Fred D. Minifie

Effect of Acoustic Cues in Fricatives on Perceptual Confusions in Preschool Children

Seventeen preschool children were tested to determine their ability to discriminate among the fricatives /s, z, f, v, θ, and ð/presented in consonant‐vowel (CV) and vowel‐consonant (VC) combinations with each of three vowels/ɑ, i, aɪ/. Syllable pairs were presented to the children for each possible fricative comparison, with consonant position and vowel being the same in any one pair. The stimulus tape was analyzed to determine durations of the consonants and vowels, peak amplitude of the fricatives, and center frequency and bandwidth of the resonance curves of each of the fricatives. The contribution of these acoustic cues to discrimination among the fricatives was evaluated. The voiced‐unvoiced distinction appears to be facilitated in VC syllables by the ratio of consonant duration to vowel duration. The fricatives /s/ and /z/ are set apart from the other fricatives by their high intensity, high frequency, and shorter spectrums, thus making discriminations between /s/ or /z/ and the other fricatives con...

Measurement of Vocal Fold Motion Using an Ultrasonic Doppler Velocity Monitor

A technique is described for using the ultrasonic Doppler frequency shift as a means of continuously monitoring the velocity of vocal fold motion during voice production. The basic instrumentation employed and the theoretical principles underlying the technique are discussed. The results of a series of experiments using excised animal larynges are presented to demonstrate that a characteristic laryngeal Doppler pattern is obtained during phonation and is the result of vocal fold motion. Finally, the Doppler velocity monitor is used with human subjects. Vocal fold displacement patterns derived from the Doppler signal appear to have very good agreement with previously reported displacement values using high‐speed motion‐picture films.

Ultrasonic scans of the dorsal surface of the tongue.

Echograms of the dorsal surface of the tongue in the midsagittal plane and in coronal oblique planes are presented. Comparisons are made among tongue height measurements obtained from the transverse and longitudinal echograms and from lateral head x rays. It is concluded that ultrasonic scanning can provide information on the shape of the dorsal surface of the tongue during sustained utterances and in the articulatory rest position.

Ultrasonic Measurement of Lateral Pharyngeal Wall Displacement

A technique employing diagnostic ultrasound to evaluate lateral pharyngeal wall motion during connected discourse is described. The validity and reliability of the procedure are discussed. Typical displacement patterns are shown for normal speakers and applications to cleft palate and laryngectomized speakers discussed.

Ultrasonic Observations of Coarticulation in the Pharynx

Coarticulation effects have been observed in the motion of the lateral pharyngeal wall (LPW) during speech. Pulsed ultrasound was used to measure the displacement of LPW during the trisyllables/aba/, /abi/, /iba/, /ibi/. The extent of vowel‐consonant (VC) and consonant vowel (CV) motion was different depending on the other vowel.

Effect of Matching Time on Perstimulatory Adaptation

Widely divergent amounts of perstimulatory adaptation have been reported previously, possibly due to differences in technique of measurement. One method often used determines perstimulatory adaptation from a series of simultaneous binaural loudness balances between a continuous stimulus in the adapting ear and a stimulus intermittently presented to the test ear. The present study attempts to evaluate the effect of the characteristics of intermittency of the test stimulus upon the measured adaptation in the adapting ear. With a 4000‐cps adapting tone presented at 75‐db sensation level, 16 combinations of on‐ and off‐duration of the test tone were investigated using 11 listeners. For all experimental conditions the adapting curves showed the same general shape, with a rapid initial decline, followed by a more gradual decline reaching asymptote after 5 to 6 min. As the on‐time of the test stimulus increased, less adaptation was seen, except for off‐times of 30 sec or greater where on‐time no longer influence...

Determinaton of Lateral Pharyngeal WaIl Motion during Connected Speech by Use of Pulsed Ultrasound

Variations in the position of a point on the lateral pharyngeal wall relative to the external neck wall can be monitored by time-motion display of pulsed ultrasound. Such a portrayal is used to evaluate the lateral pharyngeal wall motion in normal and pathologic speakers during connected discourse.

Loudness Judgments of Speech and Nonspeech Stimuli

Listeners numerical estimations of loudness were compared for three sets of stimuli. The exponential loudness values for machine‐generated signals varied from 0.80 to 0.86. The loudness functions for various speech conditions, recorded at normal effort levels and played back at seven different sound‐pressure levels, varied from 0.74 to 0.84. The loudness functions of autophonically varied speech levels ranged from 0.86 to 1.20. Listeners in this study tented to respond differently to speaker‐varied speech signal levels than to the electronically varied speech signals. Therefore, it is assumed that listener loudness judgments of speaker‐varied speech levels are related to acoustic cues that vary as a function of amount of effort used by the speaker.

An EMG Electrode for the Diaphragm

A new electrode for sensing the electrical activity of the human diaphragm is described. The electrode is a bipolar surface unit employed in an esophageal approach to the fibers of the diaphragm comprising the esophageal hiatus. Procedures for its use in human subject are discussed.

Relative Perceptual Cue Strength for Voiced Stop Consonants

The relative strength of noise bursts and vocalic transitions as perception cues of word initial voiced stop consonants in CVC nonsense utterances was investigated using a tape splicing technique. All possible combinations of noise bursts and vocalic transitions in CVC utterances (using /b, d, g/ as initial consonants, /i, ae, a, u/ as vowel, and /z/ as the final consonant) were obtained by tape splicing‐substitution techniques. Temporal segmentation was accomplished by inserting a piece of splicing tape before each utterance. A sonogram was made on which the location of the tape splice in relation to the utterance was shown. Measurement of the sonogram and conversion to distance along the tape allowed for a precise tape splice for substitutions of noise bursts and vocalic transitions (cue switching). The first 10 msec of noise burst and the following 50 msec vocalic transition were systematically substituted for presentation to a group of listeners. For example, each listener heard /biz/ produced in a nor...