Howard B. Rothman

Noise and tremor in the perception of vocal aging in males.

OBJECTIVE/HYPOTHESIS To specify a set of acoustic cues for vocal aging and to establish their perceptual relevance. STUDY DESIGN Perceptual testing. METHODS To identify the acoustic and perceptual correlates of the aging voice, voice quality [in conjunction with speaking rate and fundamental frequency (F(0))] was systematically manipulated using resynthesis to determine its effect on perceived age. Ten young male voices were resynthesized using two levels of noise (random modulation of F(0) contour) and two levels of tremor (constant modulation of F(0) contour with a low-amplitude wave) under a speaking-rate manipulation (an increase in speaking rate that is common to older male voices). These materials were submitted to 40 naive listeners in an age-estimation task. Two sets of comparison materials were also included for evaluation: unmanipulated samples from a 150 voice database of young, middle-aged, and older voices and disordered voice samples representing natural manifestations of the voice qualities of interest. RESULTS Speaking rate, highest degree of tremor, and highest degree of noise all shifted, in an additive manner, the mean perceived age of the young male voices by a maximum of 12 years on average; individual voices were observed being shifted by a generation. Fundamental frequency manipulations had no significant effect on perceived age. CONCLUSIONS Voice quality (both tremor and noise) and speaking rate are all perceptually relevant cues of age in male voices.

A comparison of speech using artificial larynx and tracheoesophageal puncture with valve in the same speaker

Postlnryngectomy speech rehabilitation more frequently includes surgical‐prosthetic methods since the introduction of a low morbidity tracheoesophageal puncture technique und a one‐way alrflow valve. This study compares speech using an artificial larynx and, in one case, esophageal speech with speech using a tracheoesophageal puncture and valve in the same speaker. Using nonprofessional listeners, speech was rated for intelligibility and preference. Voice spectrograms were employed for measurement of rate, fundamental frequency, and intensity. While no statistically significant differences were found in mean fundamental frequency or intensity, the rate of post‐tracheoesophageal speech was considerably faster. In addition, when individual speakers are compared with themselves, post‐tracheoesophageal speech is significantly more intelligible and preferred by nalve listeners. We conclude that using the tracheoesophageal puncture with valve should be strongly considered in total laryngectomy patients whose present mode of communication is unsatisfactory.

Acoustical Comparison Between Samples of Good and Poor Vibrato in Singers

The purpose of this research was to analyze samples of frequency vibrato taken from recordings of eight different singers, which were classified as examples of good or poor singing. The samples were analyzed by a software package, which makes use of the linear prediction coding (LPC) method to determine the time varying rate and extent of the frequency vibrato wave. Four parameters, which relate to the periodicity of the samples, were extracted from the time varying rate and extent and investigated in order to verify or reject the hypothesis that the best vibrato samples were the most symmetric ones. Ten samples per singer were analyzed, 5 good and 5 poor, for a total of 80 samples. The results show that the samples judged as good were the most periodic ones.

Effects of Vocal Training on Respiratory Kinematics during Singing Tasks

This longitudinal study determined the effects of vocal training (VT) on respiratory kinematics and muscle activity during singing tasks. Four voice students, 3 females and 1 male, were recorded during singing tasks once a semester for 3 consecutive semesters. Respiratory kinematic measures included lung volume, rib cage (RCE) and abdominal excursions (ABE). Surface electromyographic measures included burst duration (BD) and peak amplitude (PA) of the pectoralis major, rectus abdominis and external oblique muscles. Descriptive statistics revealed that RCE and ABE increased from the 1st to the 2nd semester, but decreased from the 2nd to the 3rd semester of VT. Overall, mean BD decreased from the 1st to the 2nd semester and increased from the 2nd to the 3rd semester. Mean PA increased from the 1st to the 2nd semester and decreased from the 2nd to the 3rd semester of VT. RCE and muscle force generation of the above muscles increased as the demand level and the length of the phonatory tasks increased. Interpretation of the results suggests that the respiratory system is highly responsive to VT, after only 3 semesters of training.

Judgments of voice quality and preference: Acoustic interpretations

Summary Previous studies have shown that trained listeners are highly reliable in making perceptual judgments of several parameters of normal and pathologic voices. This study investigated objective measures of acoustic characteristics of high and low preference voices as determined by previous perceptual study. Four acoustic parameters were measured including harmonics-to-noise ratio, autocorrelation function, average jitter, and the standard deviation of the fundamental frequency. Useful correlations between perceptual and measured results were identified. Normal voices differ from pathologic voices in terms of the acoustic-perceptual relationships.

