摘要:

A direct‐magnitude production scaling technique was employed to study the relationships of three speech variables: intraoral air pressure, lingual pressure, and sound pressure during changes in vocal effort. Selected CVC syllables containing two lingua‐alveolar stop consonants /t/ and /d/ were produced at various effort levels and during periods of increased auditory masking. Exponents of the effort function for intraoral air pressure and for lingual pressure (1.7 and 1.8, respectively) suggest that speakers can monitor effort during speech production. Exponents for production of sound‐pressure level (0.56) are similar to results of previous investigations. Systematically greater average values for /t/ contexts during both masked and nonmasked conditions distinguished intraoral pressure characteristics for consonants differing in force of articulation.

ISSN:0001-4966    

DOI:10.1121/1.1912973

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

A number of studies in the literature have stated that the duration of a vowel is a significant cue to the voicing characteristic of the consonant that follows it. The present study investigated the effect of varying preceding vowel duration upon the perception of word‐final stops, fricatives, and clusters in synthetic speech. A variety of minimal CVC (C) pairs was synthesized and the vowel of each was varied over a range of values derived from durations found in real‐speech samples. It was found that, regardless of the cues for voicing or voicelessness used in the synthesis of the final consonant or cluster, listeners perceived the final segments as voiceless when they were preceded by vowels of short duration and as voiced when they were preceded by vowels of long duration. Discrimination tests revealed that when the voicing characteristic is cued by vowel duration, perception is continuous rather than categorical.

ISSN:0001-4966    

DOI:10.1121/1.1912974

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The intelligibility of nonsense syllables was investigated as a function of the place in the speech waveform where the signal was switched from one ear to the other. The results demonstrated that the place at which switching occurred had essentially no effect on the identification of either the consonants or the vowels in the stimuli. In view of these findings it is unlikely that phonological rules are applied before the signals to the two ears are combined in the auditory system.

ISSN:0001-4966    

DOI:10.1121/1.1912975

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Stimulus segments (burst, and burst plus 100 msec of vowel) were isolated from words with initial and final /p,t,k/, and presented to listeners for identification. For the burst alone, initials were identified better than finals and /t/ showed the highest level of identification. Also, in many instances vowels could be identified on the burst portions, giving perceptual evidence for coarticulation. With the additional 100 msec, the level of identification, as was expected, was high. Providing phonotactic context, in some instances, raised this level of identification.

ISSN:0001-4966    

DOI:10.1121/1.1912976

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Laboratory and field experiments are described in which toadfish hearing was investigated. The threshold to tonal stimuli determined in the laboratory using a conditional heart rate technique agreed closely with the field‐determined threshold using an unconditional behavioral response. Below 150 Hz, the hearing threshold was about 100 dBre1 μN/m2. Above 200 Hz, it increased rapidly at about 22 dB/oct. In addition to the tonal threshold experiments, a threshold to prerecorded playbacks of toadfish sounds was measured in the field. This threshold was about 15 dB higher than the tonal threshold in the same frequency range.

ISSN:0001-4966    

DOI:10.1121/1.1912977

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Explosive acoustic sources were used to obtain echoes from aggregations and schools of commercially important marine fish. Narrow‐band spectral analysis of the echoes from these targets revealed significant structure in the frequency range from 200 Hz to 5 kHz. The targets were partially captured after the acoustic tests; three yielded northern anchovy (Engraulis mordax), one consisted of a mix of anchovy and jack mackerel (Trachurus symmetricus), and the last sample contained an aggregation of seven species of rockfish (Sebastes), whitefish (Caulolatilus princeps), and a striped seaperch (Embiotoca lateralis). The results of the direct biological sampling were combined with theoretical predictions for the resonant swimbladder response and compared with the experimentally observed resonances.

ISSN:0001-4966    

DOI:10.1121/1.1912978

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Thermal factors are believed to play a dominant role in the development of the structural and functional effects of irradiation of the nervous system with focused ultrasound at low‐megahertz frequencies. Similar mechanisms are postulated to underlie the effects of irradiation in methacrylate, which is frequently used as a test material to evaluate the influence of various factors on the results obtained. This study was undertaken to determine if thermal mechanisms alone can explain the development of trackless focal alterations (lesions) and all of their measurable characteristics in plastic as well as in brain. A purely thermal model is assumed and analytical prediction of lesion development and lesion size and shape for varying values of ultrasonic and thermal constants and controllable variables (frequency, focusing, dosage, target depth, etc.) is attempted. An empirical equation to describe the axial and radial ultrasonic energy distribution at the focus in water is derived. Appropriate heat transfer equations are developed for temperature distributions resulting from ultrasonic irradiation. The computed temperature profiles are plotted against nondimensionalized parameters. Temperatures at the lesion boundary were determined experimentally. Lesion dimensions read off the computed temperature profiles at the measured lesion boundary temperature are compared with experimental data. Agreement of analysis and data shows that, within the range of ultrasonic parameters used in this study, the development of lesions in the brain are explained by thermal mechanisms.

ISSN:0001-4966    

DOI:10.1121/1.1912979

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The real part of the complex dynamic modulus for frequencies 50–10 000 Hz was derived from viscoelastic wave‐propagation constants in whole frog skeletal muscle, in order to provide a material function characteristic of the dynamic longitudinal viscoelastic behavior of resting skeletal muscle in the higher‐frequency range. The method of measuring the phase velocity and attenuation coefficient of longitudinal waves propagated along the longitudinal axis of thin muscles is described. The results showed that there were significant viscoelastic effects between 50 and 5000 Hz with some leveling off above 5000 Hz, as indicated by the frequency dependence of the wave propagation constants. The relaxation time spectrum derived from the dynamic modulus‐frequency function showed that about half of the relaxation times were less than 1 msec. The results were generally consistent with other studies based on the time course of stress relaxation and on the relationship between sinusoidal stress and strain.

ISSN:0001-4966    

DOI:10.1121/1.1912980

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Instead of presenting a perceptual stimulus to which a subject must assign numerical response, he is given a number from 1 toNand must then generate corresponding motor response. The amounts of information transmitted in producing acoustical signals varying in only one dimension, either their SPL (between 50 and 105 dB) or their frequency (between 50 and 6000 Hz), are compared to the amounts of transmitted information in identifying analogous signals.

ISSN:0001-4966    

DOI:10.1121/1.1912981

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

A dummy head was constructed after new measurements of thresholds of hearing. Correlated structures were found in the thresholds of hearing for all subjects. It was possible to average the identifiable structures and to adjust the frequency responses of the dummy‐head to the average threshold of hearing.

ISSN:0001-4966    

DOI:10.1121/1.1912982

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP