Changes In Fundamental Frequency Research Articles

Changes in Vocal Fundamental Frequency at the Segmental Level

In addition to cycle-by-cycle (jitter) and long-term (intonation contour and declination) changes, vocal fundamental frequency (Fo) is known to vary during moments of production of individual phones. This study explored the relationship between intra-oral pressure and Fo during the production of the English voiced fricatives (v), (z), (o), and (3). Target words were embedded in a carrier phrase spoken with three different patterns of sentence stress. Fo changed at a mean rate of -3.59 Hz/cmH2O and -7.96 Hz/cmH2O in men and women, respectively. No significant difference was observed among the different fricatives nor among the several stress patterns. A significant sex effect, not observed in a prior related study, was eliminated by conversion of the Fo data to semitones. The observed magnitudes of the ratios of Fo change to pressure change are consistent with several earlier studies that explored the effect of passive transglottal pressure changes on Fo. The present findings imply that, although Fo regulation is involved in the generation of different intonation contours, the laryngeal system is not compensated to maintain Fo in the face of the transitory changes in vocal-tract aerodynamics that accompany voiced fricative production.

An overview of changes in fundamental frequency associated with cortical insult

Abstract Recent acoustic analyses of fundamental frequency contours of both lef hemisphere damaged aphasic patients and right-hemisphere damaged non-aphasic patients have provided new data to further our understanding of brain and language mechanisms. The literature, however, is complex and even, in certain aspects, somewhat contradictory. This article attempts to assess the present ‘state-of-the-art’ of such studies, in order to provide a framework for directing future research.

Speech characteristics as indicators of depressive illness.

Measures of the rate of change of voice fundamental frequency, fundamental frequency variability, reading and counting times, and different measures of pause time were compared in 28 depressed patients and 13 healthy controls. The fundamental frequency variables were lower in the depressed group, and the pauses between the interviewer's questions and the patient's answers were longer. The remaining speech variables, including the summed duration of interdigit pauses in counting from 1 to 10 (speech pause time), did not differ between the groups.

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.

発声時声門下圧信号の周波数分析による声門下共鳴の検討

Subglottal pressure signals during phonation were evaluated by linear prediction analysis in fifteen normal adults.The first subglottal resonance frequencies, exhibited individual variation, ranging from 420 Hz to 720 Hz. The change in fundamental frequency affected resonance spectra, also suggesting individual variation of subglottal resonance. Moreover, spectrum differences among vowels indicated coupling between the supraglottal and subglottal systems during the closed phase.

The role of the right hemisphere in the production of linguistic stress

Recent research has proposed a general prosodic disturbance associated with right hemisphere damage (RHD), one encompassing both affective and linguistic functions. The present study attempted to explore whether the ability to produce linguistic prosody was impaired in this patient population. Productions of phonemic stress tokens (e.g., Re'dcoat vs. red coa't) as well as examples of contrastive stress, or sentential emphasis (e.g., Sam hated the movie), were elicited from eight male speakers with unilateral right hemisphere CVAs and seven male control subjects. Two types of analyses were conducted on these utterances. Acoustic analysis focused on the correlates associated with word stress, namely changes in amplitude, duration, and fundamental frequency. The perceptual saliency of emerging cues to stress was also examined by presentation of test tokens to phonetically trained listeners for identification of stress placement. The patients as a group produced fewer acoustic cues to stress compared to the normal subjects, but no statistical differences were found between groups for either stress at the phrase level or at the sentence level. In the perceptual analysis, stress produced by the patient group was judged to be less salient than that for the normal group, although a high degree of variability was evident in both populations. The data suggest a spared processing mechanism for linguistic prosody in RHD speakers, thus mitigating against the view of a general dysprosody tied to RHD.

Relationship between changes in voice pitch and loudness

Summary Changes in mean fundamental frequency accompanying changes in loudness of phonation are analyzed in 9 professional singers, 9 nonsingers, and 10 male and 10 female patients suffering from vocal functional dysfunction. The subjects read discursive texts with noise in earphones, and some also at voluntarily varied vocal loudness. The healthy subjects phonated as softly and as loudly as possible at various fundamental frequencies throughout their pitch ranges, and the resulting mean phonetograms are compared. Mean pitch was found to increase by about half-semitones per decibel sound level. Grossly, the subject groups gave similar results, although the singers changed voice pitch more than the nonsingers. The voice pitch changes may be explained as passive results of changes of subglottal pressure required for the sound level variation.

Bending‐beam model of vocal‐fold vibration

Recent theoretical developments have shown that a model based on the theory of bending beams is the best predictor of the fundamental frequencies of young children's speech [Bickley, Proc. 11th Int. Congr. Phon. Sci. (1987)]. For children of age 3 years and younger, the values predicted by a spring‐mass model are too low, and the values of a vibrating‐string model are too high. In the current study, the effect of growth of the vocal‐fold structure on fundamental frequency is analyzed. The vocal‐fold structure grows nonuniformly; for example, a 1‐year‐old's vocal folds are approximately one‐fifth as long as an adult's folds but only 10% thinner. The bending‐beam model is an improvement over other models because it reflects the structure of the vocal folds and the attachments of the vocal‐fold tissue to the arytenoid and thyroid cartilages, characteristics previously ignored. The fundamental frequency of the new model depends on both the beamlike characteristics of the vocal folds and the springiness of the structure. Changes in fundamental frequency are predicted from the model as a function of age.