Acoustic variability in vibrato and its perceptual significance

Summary Historically, studies of vocal vibrato have concentrated on pulse rate as being a primary factor in determining whether a given vocal movement is a good or bad vibrato or a tremolo or wobble. More recently, investigators have been studying the extent of frequency variation and amplitude variation around their respective means in order to determine their influence on the perception of vibrato. The present study is an additional attempt to understand the three parameters comprising vibrato, their interrelationship, and their relationship to perception. Samples of sustained sung tones were obtained primarily from recordings. The samples were digitized using a 16-bit A/D converter at a sampling frequency of 10 kHz. Each digitized sample was converted to a useful format for marking purposes in order to derive information on vibrato pulse rate, the mean frequency of the tone, the semitone deviation around the mean, percent frequency deviation and percent amplitude variation around the mean amplitude. Data presentation utilizes representative samples of good vibrato, tremolo and wobble and describes differences in waveforms which may impact on perception.

Comparing historical and contemporary opera singers with historical and contemporary Jewish cantors

This study is an attempt to ascertain if singers from different traditions and milieus follow similar aesthetic trends regardless of training and/or background. Cantors who sang the Jewish synagogue liturgy during the Golden Age of cantorial singing prior to World War II came from Eastern and Central Europe. For the most part, they were not trained in the classical Western opera tradition. They received training from choir leaders and other cantors and the training was primarily in the modes of synagogue chant. Cantors today receive the same kinds of training that opera singers receive, often from the same teachers. Four groups of singers, consisting of four singers in each group, were utilized in this study. The four groups are: historical opera singers, contemporary opera singers, historical cantors, and contemporary cantors. The historical opera singer recordings date from as early as 1909 to as late as 1939. It was not possible to determine the dates of the historical cantor recordings. However, the four cantors chosen for this group were active only to the 1940s. Contemporary samples were taken from CDs and/or live recordings and all the singers from the contemporary groups are either still active or were active in the 1960s through the 1980s and all of them are considered to be premier-level singers in their respective areas. The variables analyzed were: vibrato pulse rate, frequency variation of the vibrato pulse above and below the mean sustained sung frequency in percent, the mean amplitude variation of the amplitude vibrato pulse above and below the mean sustained amplitude in percent and the fast Fourier transform (FFT) power spectrum of the sustained samples. Results indicate that most of the significant differences were found between eras and not between groups within a time period.

A mathematical model of singers’ vibrato based on waveform analysis

There is controversy regarding the best model to synthesize vibrato. Some authors include random components in their models while others suggest a deterministic model. Also, the vibrato waveform has not been studied in detail, that is, no measures have been made as to symmetry of the waveform, and parameters different from wave frequency and amplitude have not been studied. Therefore, research was undertaken to thoroughly analyze the vibrato waveform from selected singers in order to obtain a model based on the vibrato parameters. Seven premier‐level singers were selected and three samples per singer were used. These samples were analyzed through the MMSV (Mathematical Model of Singers’ Vibrato) software, which was specifically designed for vibrato analysis. The results obtained for all the samples were analyzed and compared, and a model fitting all of them was proposed. This model was compared against a sinusoidal model and the real wave for two different samples by the use of an error measure and visually, and it was verified that the model reproduced the variations of the real vibrato wave and significantly reduced the error measure of the sinusoidal model. The results show that a deterministic model fits all the samples under study.

Shifting perceptions of age in voice

A series of experiments have been carried out in order to identify the acoustical and perceptual correlates of the aging voice. The initial phase of the program was to identify those voice parameters which signal a person’s age; the second phase was to systematically shift these parameters in order to determine if a parallel change in perceived age would occur. This second study focused on temporal characteristics related to voice. In this instance, standard speech samples for 16 males aged 70–90 years were contrasted with those of 14 males aged 20–33 years. The features studied included the following: (1) sentence duration, (2) word duration, (3) diphthong duration, (4) consonant‐vowel ratios, (5) number of pauses and (6) pause duration. Significant differences were found for all relationships. Subsequently, a preliminary study was carried out where the voices were synthesized and the temporal parameters for the two groups shifted toward each other. The preliminary data suggest that such modifications lead especially to the idea that the voices of older individuals actually were those of younger men.

Perceptual (aural) and spectrographic investigation of speaker homogeneity

In order to investigate the perceptual and spectrographic homogeneity of speakers, 28 (14 pairs) talkers recorded an extended prose passage on two occasions, one week apart. Twelve talkers were chosen as six pairs on the basis of their having been confused with each other due to the similarity of their voices. A tape was prepared for the presentation of two randomized 2‐sec speech segments for each pair of talkers. Listeners made aural/perceptual judgments of same or different for the following conditions: (1) same/contemporary (i.e., one talker recorded at the same time); (2) same/noncontemporary (i.e., one talker recorded one week apart); (3) different (i.e., paired talkers). Preliminary analysis of the data indicate the following: (1) 96% correct identifications were obtained for the same talker paired with a contemporary speech segment; (2) 44% correct identifications were obtained when comparing the same talker with a noncontemporary speech sample; (3) 87% correct identifications were obtained when c...