated with a reduction of the peak glottal permittance i.e., the ratio between peak transglottal airflow to Ps. Flow phonation had the most favorable relationship between Ps and SPL.     

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.     

The effect of fundamental frequency on the brightness dimension of timbre

The dependency of the brightness dimension of timbre on fundamental frequency (FO) was examined experimentally. Subjects compared the timbres of 24 synthetic stimuli, produced by the combination of six values of spectral centroid to obtain different values of expected brightness, and four FO's, ranging over 18 semitones. Subjects were instructed to ignore pitch differences. Dissimilarity scores were analyzed by both ANOVA and multidimensional scaling (MDS). Results show that timbres can be compared between stimuli with different FO's over the range tested, and that differences in FO affect timbre dissimilarity in two ways. First, dissimilarity scores reveal a term proportional to FO difference that shows up in the MDS solution as a dimension correlated with FO and orthogonal to other timbre dimensions. Second, FO affects systematically the timbre dimension (brightness) correlated with spectral centroid. Interestingly, both terms covaried with differences in FO rather than chroma or consonance. The first term probably corresponds to pitch. The second can be eliminated if the formula for spectral centroid is modified by introducing a corrective factor dependent on FO.     

The effect of hearing loss on the resolution of partials and fundamental frequency discrimination

The relationship between the ability to hear out partials in complex tones, discrimination of the fundamental frequency (F0) of complex tones, and frequency selectivity was examined for subjects with mild-to-moderate cochlear hearing loss. The ability to hear out partials was measured using a two-interval task. Each interval included a sinusoid followed by a complex tone; one complex contained a partial with the same frequency as the sinusoid, whereas in the other complex that partial was missing. Subjects had to indicate the interval in which the partial was present in the complex. The components in the complex were uniformly spaced on the ERB(N)-number scale. Performance was generally good for the two "edge" partials, but poorer for the inner partials. Performance for the latter improved with increasing spacing. F0 discrimination was measured for a bandpass-filtered complex tone containing low harmonics. The equivalent rectangular bandwidth (ERB) of the auditory filter was estimated using the notched-noise method for center frequencies of 0.5, 1, and 2 kHz. Significant correlations were found between the ability to hear out inner partials, F0 discrimination, and the ERB. The results support the idea that F0 discrimination of tones with low harmonics depends on the ability to resolve the harmonics.     

The biomechanics of the medialization laryngoplasty(thyroplasty type 1) in an ex vivo canine model

The biomechanics of medialization laryngoplasty are not well understood. An excised canine larynx model was used to test the effects of various sized silicon implants. The vocal fold length, position, and tension were measured. Medialization laryngoplasty did not affect vocal fold length. At the mid-membranous vocal fold, larger shims resulted in greater medialization and tension. Medialization laryngoplasty neither medialized nor stiffened the vocal process to resist lateralizing forces. We conclude that medialization laryngoplasty provides bulk and support for defects of the membranous region of the vocal fold, but does not appear to close a posterior glottal gap. The selection of a surgical procedure to treat glottal incompetence should take into account the unique biomechanical properties of the anterior (membranous vocal folds) and posterior (cartilaginous portion) glottis.     

An autocorrelation model with place dependence to account for the effect of harmonic number on fundamental frequency discrimination

Fundamental frequency (f0) difference limens (DLs) were measured as a function of f0 for sine- and random-phase harmonic complexes, bandpass filtered with 3-dB cutoff frequencies of 2.5 and 3.5 kHz (low region) or 5 and 7 kHz (high region), and presented at an average 15 dB sensation level (approximately 48 dB SPL) per component in a wideband background noise. Fundamental frequencies ranged from 50 to 300 Hz and 100 to 600 Hz in the low and high spectral regions, respectively. In each spectral region, f0 DLs improved dramatically with increasing f0 as approximately the tenth harmonic appeared in the passband. Generally, f0 DLs for complexes with similar harmonic numbers were similar in the two spectral regions. The dependence of f0 discrimination on harmonic number presents a significant challenge to autocorrelation (AC) models of pitch, in which predictions generally depend more on spectral region than harmonic number. A modification involving a "lag window"is proposed and tested, restricting the AC representation to a limited range of lags relative to each channel's characteristic frequency. This modified unitary pitch model was able to account for the dependence of f0 DLs on harmonic number, although this correct behavior was not based on peripheral harmonic resolvability.     

On the relation between the phonation threshold lung pressure and the oscillation frequency of the vocal folds

This Letter presents an extension of a previous equation for the phonation threshold pressure by Titze [I. R. Titze, J. Acoust. Soc. Am. 83, 1536-1552 (1988)]. The extended equation contains the vocal-fold oscillation frequency as an explicit factor. It is derived from the mucosal wave model of the vocal folds by considering the general case of an arbitrary time delay for the mucosal wave to travel the glottal height. The results are illustrated with a numerical example, which shows good qualitative agreement with experimental measures.     