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.

Twitch response in the canine vocalis muscle.

The twitch response of the canine vocalis muscle was investigated through a series of experiments conducted in vitro. Samples of vocalis muscle were dissected and prepared from canine larynges a few minutes before death and kept in Krebs solution at a temperature of 37 +/- 1 degrees C and pH of 7.4 +/- 0.05. Field stimulation with parallel-plate silver electrodes was applied to study the twitch response of muscle samples. The peak tension and time course of isometric contraction of isolated muscle samples were measured electronically with a Cambridge Technology Dual Servo System (ergometer). Contraction time and 50% relaxation time of this muscle were measured for seven samples at various levels of strain. It was found that contraction time ranged between 22 and 32 ms and 50% relaxation time ranged between 17 and 37 ms. Results indicate that the vocalis muscle is a fast muscle capable of performing rapid maneuvers in support of changes in fundamental frequency.

Aerodynamic and myoelastic contributions to tracheoesophageal voice production.

Five laryngectomized, tracheoesophageal (TE) speakers completed a series of phonatory tasks developed to assess (a) aerodynamic and acoustic properties of TE voice and (b) aerodynamic and myoelastic contributions to the mediation of fundamental frequency change. These TE speakers' voices were characterized by increased trans-source airflow rates, comparable source driving pressures, and decreased airway resistances in comparison with standard esophageal speakers. TE speakers were capable of adjusting their voicing sources on a myoelastic basis to influence Fo change. This result, coupled with findings that confirm aerodynamic contributions to TE phonation, are interpreted to suggest that TE voice production should be regarded as an aerodynamic-myoelastic event. Findings are integrated with existing data to highlight fundamental differences among TE, esophageal, and normal voice production.

Why is the formant frequency difference limen asymmetric?

Flanagan [J. Acoust. Soc. Am. 27, 613–617 (1955)] observed asymmetries in formant frequency difference limen in the perception of some synthesized vowel‐like sounds and attributed those asymmetries to the proximity of neighboring formants. This hypothesis about the origin of the asymmetries in the perception of differences in vowel formant position is tangible and is widely accepted. The perceptual experiments of Hermansky and Jaykin [J. Acoust. Soc. Am. Suppl. 1 80, S18 (1986)] showed that the asymmetries in formant frequency difference limen can be reversed by small changes in fundamental frequency in the experiment. This observation questions the contribution of neighboring formants as a factor in the perception of small differences in formant position. Results of experiments in the perception of synthetic vowel‐like sounds will be presented. They suggest that the formant distribution was not a major factor contributing to perceptual asymmetries in Flanagan's experiment. The role of formant structure in vowel perception is discussed.

Role of diaphragmatic activity during singing: a study of transdiaphragmatic pressures

Esophageal and gastric pressures during singing are measured in four male professional singers performing singing tasks requiring rapid changes of subglottal pressure. Evidence for a consistent use of the diaphragm is found in all subjects. Some subjects punctually activate the diaphragm when there is a need for a rapid decrease of subglottal pressure, such as when singing a falling octave interval, when shifting from a loud to a soft note, to save air during a /p/ explosion, and in performing a trillo involving a repeated switching between glottal adduction and abduction. The first three cases were observed in the beginning of the phrase, presumably over the period that the pressure generated by the passive expiratory recoil forces of the breathing system was higher than the intended subglottal pressure. In addition to this, one subject exhibited a diaphragmatic tonus throughout the entire phrase. The phonatory relevance of a diaphragmatic activity was evaluated in a subsequent experiment. The transdiaphragmatic pressure was displayed on an oscilloscope screen as a visual feedback signal for singers and nonsingers, who performed various phonatory tasks with and without voluntary coactivation of the diaphragm. In most subjects this activity tended to increase the glottal closed/open ratio as well as the amplitude of the glottogram (i.e., the transglottal volume velocity wave-form as determined by inverse filtering). These changes suggest that diaphragmatic coactivation tends to affect phonation. Also, it tended to reduce the formant frequency variability under conditions of changing fundamental frequency suggesting a better stabilization of the vocal tract.

On the interaction of tone and intonation in Mandarin Chinese

Intonation in many languages, including English, is realized most effectively by changes in fundamental frequency. It is important to investigate whether this relation holds true in a tone language, where F0 variation may affect lexical meaning. This paper reports the interaction of tones and intonation in a tone language, Mandarin Chinese, and calculates the effects of various intonation patterns as well as focus structures. The result is implemented and tested in a Chinese text‐to‐speech system. In general, the interrogative pattern in Mandarin Chinese is characterized by a high reference line and a high boundary tone at the end of a sentence. However, the resulting tone shape is not always rising as a result of the lexical tones. Focus is realized mainly by increasing the pitch range, but the exact implementation is complicated by some local tonal effects such as target shift. This paper will also explain the interaction of catathesis (pitch lowering triggered by specific tonal context) and focus in the direction of prosodic structure.

