摘要:

Two studies were performed to determine the parameters affecting the sensitivity and variability of Békésy thresholds. The first study was concerned with the effects of varying period, duty cycle, and frequency on threshold measurements obtained using pulsed tones and was done to derive an “optimal” pulsed tone. The second study compared thresholds taken using the optimized pulsed tone to those obtained with continuous tones. The effects of varying attenuation rate with both types of presentation were also investigated. Pulsed tones were found to yield superior threshold measurements both in terms of greater sensitivity and less intratest variability. Also, continuous tone thresholds were found to be susceptible to changes in attenuation rate whereas pulsed tone thresholds were not.

ISSN:0001-4966    

DOI:10.1121/1.1911629

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The ability to lateralize a tonal signal against a white‐noise background was investigated by presenting that signal at different intensities to the two ears and asking the listener to indicate which ear received the more intense signal. The signal (500 cps, 250 msec) was gated on every trial during the single observation interval, and the more intense signal was equally likely to be presented to the leaf ear as to the right. Both the interaural phase relation of the signal and the magnitude of the interaural intensive difference were variables of interest. For signals both in phase (S0) and 180° out of phase (Sπ), six‐point psychometric functions were determined with interaural intensive differences of 3. 6. and 12 dB In addition, detection functions were obtained for each of these interaural conditions using a single‐interval forced‐choice technique. Particularly for the smaller interaural intensive differences. S0 and Sπ signals led to lateralization functions of quite different forms. Noise: in phase interaurally (N0), continuous 44 dB SPL/cycle.

ISSN:0001-4966    

DOI:10.1121/1.1911630

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Listeners attempted to discriminate sounds that differed in the rate at which frequency changed from an initial to a final value, in sound bursts that were much longer than the frequency transition itself. The results indicate that the rate of change of frequency for which the discriminability is optimum depends upon the extent of frequency change, from the initial and final frequencies. For small frequency differences, the optimum appears at small glide rates—i.e., at transition durations in the range of seconds; for large frequency differences, the optimum discriminability occurs at high glide rates, at transition durations of some tens of milliseconds. It seems that there are two mechanisms involved in hearing for perception of frequency transitions.

ISSN:0001-4966    

DOI:10.1121/1.1911631

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

A comparison was made of the effectiveness of noise in masking (1) a change in the frequency of a sinusoid, and (2) a change in the repetition rate of a pulse train that had no low‐frequency energy. The sinusoid and the pulse train had the same pitch. It was found that, whereas the change in the pitch of the sinusoid was better masked by low‐frequency noise, the change in the residue pitch produced by the filtered pulse train was more easily masked by high‐frequency noise. These results replicate the findings of Small and Campbell (1961). We conclude as they did that the basis for the residue pitch of the pulse train is its high‐frequency components. In a second experiment, a pair of sinusoids was used to produce the residue pitch. The same masking technique was employed, and again the results indicate that the residue pitch is not based on a nonlinear distortion component, but rather is based on information being transmitted through high‐frequency components (2100 Hz).

ISSN:0001-4966    

DOI:10.1121/1.1911632

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

An attempt was made to assess the effect of an imposed amplitude envelope on the binaural fusion of dichotic tone signals and noise signals. The envelope was imposed by an electronic switch at three rise/decay rates—10 msec, 25 msec, and 50 msec. The duration of the signals was such that there was no constant amplitude portion for any signal. The tonal signals covered a range from 250 to 2000 Hz. The noise was either high passed or low passed at 1000 Hz. Only the imposed envelope was delayed at one ear—not the microstructure of the signal. For tonal signals, the maximum envelope delay time for which the signal still yields a single stationary image is definitely a function of the envelope slope, being approximately 5–7 msec for the 10‐msec slope; 10–12 msec for the 25‐msec slope; and 15–20 msec for the 50‐msec slope. For the two lesser slopes, there is also an envelope delay range for which the image moves across the head from leading ear to lagging ear. For the signals with noise microstructure, behavior of the image is more complex than for tones, but a number of tentative principles emerge, most of them amenable to further testing: (1) The position of the signal is predominantly determined by the interaural envelope delay. (2) Correlated microstructure (noise from the same noise generator) definitely increases the likelihood that a signal with large interaural envelope delay will fuse into a single image, even though the delay and the microstructure should yield different positions for the image. (3) Signals presented at higher sensation level tend to split into two at smaller envelope delays when microstructure information indicates the signals are different. (4) For the type of signal used here, maximum single‐image envelope delays are greater for low‐frequency microstructure than for high‐frequency microstructure. For these signals, singleness of image and position of image appear to be analyzed separately, the information being combined later into a single perceptual impression.

