摘要:

The monaural temporal interaction of transients was investigated by using a “mirror‐image” paradigm. A pair of unequal monaural clicks in which the less intense click precedes the more intense click by a given interpulse interval (backward masking) was discriminated from an identical pair of clicks in which the more intense click precedes the less intense click by the same interval (forward masking). The functions obtained show an initial rise in discrimination as a function of increasing interpulse interval (Δt) followed by a leveling of the curve at a high discrimination level for Δt's of up to approximately 8–10 msec, followed by a decrease in discrimination to approximately 12–15 msec, followed by a second increase in discrimination at Δt's greater than 15 msec. Comparing the discrimination of mirror‐image click pairs to forward masking and to backward masking alone indicates that monaural temporal interactions exist at intermediate interpulse intervals even though forward and backward masking are no longer evident. At these intervals, the discrimination is unrelated to the perception of temporal order. The shape of the functions and the Δtrange over which it is evident are dependent upon the relative intensities of the two clicks comprising the pair. At longer intervals (greater than 15 msec), perception of temporal order is the dominant cue. Possible mechanisms are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1912662

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Test persons having their heads held in a fixed position were stimulated simultaneously from the front and the rear with identical broad‐band (music and noise) signals. Between the front and rear signal, a time delay of maximum ±880 μsec could be set. It was found that the direction of the sound sensation coincided with the angle of incidence of the first wavefront for delay times greater than about ±550 μsec. For smaller delay times, however, the direction of the sound sensation depends on the spectrum of the ear signals and can be predicted by applying the concept of directional bands.

ISSN:0001-4966    

DOI:10.1121/1.1912663

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The threshold of a 1000‐Hz sinusoidal signal masked by two or four tones placed symmetrically around the signal was investigated as a function of the frequency difference (ΔF) between consecutive maskers as well as masker level. The results concur with previous evidence that (1) the masked threshold decreases linearly as ΔFincreases for a two‐tone masker, and (2) the difference between masked thresholds is much greater than would be predicted on the basis of a simple summation of masking power or intensity. For small ΔF, the size of the difference (6–8.5 dB) did not vary greatly as level changed. At larger frequency separations, the highest levels produced more difference than lower levels. It was concluded that the difference between two‐ and four‐tone masking was (1) dependent upon the level of the maskers and the frequency separation between the maskers, and (2) independent of the masking contributed by the individual maskers.

ISSN:0001-4966    

DOI:10.1121/1.1912664

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

First‐order afferent single‐unit responses were obtained to sinusoidal one‐ and two‐frequency stimulation of the touch corpuscle in the cat. With two‐frequency stimulation, the amount of “masking” varied with the frequency and with the amplitude of the stimuli. In some instances, the addition of a second frequency decreased unit's rate of firing below the rate at which it was responding to a single frequency. The “masked” thresholds in the two‐frequency stimulation were predictable from the single‐frequency rate‐intensity functions for the unit, as were some of the decreased firing rates occurring during two‐frequency stimulation.

ISSN:0001-4966    

DOI:10.1121/1.1912665

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Pulsed tones were presented binaurally to subjects. Pure‐tone frequencies were 250, 1000, 4000, and 8000 Hz. Loudness was varied in each ear. One ear was continuously stimulated with an octave band of noise. The subject attempted to lateralize the pulsed tones in either the masked or unmasked ear. Results indicate that the pulsed tone in the masked ear had little or no effect on the lateralization until it exceeded masked threshold. Comparison of the loudness levels in the unmasked ear, required for lateralization in that ear with curves for loudness in noise, indicated that there may well have been centrally mediated loudness enhancement in the unmasked ear produced by the masking stimulus.