The transmission of prosodic information via an electrotactile speechreading aid.

Variations in voice fundamental frequency were extracted from naturally produced speech samples and transmitted to an electrocutaneous display consisting of 10 electrodes arranged in a linear array along the forearm. Changes in fundamental frequency were encoded as changes in stimulus location. Speechreading performance, with and without the electrocutaneous aid, was examined for both sentence and connected discourse materials with one profoundly hearing-impaired listener and one normally hearing listener whose hearing was masked. After 20 hours of speechreading training in connected discourse tracking procedure, both subjects showed higher tracking rates and faster learning rates with the aid than without the aid. Results from closed-set sentence-identification tests showed that patterns of intonation, stress, and phrase structure, which are not easily speechread, are readily available with the aid.

Voice source effects of diaphragmatic activity in singing

The transdiaphragmatic pressure was displayed on an oscilloscope screen as a visual feedback signal for singers and non-singers who performed various phonatory tasks with and without voluntary co-activation of the diaphragm. The diaphragmatic co-activation tended to increase the amplitude of the flow glottogram, i.e., the transglottal air volume velocity waveform as determined by inverse filtering and also tended to reduce the formant frequency variability under conditions of changing fundamental frequency.

Pitch change as a cue to syllabification

It has been observed that fundamental frequency changes during the vowel segment of a synthesised monosyllabic word such as “yes” may cause the word to be perceived as bisyllabic. This phenomenon occurs even though the intensity and spectrum of the vowel remain constant. Experiments have shown that the bisyllabic percept is brought about by a non-final fall–rise intonation contour, provided that the durations of the segment containing the rise and the segment following this are sufficiently long. The duration of the segment containing the fall appears to be of no consequence.

Pacinian corpuscles and polyharmonic vibrations

Psychophysical and physiological experiments using low amplitude, high‐frequency vibrations which selectively activate Pacinian corpuscle mechano‐receptors have been employed to address the question: Can the vibrotactile system distinguish between pure and polyharmonic sinusoidal stimuli applied to the glabrous skin in the presence of concomitant changes in fundamental frequency and amplitude? Human subjects are presented with stimulus pairs in which a pure tone is paired with a tone having a significant second harmonic component. The fundamental frequency and amplitude of each member of the pair are varied independently so they typically differ in peak‐to‐peak amplitude and frequency composition as well as harmonic content. In addition, different phase relations between the fundamental and harmonic of the diharmonic tone are used. The subjects are asked to identify which member of the pair is diharmonic. Responses of Pacinian corpuscles to the same tone pairs are recorded from afferent fibers in the forelimb of the cat, using both on‐center and off‐center stimulation. The eventual goal is to collect similar data in primates in order to be able to describe the neural basis for the discrimination ability observed in the psychophysical tests.

Some observations on segment duration and its interaction with the fundamental frequency contour in Swedish

In a previous study [B. Lyberg, J. Phonet. 9, 97–103 (1981)] quite strong evidence was found in favor of a relationship between segment duration and fundamental frequency change in certain positions of an utterance such as the phrase final position. The speech material used in the study was built up of Swedish words containing only phonologically long vowel segments. In the present investigation this relationship was studied once more but this time for both phonologically long and short vowel segments in order to elucidate the interaction between the signaling of the quantity distinction and the fundamental frequency contour. The results show that the segment duration of the stressed vowel in monosyllabic words in phrase final position is positively correlated with the fundamental frequency change of the terminal fall when the vowel is followed by a voiced consonant for both phonologically short and long vowels. When the vowel is followed by a voiceless consonant the terminal fall seems to be compressed in the time dimension.

Voice fundamental frequency changes associated with clinically identified stress state

An upward shift in voice fundamental frequency (pitch) has been reported in human subjects undergoing a wide variety of experiences that are assumed to be stressful [J. K. Darby, Ed., Speech Evaluation in Psychiatry (1981)]. Precise measurement of pitch rise as a function of ongoing physiological stress level was obtained from 35 patients with panic disorders and 18 controls undergoing a biochemical challenge (infusion of sodium lactate) that is known reliably to elicit stress reactions from panic patients within 20 min, but not from normals. Pitch was computed from the narrow‐band harmonic spectrum of the word “five” uttered during the course of a counting task performed at 5‐min intervals during the infusion. Twenty‐one patients who panicked showed an average pitch rise of about 1 semitone in the 5‐min period before panic, and reached a maximum of 2 semitones which was significantly related to time of panic onset. Among 14 patients who did not panic, pitch showed no consistently upward trend, but did reach a maximum significantly above that of the controls. Among the controls, panic never occurred, and pitch change was negligible.