ISSN:0001-4966    

DOI:10.1121/1.1911633

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Auditory intensity discrimination at 2000 Hz was determined for the left and right ears of normal listeners at intensity levels of 23 to 78 dB sound‐pressure level (SPL) in the presence of contralateral white noise and sawtooth noise from quiet to 63 dB SPL. It was hypothesized that contralateral noise might affect the left temporal lobe in a manner analogous to left‐temporal excision, resulting in improved intensity discrimination only in the left ear. Results showed that intensity discrimination was significantly improved in both ears by contralateral noise for subjects receiving test tones of 38 dB and above. Contralateral noise did not improve intensity discrimination in subjects who received test tones of 38 dB and below, but the difference limens for the left ear were significantly smaller in both quiet and noise. The original hypothesis was not upheld, and further study of the limiting conditions for the enhancement of differential sensitivity by contralateral noise is suggested. The finding of left‐ear superiority for lower‐level test tones is discussed in relation to right‐hemisphere dominance for nonverbal stimuli.

ISSN:0001-4966    

DOI:10.1121/1.1911634

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The rate of change of fundamental frequency with respect to transglottal air pressure was determined for a single male speaker by sinusoidally varying buccal air pressure while the speaker sustained short episodes of pronation at various fundamental frequencies. The speaker phonated at two levels of “effort,” i.e., “soft” and “loud” phonation with and without auditory feedback. The sensitivity of the larynx to variations in transglottal air pressure varied from 3 to 18 Hz/cmH2O. Fundamental frequency was most sensitive to variations in transglottal air pressure at high frequencies and in the “soft” mode of phonation. The minimum transglottal air pressure for sustained phonation was 2–3 cmH2O. These results are consistent with some earlier studies and a recent theoretical model of laryngeal activity. These results further indicate that variations in subglottal air pressure and adjustments in laryngeal muscular tension both play a role in regulating fundamental frequency during normal speech.

ISSN:0001-4966    

DOI:10.1121/1.1911635

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

A fundamental distinction between speech sounds depends on whether the excitation is a noise source or a quasiperiodic one. The noisy or voiceless sounds are presumably produced with an opened and quiescent larynx, while for voiced sounds the larynx is closed down and in rapid oscillation. Direct evidence of this has come from motion pictures taken through the open mouth, a method obviously limited to particular sounds. Running speech can be studied by a transillumination technique. A fiber‐optics bundle or a miniature incandescent bulb introduced into the laryngeal vestibule through the nose illuminates the glottis, while a photocell placed below the thyroid cartilage registers the variable light transmitted through the glottis and the tissues of the neck. The “glottograms” so obtained are compared with simultaneously recorded acoustic waveforms and intraoral air‐pressure traces to determine how the voiced‐voiceless distinction correlates with the closed‐versus‐open states of the larynx.

ISSN:0001-4966    

DOI:10.1121/1.1911636

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Multimode guided‐wave patterns in bounded ultrasonic specimens have been shown to interfere with phase delay measurements made by the pulse superposition method and the pulse‐echo‐overlap method. The phase shifts associated with the nodes in the multimode guided wave patterns invalidate the McSkimin ΔTcriterion for the choice of the proper cyclic matching between echoes when the nodes are near the echoes used. The adverse effect of nodes upon the McSkimin criterion has been documented by extensive measurements employing shear waves in square barsand thick plates. In free‐wave propagation without nodes, the ΔTcriterion remains valid. A method employing video pulses to establish the proper cyclic match for rf measurements has been developed to supplement or replace the McSkimin ΔTcriterion in all cases including those of adverse specimen geometry. Advantages and limitations of the video overlap criterion are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1911637

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

This paper describes a piezoelectric shaker consisting of a combination of damped resonant cylindrical elements. Material characteristics and design parameters are chosen so that the resonances of the combined elements overlap to provide “good” motion over a wide frequency range. Data from three shakers are presented to show how a suitable set of shakers can be used for the calibration of vibration pickups at frequencies up to 100 kHz.

ISSN:0001-4966    

DOI:10.1121/1.1911638

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP