James F. Curtis

Responding to One of Two Simultaneous Messages

Twenty operators were given a task which required answering one of two simultaneous voice messages. The task was performed under a variety of conditions produced by combinations of four experimental “aid” variables: horizontal spatial separation of the sound sources, aural shaping filters which made the tone quality different in each channel, visual cues which indicated the channel about to call the operator, and facilities to “pull down” a desired message from the initial source into a headphone or a loudspeaker near the operators ear. It was found that the use of horizontal separation and/or the filtered messages greatly improved the operators performance. Visual cues had no apparent effect on ability to answer the message except when used with pull down facilities. The pull down facilities aided the operator to some extent. Some speculations are advanced about the nature of recognizing and attending to a message in the presence of another message.

Pressure‐flow relationships in two models of the larynx having rectangular glottal shapes

The pressure-flow equations used in computer simulation studies of phonation lack experimental validation. Two polyester resin models of the laryngeal airway with rectangular glottal ducts were constructed in order to obtain the relationships between translaryngeal pressure drop and volume flow through the airway. The results are in disagreement with the early estimates of Wegel [Bell Syst. Tech. J. 9, 207-227 (1930)], but match the predictions given by Ishizaka and Matsudaira [SCRL Monograph No. 8 (1972)] to within approximately +/- 10% for typical translaryngeal pressures for speech, with larger discrepancies being found for the model with the larger glottal diameter. The equation given by van den Berg et al. [J. Acoust. Soc. Am. 29, 626-631 (1957)] may not be properly compared because their supraglottal pressure hole location may have been different from that used in the present study. The data from the two models also are compared to recent empirical studies using an enlarged model of the larynx [J. Gauffin et al., Conference on Vocal Fold Physiology, Madison (1981)].

Effects of selected vocal disguises upon spectrographic speaker identification

This research was designed to investigate the effects of selected vocal disguises upon spectrographic speaker identification. The experiment consisted of open‐trial, spectrogram‐matching tasks with 15 ’’reference’’ and 15 ’’matching’’ speakers. The speakers produced two sentence sets in six different ways: (1) normal‐speaking mode, (2) old‐age disguise, (3) hoarse disguise, (4) hypernasal disguise, (5) slow‐rate disguise, and (6) free disguise of his own choosing. The reference spectrograms were always undisguised speech samples; the matching spectrograms were either disguised or undisguised. Four trained spectrographic examiners completed the matching tasks. The results revealed that the examiners were able to match speakers with a moderate degree of accuracy (56.67%) when there was no attempt to vocally disguise either utterance. The inclusion of disguised speech samples in the matching tasks significantly interfered with speaker‐identification performance. However, certain voice disguises were more eff...

Electromyographic‐Cinéfluorographic Investigation of Velar Function during Speech Production

Cinefluorographic films of velar movement were made simultaneously with surface electromyographic recordings of velar muscle contraction during the production of selected syllables and sustained vowel and nasal phonemes. The data were analyzed to determine (1) the extent of variation in velar position during the production of various phonemes in relation to alterations in duration and phonetic context; (2) the extent of variation in velar electromyographic activity during the same speech utterances; and (3) the extent to which velar elevation and electromyographic activity covary during the production of sustained vowel and nasal phonemes and during alterations in duration and phonetic context. These data are discussed in relation to the hypothesis, advanced by certain investigators, that the velum acts in an all‐or‐none (ON‐OFF) fashion.

Factorial Study of Speech Perception

A battery of speech and tonal tests was administered to 90 male Navy recruits between the ages of 17 and 24. This battery included verbal facility tests and intelligibility tests of (1) distorted (clipped, interrupted, and reverberant) speech; (2) noise‐masked speech; (3) filtered speech; (4) speech at threshold; and (5) speech in the presence of distracting speech (limericks, stuttering). Also included were individual and group pure tone audiometer tests and the Seashore Tests of Musical Talent. Pearson Product‐Moment Correlation Coefficients were computed for all possible pairs of tests in the battery. The resulting intercorrelation matrix was factor‐analyzed by means of the complete centroid method and rotated to orthogonal simple structure by means of the Varimax method. The more important of the 8 factors that were extracted were: “Resistance to Distortion,” “Distraction,” “Acuity,” “Individual Audiometry,” “4000 cps Hearing Loss,” and “Verbal Facility‐Seashore.” Differences between the results of th...

Pressure‐flow relationships within static models of the larynx

Pressure‐flow relationships using steady flow through polyester resin models of the larynx were investigated. Model geometry was based on x‐ray data. Flow ranged from 20 to 1000 cc/s, resulting in translaryngeal pressure drops from 0.03 to 40 cm H2O. Translaryngeal pressure drop predictions from Ishizaka and Matsudaira [SCRL Monograph, No. 8 (1972)] and van den Berg, et al. [J. Acoust. Soc. Am. 29, 626–631 (1957)] fell within 37% and 50%, respectively, of the data. For an intermediate size glottis, the overall average percent difference between the measured and predicted pressure drops was less than 5% when compared with Ishizaka and Matsudairas predictions, and less than 30% when compared with van den Bergs predictions. For a larger glottis, the corresponding percentages were 21% and 37%. We conclude that: (1) both theories underestimate the translaryngeal pressure drop, and (2) the data support the predictions of Ishizaka and Matsudaira more than the predictions of van den Berg et al.

Speech Pathology and Basic Research on Speech

Speech pathology is concerned with deviations in speaking behavior that significantly reduce communication effectiveness. Organic causes of speech disorders include defects of peripheral speech organs, neuromuscular defects, and sensory defects—for example, significant hearing loss. In many cases, there is no apparent organic defect sufficient to explain the speech disorder. An understanding of abnormal speech obviously presupposes knowledge concerning the normal processes of speech and language. Thus, the speech pathologist has a particular interest in research concerning the speech‐generating processes and their relationships to the nature of the speech output. Recent work concerning speech articulation and the probable relationships of underlying neural events to the control of articulatory processes is of special significance to speech pathology. Studies directed toward better understanding of the fundamental time segments of the speech stream is of particular interest because of implications concerni...