摘要:

The purpose of this study was to assess the effects of oral sensory deprivation upon the aerodynamic characteristics of consonant production. Three adult males with normal speech served as subjects and read a prose passage containing at least three occurences of 13 different stops and fricatives in a syllable‐initial stressed position. Sensory deprivation was achieved through a series of nerve‐block injections. Intraoral air pressure was obtained using a catheter passed through the nasal cavity. Air flow rate data were obtained using a tightly fitting face mask coupled to a pneumotachograph and a differential pressure transducer system. The results indicated that, during sensory deprivation, the intraoral air pressures, intraoral air pressure durations, and air flow rates were consistently higher than during the control condition. Very few qualitative changes in the aerodynamic patterns were observed during oral anesthesia. These results were interpreted as evidence of a mixed motor control model of speech. The temporal sequencing aspect of speech appears to be feedback independent. However, the elevated aerodynamic parameters were conceived as executive adjustments to provide increased sensory data necessary for precision in reaching appropriate articulatory targets.

ISSN:0001-4966    

DOI:10.1121/1.1903485

出版商:Acoustical Society of America    

年代:1974

数据来源: AIP

摘要:

Adult speakers participated in a spontaneous speech task in which the intensity of their auditory feedback through earphones was systematically manipulated over a 20‐dB‐SPL range. In Experiment I, Ss showed a statistically significant but slight tendency to decrease their vocal intensity as sidetone was amplified. The effect was greatest when subjects were instructed to attend to their sidetone and to compensate for any changes in loudness. In Experiment II, the same procedures were repeated except that 80‐dB‐SPL noise was added in the earphones. Addition of the noise resulted in considerably enhanced sidetone‐amplification effects, even when Ss were instructed to keep their vocal level constant. In Experiment III, several levels of noise (0, 60, 70, 80 dB SPL) were used and it was noted that the greater the noise, the more substantial were the sidetone‐amplification effects. In Experiment IV, subjects were instructed to talk either louder or softer than usual, with and without noise. The data from this last experiment indicate that it is the presence of the noise that enhances response to sidetone manipulations, and not simply the level at which the subjects are talking.

ISSN:0001-4966    

DOI:10.1121/1.1903486

出版商:Acoustical Society of America    

年代:1974

数据来源: AIP

摘要:

For vowels excited by vigorous glottal vibrations, the instant of glottal closure is tentatively identified with the moment of strongest excitation (at not too low frequencies) and worst linear predictability. Some predictor methods for its determination are reviewed, which do not always yield reliable and unequivocal results. Then Sobakin's method using the determinant of the autocovariance matrix is examined critically and reinterpreted such that the determinant is maximum if the beginning of the interval on which the autocovariance matrix is calculated coincides with the glottal closure. This hypothesis is tested by comparison with the predictor methods and by looking at the inversely filtered waveforms and the formants obtained from predictors determined on a shifted interval. The determinant method seems to be very reliable even for otherwise difficult cases, such as the vowel /u/.

ISSN:0001-4966    

DOI:10.1121/1.1903487

出版商:Acoustical Society of America    

年代:1974

数据来源: AIP

摘要:

Canine lung tissue was investigated with short pulses of ultrasonic energy at frequencies of 2.4, 5.0, and 7.4 MHz. The objective was to determine the basic ultrasonic parameters of the tissue in the frequency range of present clinical ultrasonic apparatus and to assess the possibilities of using ultrasound as an aid in the diagnosis of diseases of the lung. Attenuation coefficients and reflection losses were measured for samples of fixed inflated tissue and collapsed freshly excised tissue. The reflection loss depended strongly on the degree of inflation and, unlike the results for other soft tissues, the reflection loss varied with the frequency. The attenuation coefficients increased linearly with frequency and were an order of magnitude greater than the values for other tissues. The fixation process did not substantially change the ultrasonic parameters. Because of the very high attenuation coefficients, the usefulness of ultrasound in diagnosis may be limited to conditions which are manifested at or near the periphery of the lung. The large variation of the reflection loss with frequency is felt to be potentially very important, although further experiments using samples with specific disorders are required to determine the sensitivity of the reflection loss to changes in the condition of the tissue.

ISSN:0001-4966    

DOI:10.1121/1.1903488

出版商:Acoustical Society of America    

年代:1974

数据来源: AIP

摘要:

The frequency dependence of the ultrasonic propagation properties of canine lung inflated to a density of 0.4 g/cm3are reported. The attenuation increases exponentially with frequency, and the speed of propagation increases linearly with frequency.

ISSN:0001-4966    

DOI:10.1121/1.1903489

出版商:Acoustical Society of America    

年代:1974

数据来源: AIP

摘要:

Fresh human platelet‐rich plasma was prepared from adult blood anticoagulated with EDTA, and the platelets allowed to incorporate tritiated serotonin. Samples were sheared for 5 min at 23°C by the acoustic microstreaming field generated around submerged portions of a transversely oscillating steel wire (115‐μm radius driven at 20 kHz). Immediately following irradiation, each sample was centrifuged for 5 min to sediment intact cells and debris, and the quantity of serotonin released into the supernatant was measured using a liquid scintillation counter. There was no measurable threshold below which serotonin was not liberated, after allowances had been made for the spontaneous release of serotonin. In addition, it was found that the amount of serotonin released by irradiation alone varied with the square of the wire‐displacement amplitude, indicating that hydrodynamic shear stress and velocity gradient are probably the agents responsible for the release of serotonin (together with the simultaneous release of clot promoting and/or accelerating factors).

ISSN:0001-4966    

DOI:10.1121/1.1903490

出版商:Acoustical Society of America    

年代:1974

数据来源: AIP

摘要:

Circular vibrator sensors for atomospheric pressure, temperature, and humidity measurements by means of the natural frequency change have been developed. Uniform pressure over a circular plate supported at the edge causes an axisymmetric deformation to a quasi‐shallow spherical cap, which changes the natural frequency of the plate. A similar deformation effect is achieved with temperature or humidity by employing bimaterial construction for the plate. Change of the natural frequency is linear with the atmospheric pressure, temperature, or humidity over a relatively wide range, and the sensitivity is sufficiently high for practical applications. The devices are suitable for telemetering and digital measurement applications.

ISSN:0001-4966    

DOI:10.1121/1.1903491

出版商:Acoustical Society of America    

年代:1974

数据来源: AIP

摘要:

The effect of ring scatterers on the directivity pattern of a small sonar transducer at an air‐water surface was studied. The rings were made of styrofoam and brass. The soft (styrofoam) ring narrows the pattern significantly whereas the hard (brass) ring seems to have much less effect. This pattern narrowing may make the ring a useful device in reducing the acoustic interaction between sonar array elements.

ISSN:0001-4966    

DOI:10.1121/1.1903492

出版商:Acoustical Society of America    

年代:1974

数据来源: AIP

摘要:

Determination of the relative order of a sequence of alternated V and CV syllables is prevented by the perceptual splitting of the sequence into two distinct perceptual groupings such that vowels are heard in one spatial locus and the consonants in another. This “splitting” occurs for both monaural and binaural presentations.

ISSN:0001-4966    

DOI:10.1121/1.1903493

出版商:Acoustical Society of America    

年代:1974

数据来源: AIP

摘要:

Sine‐wave calibration in the frequency domain may result in large errors in case of digital signal processing. A practical approach based on spectrum weighting is shown to result in reasonable accuracy.

ISSN:0001-4966    

DOI:10.1121/1.1903494

出版商:Acoustical Society of America    

年代:1974

数据来源: AIP