The interrelationship of subglottic air pressure, fundamental frequency, and vocal intensity during speech

In this study we have simultaneously measured subglottic air pressure, airflow, and vocal intensity during speech in nine healthy subjects. Subglottic air pressure was measured directly by puncture of the cricothyroid membrane. The results show that the interaction between these aerodynamic properties is much more complex that previously believed. Certain trends were seen in most individuals, such as an increase in vocal intensity with increased subglottic air pressure. However, there was considerable variability in the overall aerodynamic properties between subjects and at different frequency and intensity ranges. At certain frequencies several subjects were able to generate significantly louder voices without a comparable increase in subglottic air pressure. We hypothesize that these increases in vocal efficiency are due to changes in vocal fold vibration properties. The relationship between fundamental frequency and subglottic pressure was also noted to vary depending on vocal intensity. Possible mechanisms for these behaviors are discussed.     

A preliminary study of particle velocity during phonation in an in vivo canine model

The particle velocity across the glottis was measured with simultaneous electroglottography, photoglottography, and subglottic pressure in an in vivo canine model of phonation. A constant temperature anemometer measured flow velocity at five midline anterior to posterior glottal positions. Tracheal input air flow was varied in five steps from 175 to 500 cc/s, while vocal fold approximation was achieved by constant electrical stimulation of the laryngeal nerves. For all levels of air flow, a decreasing peak velocity gradient was observed from the anterior commissure to the arytenoids. Time-varying features of the flow velocity are discussed in relation to glottal vibratory events and aerodynamics.     

The relation between composition in laser absorption region and ambient pressure

In this paper, the compositions in a laser absorption region can be determined from the experiment of laser impulse coupling. When the ambient pressure varies from 9325 to 33325Pa, the compositions are vapour and plasma; while from 35325 to 101325Pa, they are ambient air and plasma. By analysing the relation between the degree of compression and the ambient pressure, the compositions can be determined and the variation of plasma can be explained.     

The relation between composition in laser absorption region and ambient pressure

In this paper, the compositions in a laser absorption region can be determined from the experiment of laser impulse coupling. When the ambient pressure varies from 9325 to 33325Pa, the compositions are vapour and plasma; while from 35325 to 101325Pa, they are ambient air and plasma. By analysing the relation between the degree of compression and the ambient pressure, the compositions can be determined and the variation of plasma can be explained.     

On a relation between the mobility edge problem and an isotropicXY model

The critical behaviour of noninteracting electrons in a disordered solid is investigated near the mobility edge. A two component “spin glass” order parameter which—in contrast to previous work—is gauge invariant, is introduced and it is shown by renormalization group arguments that the system can be mapped to anXY model. Using recent results on the jump in the spin wave stiffness of a two dimensionalXY model an universal exact minimum conductivity value \(\sigma _M = \frac{{e^2 }}{\hbar }\frac{1}{{\pi ^2 }}\) is found which agrees well with numerical predictions. An extrapolation of the proportionality between conductivity and spin wave stiffness to other spatial dimensions yields Wegner's power law, with an exponent related to theXY model.     

The influence of alcoholic intoxication on the fundamental frequency of female and male speakers

This study investigates long-term features and utterance contours of fundamental frequency (f0) derived from the German Alcohol Language Corpus. The corpus comprises read, spontaneous, and command&control speech uttered by 148 speakers of both genders and various age groups when sober and intoxicated. f0 median, f0 range, and f0 contours are analyzed for intoxication and interactions with gender and age. Contours are compared both directly (root mean squared error, statistical correlation, or the Euclidean distance in the spectral space of the contour) and by parameterization of the contour using discrete cosine transform and the first and second moment of the lower contour spectrum. Results partly confirm earlier findings, i.e., f0 average and range are mostly raised with intoxication, and also suggest that the majority of speakers do not follow a general trend, but show idiosyncratic alterations to f0. f0 contours differ significantly with intoxication, but a more detailed analysis could not assign these changes to specific general form changes like decline or curvature. The results suggest that it is not possible to predict intoxication from f0 in a single model across different speakers. Instead a speaker-dependent model to account for the individual speaker behavior is proposed.     

The direct and indirect roles of fundamental frequency in vowel perception

Several experiments have found that changing the intrinsic f0 of a vowel can have an effect on perceived vowel quality. It has been suggested that these shifts may occur because f0 is involved in the specification of vowel quality in the same way as the formant frequencies. Another possibility is that f0 affects vowel quality indirectly, by changing a listener's assumptions about characteristics of a speaker who is likely to have uttered the vowel. In the experiment outlined here, participants were asked to listen to vowels differing in terms of f0 and their formant frequencies and report vowel quality and the apparent speaker's gender and size on a trial-by-trial basis. The results presented here suggest that f0 affects vowel quality mainly indirectly via its effects on the apparent-speaker characteristics; however, f0 may also have some residual direct effects on vowel quality. Furthermore, the formant frequencies were also found to have significant indirect effects on vowel quality by way of their strong influence on the apparent speaker.