Fundamental Frequency Distribution Research Articles

Clinical Characteristics and Voice Analysis of Patients With Mutational Dysphonia: Clinical Significance of Diplophonia and Closed Quotients

The aim of this study was to investigate the acoustic and electroglottographic characteristics of patients with mutational dysphonia before and after voice therapy. The clinical records of 15 patients with mutational dysphonia were reviewed, and their voice recordings were analyzed with the help of the Lx Speech Studio program (Laryngograph Ltd, London, UK). After voice therapy combined with the manual compression method, the subjects' voices lowered in pitch and improved in quality. In addition, we classified the mutational dysphonia into four categories according to the presence of diplophonia and closed quotients. The most common type among the categories was characterized by a bimodal distribution of fundamental frequency (diplophonia), accompanied by a low closed quotient (falsetto voice) at high frequencies. However, the results also showed that mutational dysphonia cannot be generalized as always having a falsetto voice, as shown in other types. The effect of therapy was different for each type, and those cases with both diplophonia and a non-trained falsetto voice could be treated more readily. Consequently, the diplophonia and closed quotient, which were easily analyzed using Lx Speech Studio program, are important factors in the classification of mutational dysphonia. Identification of these characteristics may affect treatment choices, facilitate monitoring of the efficacy of therapy, and aid in estimating prognosis.

Evaluation of the affective valence of speech using pitch substructure

In order to study the relationship between emotion and intonation, a new technique is introduced for the extraction of the dominant pitches within speech utterances and the quasi-musical analysis of the multipitch structure. After the distribution of fundamental frequencies over the entire utterance has been obtained, the underlying pitch structure is determined using an unsupervised "cluster" (Gaussian mixtures) algorithm. The technique normally results in 3-6 pitch clusters per utterance that can then be evaluated in terms of their inherent dissonance, harmonic "tension", and "major or minor modality". Stronger dissonance and tension were found in utterances with negative affect, relative to utterances with positive affect. Most importantly, utterances that were evaluated as having positive or negative affect had significantly different modality values. Factor analysis showed that the measures involving multiple pitches were distinct from other acoustical measures, indicating that the pitch substructure is an independent factor contributing to the affective valence of speech prosody.

Acoustical properties of speech as indicators of depression and suicidal risk.

Acoustic properties of speech have previously been identified as possible cues to depression, and there is evidence that certain vocal parameters may be used further to objectively discriminate between depressed and suicidal speech. Studies were performed to analyze and compare the speech acoustics of separate male and female samples comprised of normal individuals and individuals carrying diagnoses of depression and high-risk, near-term suicidality. The female sample consisted of ten control subjects, 17 dysthymic patients, and 21 major depressed patients. The male sample contained 24 control subjects, 21 major depressed patients, and 22 high-risk suicidal patients. Acoustic analyses of voice fundamental frequency (Fo), amplitude modulation (AM), formants, and power distribution were performed on speech samples extracted from audio recordings collected from the sample members. Multivariate feature and discriminant analyses were performed on feature vectors representing the members of the control and disordered classes. Features derived from the formant and power spectral density measurements were found to be the best discriminators of class membership in both the male and female studies. AM features emerged as strong class discriminators of the male classes. Features describing Fo were generally ineffective discriminators in both studies. The results support theories that identify psychomotor disturbances as central elements in depression and suicidality.

Density of voicing information in purely temporal consonant identification

Speech waveforms containing purely temporal information (i.e., flat spectra and instantaneous amplitudes identical to natural speech, obtained by randomly changing the polarity of consecutive samples) contain quasiperiodic fluctuations in amplitude coincidental with voice periods. The temporal complexity of such waveforms can be reduced by half-wave rectifying the speech prior to removal of the spectral information. This study addresses the question of whether such simplification of the waveform improves the transfer of voicing information in a VCV context in normal hearing adults. The results of consonant identification experiments will be presented in which (a) the two polarities of half-wave rectification are compared to the unrectified condition (equivalent to full-wave rectification) and (b) the waveforms are low-pass filtered at the upper extreme of the fundamental frequency distribution of the speaker, prior to full-wave or half-wave rectification and removal of spectral information. Such filtering removes much of the quasi-periodicity arising from voicing in the full-wave rectified condition. [Work supported by the MRC UK.]

A voice accumulation--validation and application.

Studies of vocal behavior under natural conditions require suitable techniques for obtaining records of voice use. We describe the operation of a newly designed voice accumulator that allows registration of fundamental frequency and phonation time during a 12-hour period. The device is based on microprocessors and allows accumulation of the voice fundamental frequency within 60-600 Hz. The voice signal is picked up by a contact microphone attached to the front part of the neck. Analysis of fundamental frequency distribution and phonation time is made on a personal computer. Validation of the device shows it to provide accurate measurements of fundamental frequency, although it tends to underestimate phonation time. In a field test, the accumulator was used to analyze vocal behavior during two work-days in a group of nurses and a group of speech pathologists. Overall, the speech pathologists had a lower fundamental frequency level and higher values of phonation time than the nurses. These field results confirm the validation of the voice accumulator.

Measuring the rate of change of voice fundamental frequency in fluent speech during mental depression.

A method of measuring the rate of change of fundamental frequency has been developed in an effort to find acoustic voice parameters that could be useful in psychiatric research. A minicomputer program was used to extract seven parameters from the fundamental frequency contour of tape-recorded speech samples: (1) the average rate of change of the fundamental frequency and (2) its standard deviation, (3) the absolute rate of fundamental frequency change, (4) the total reading time, (5) the percent pause time of the total reading time, (6) the mean, and (7) the standard deviation of the fundamental frequency distribution. The method is demonstrated on (a) a material consisting of synthetic speech and (b) voice recordings of depressed patients who were examined during depression and after improvement.

Acoustic analysis of speech variables during depression and after improvement.

Speech recordings were made of 16 depressed patients during depression and after clinical improvement. The recordings were analyzed using a computer program which extracts acoustic parameters from the fundamental frequency contour of the voice. The percent pause time, the standard deviation of the voice fundamental frequency distribution, the standard deviation of the rate of change of the voice fundamental frequency and the average speed of voice change were found to correlate to the clinical state of the patient. The mean fundamental frequency, the total reading time and the average rate of change of the voice fundamental frequency did not differ between the depressed and the improved group. The acoustic measures were more strongly correlated to the clinical state of the patient as measured by global depression scores than to single depressive symptoms such as retardation or agitation.

Acoustic and perceptual analysis of vocal dysfunction

The purpose of the present study was to evaluate the usefulness of structuring perceptual voice characterizing categories by factor analysis and to provide data for a combined acoustic—perceptual evaluation of the vocal dysfunction. A set of normal and pathological voices representing various voice disorders were presented to a jury of voice clinicians who evaluated the voices on a five-point scale for each of 26 voice describing parameters. Factor analysis of the pathological subgroup of 26 voices revealed five bipolar factors accounting for 66% of the total variance. Significant correlations were found between three of these factors and acoustic data extracted from long-time average spectra, fundamental frequency distribution analysis and frequency perturbation. Also, some of the individual voice characterizing parameters correlated significantly with acoustic data.

Intonation problems of hearing-impaired Hebrew-speaking children.

Intonation of hearing-impaired Hebrew-speaking children in Israel was studied in two speech modes: spontaneous speech and reading aloud a written text. Attention was focused on statements and questions, usually considered basic types of semantic definition and (apparently) of intonation patterns. The subjects were 9–12 year-old hearing-impaired children and a control group of hearing children of the same ages. The utterances were analysed by an IBM speech training program, which enabled graphical presentation of fundamental frequency and intensity distributions. This report presents preliminary conclusions concerning Fo ranges, Fo contours (internal vs. final intonation structure), and duration problems on hearing-impaired children, and considers the possibility and value of defining and studying intonation of the hearing-impaired.

Teflon injection in 16 patients with paralytic dysphonia: perceptual and acoustic evaluations.

Sixteen patients with paralytic dysphonia were treated with Teflon injection in the paralyzed vocal fold. Trained voice pathologists rated the pre- and postinjection voices on a 5-point scale for each 11 voice characteristics. Among these, aphonia, breathiness, and hypofunction diminished significantly after injection. The perceptual evaluation was correlated with acoustic data from long-time-average spectrum analysis, fundamental frequency distribution analysis, and waveform perturbation analysis. In this acoustic assessment, systematic changes were found in the long-time-average spectra, which agreed well with the perceptual data. In 12 of 16 patients the voice was both perceptually and acoustically improved after Teflon injection.

Perceptual and acoustic correlates of abnormal voice qualities.

A set of 17 voices representing various voice disorders were presented to a jury of voice experts who rated them on a 5-point scale for each of 28 terms frequently used for describing voices. A statistical treatment of these ratings yielded 5 bipolar factors accounting for 85% of the total variance. Significant correlations were found between four of these factors and certain acoustic data extracted fron long-time-average spectra and fundamental frequency distribution analysis of the same voice sample.

Acoustic characteristics of speech produced without oral sensation.

The acoustic characteristics of continuous speech produced by an adult male talker with and without oral (nerve block) anesthesia were investigated using digital speech processing procedures. Vowel-to-consonant ratios, long-time and short-time spectra, fundamental frequency distributions, phonation-time ratios, and rate of utterances were calculated and compared for the normal and anesthetized conditions. The results showed that the speech produced without oral sensation was characterized by a reduction and shift of high-frequency energy, temporal disorganization primarily manifested as prolongation of utterance, and higher and more variable fundamental frequencies. The study also demonstrated applicability of computer techniques on general acoustic analysis of continuous speech.

Fundamental Frequency Characteristics of Young Deaf Adults During Oral Reading

A total of 18 young deaf adults read a 181-word passage, and distributional characteristics of fundamental frequency (f0) were investigated using a period-by-period f0 analysis program. The results of analysis showed significantly higher f0 means and smaller standard deviations and mid-90% range than those for normal-hearing subject. Deaf speech was characterized, furthermore, by significantly less skewness of fundamental frequency distribution. In addition, bimodality or multimodality of f0 distributions commonly observed in speech of normal-hearing subjects were also less clear in the deaf speech samples. The results indicate limited, monotonous pitch variability and almost constantly strained type of phonation in deaf speech. [This research was supported in part by Air Force Cambridge Research Laboratories, OAR, and by National Institute of Dental Research.]

Descriptions of the speech of patients with cancer of the vocal folds. I. Measures of fundamental frequency.

Speech samples of five patients with cancer of the vocal folds and five individually matched normal speakers were analyzed with respect to: (1) maximum rate of change of fundamental frequency, (2) fundamental-frequency perturbations related to specific consonants, (3) two perturbation factors, and (4) frequency distribution of fundamental frequency. It was found that most of these measures differentiated the pathological and normal speakers. The reliability and possible usefulness of each measure for detecting laryngeal cancer are discussed.

Nonlinearity of charge flow in conductor systems

Conductor systems do possess a small degree of nonlinearity on account of the nonlinear nature of all charge flow equations. Harmonic generation due to these nonlinearities has been investigated in the case of an infinitely long cylindrical wire made of copper carrying a travelling wave of current. It has been shown that the magnitude of the second harmonic current, caused by nonlinearity by the fields required to maintain a given travelling wave current distribution of fundamental frequency f on the wire, is frequency dependent, being proportional to f3/2. The magnitude of the second harmonic current is also directly proportional to the square of the magnitude of the fundamental frequency component. At a frequency of 10 000 MHz, the ratio of second harmonic component of current to the square of the magnitude of the fundamental frequency component of current is of the order 10−13 A−1. This order of magnitude though extremely small for most practical purposes can lead to spurious signal generation if the wire is surrounded by unstable plasma, since unstable plasma under certain conditions is capable of amplification. The order of magnitude of the second harmonic also suggests how far one should go in the direction of generating spectrally pure waves if they are to be propagated over conductor systems. The problem has been solved by analyzing the conductor system at the microscopic level making use of charge–kinetic equations.

Fundamental-Frequency Measures and Ratings of the Speech of Patients with Cancer of the Vocal Folds

Speech samples of five patients with laryngeal cancer involving the vocal folds and five matched normal speakers were analyzed with respect to: (1) distribution of fundamental frequency; (2) perturbations in successive glottal periods; (3) maximum rate of change of fundamental frequency; and (4) perturbations in fundamental frequency occurring during the production of specific consonants (vocal-tract constrictions). The pathological speakers exhibited a more restricted distribution of fundamental frequency than the normal speakers. However, the other measures did not appear to differentiate the two groups of speakers. The results of listening tests, in which the same speech samples were rated with respect to hoarseness, harshness, and breathiness, are also discussed.

The occurrence of auroral pulsations in the frequency range 0·01–0·1 c/s over tromso

Optical auroral pulsations in the frequency range 0·01–0·1 c/s has been studied by an automatic zenith photometer. The distribution during the night shows a pronounced peak around 02–03 MET, with almost no pulsations occurring before 22 MET (magnetic midnight). There is a peak in the distribution of fundamental frequencies at about 0·04–0·05 c/s, but no significant frequency variation during the night. The amplitude of the pulsations decreases significantly during the night. There is no detailed correlation between the optical and magnetic pulsations.

Vibrational relaxation in gases

The velocity of ultrasonic waves has been measured in a number of gases at 25°C and for values of the ratio, ultrasonic frequency/pressure, ranging from 2 x 10 5 to 2 x 10 7 c s -1 atm -1 . Dispersion, corresponding to a single vibrational relaxation process was shown by acetylene, CD 3 Br and hexafluoro-ethane; and, to a double relaxation process, by ethane. Incipient dispersion was shown by propane, ethyl chloride, ethyl fluoride and dimethyl ether. No dispersion was shown by 1.1-difluoro-ethane, n -butane, iso -butane, neo -pentane and ammonia. Correlation of these with previous results leads to the conclusion that: ( а ) For molecules with a distribution of fundamental frequencies, such that there is only a small gap between the lowest and the remaining frequencies, vibrational activation enters via the lowest mode and spreads rapidly to the other modes, giving rise to a single relaxation process involving the whole of the vibrational energy. The chief factors determining the probability of excitation of the lowest mode are its frequency and the presence or absence of hydrogen atoms in the molecule. Molecules containing two or more hydrogen atoms suffer translational-vibrational energy transfer very much more easily than other molecules. Deuterium has almost the same effect as hydrogen. ( b ) For molecules, in which there is a large gap between the lowest and the remaining fundamental frequencies, a double relaxation process occurs. The complex energy transfer probabilities involved do not fit the same quantitative functional relation with vibrational frequency as in ( a ) above. ( c ) Torsional oscillations due to hindered internal rotation behave similarly to other fundamental modes. For molecules in which there is a large gap between the torsional frequency and the other modes (e. g. ethane) a double relaxation process occurs as in ( b ). Where there is no such gap, vibrational energy enters all modes via the torsional mode as in ( a ).