ISSN:0001-4966    

DOI:10.1121/1.1912666

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

Unanesthetized cats with chronically implanted epidural electrodes in the region of primary auditory cortex were stimulated with frequency‐modulated (FM) noises of varying bandwidths. The average evoked responses to these stimuli were compared with responses to tone bursts of the same center frequency and intensity. Two different noise stimuli were used: (a) bursts with rise/fall times the same as the tone burst; (b) transitions from tone to noise and back with transition times equal to tone‐burst rise time. It was found that: (1) the magnitude of the early response components increases with the bandwidth of the modulating noise, the relationship being fitted well by a power function; (2) there is a smaller power‐law type of increase in response amplitude with rms rate, noise bandwidth being held constant; (3) responses to transitions from tone to noise were quite marked, often exceeding burst responses, while responses to transitions from noise to tone were only rarely observed. These results are discussed in terms of the activity of single units in auditory cortex. A simple neuronal model is proposed to explain and unify the findings. The results are also compared with psychological loudness summation studies.

ISSN:0001-4966    

DOI:10.1121/1.1912667

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

In experiments mapping pure‐tone masked audiograms at low to moderate masker intensities, in which the signal is either a pure tone or a narrow band of noise, a notch appears on the high‐frequency side of the masker with a low point at a frequency one critical bandwidth from the masker frequency. The evidence indicates that this notch is caused by the detection, on the lower‐frequency side of the masker, of the cubic combination tones that are produced by the addition of masker and signal. At higher masker intensities, the difference tone may also be involved in accordance with the conclusions of Wegel and Lane [Phys. Rev.23, 266–285 (1924)]. Similar results are obtained when a very narrow band of noise masks a pure‐tone signal. The implication that the same process that creates combination tones creates combination bands further supports other evidence as to the mechanical nature of combination tones. The immediate further implications that combination bands or tones arising from complex maskers should produce low‐frequency masking effects in the same way as external stimuli also has been tested and confirmed over a wide range of masker intensities and spectra. The maskers consisted of pairs of tones, tones plus narrow bands of noise, pairs of narrow bands of noise, andsinglebands of noise. Some of the implications of these results for cochlear physics and critical bandwidth are outlined.

ISSN:0001-4966    

DOI:10.1121/1.1912668

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

We examine the relative role of bone conduction and tympanic conduction in underwater localization and detection by humans. Basically, we placed divers underwater and covered up various parts of the skull and outer ear with neoprene foam (an insulator of sound) and measured thresholds and localization accuracy. Sound conduction through the ear canal (tympanic conduction) appears to play only a minor role in the detection of sounds 1000 Hz and higher. Yet conduction through the canal appears to be very important for localization.

ISSN:0001-4966    

DOI:10.1121/1.1912669

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The auditory discrimination of quasiperiodic finite‐state sequences was examined for four alternative methods of encoding binary states: pulse polarity, the occurrence or nonoccurrence of a pulse, the ear to which a pulse was delivered, and interpulse interval. Except for relatively poor sensitivity for pulse polarity within low‐frequency pulse trains, all four methods of encoding led to nearly comparable discrimination. The specific method of encoding finite‐state information is apparently not critical for the auditory discrimination of quasiperiodic sequences. For each method of encoding, best performance is achieved for pulse trains of many short interpulse intervals. The detection of sequential constraints is apparently carried out primarily by means of information within high‐frequency auditory channels. Under selected conditions, the three methods based upon binary coding of periodic clock intervals are more sensitive than that based upon pulse interval coding. The auditory analysis for partial periodicities is apparently carried out over relatively constant temporal sampling intervals.

ISSN:0001-4966    

DOI:10.1121/1.1912670

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP

摘要:

The contribution of high‐frequency and of low‐frequency spectral information to the detection of temporal variability or “jitter” of auditory pulse trains was examined. Pulse trains were subjected to low‐pass, to bandpass, and to high‐pass filtering. Jitter discrimination for low‐frequency pulse trains is substantially poorer than for high‐frequency pulse trains. The reason is not that the low spectral frequencies within low‐frequency pulse trains interfere with jitter discrimination, nor that low‐frequency pulse trains contain insufficient high‐frequency spectral information. Rather, it appears that the spacing between high‐frequency spectral components of low‐frequency pulse trains is too close to permit effective resolution.

ISSN:0001-4966    

DOI:10.1121/1.1912671

出版商:Acoustical Society of America    

年代:1971

数据来源: AIP