Standard separation index

Hearing Research, 2006

Phillips and Hall [Psychophysical evidence for adaptation of central auditory processors for interaural differences in time and level, Hear. Res., 202 (2005) 188-199.] recently described the frequency-specific, selective adaptation of perceptual channels for interaural differences in level (ILD) and time (ITD). Psychometric functions for laterality based on ITD or ILD were obtained before and after exposure to adaptor tones of two frequencies presented alternately and highly lateralized to opposite sides. Following adaptation, points of perceived centrality (PPCs) were displaced towards the sides of the adaptor tones, and in opposite directions for the two frequencies. That is, laterality judgements showed a shift away from the adapted side, particularly for test cue values near the middle of the range. These data were congruent with a two-channel, opponent-process model of sound laterality coding. The present study used the same general paradigm to explore the independence of perceptual ITD and ILD processing. Psychometric functions for laterality based on ITD or ILD were obtained for each of two frequencies concurrently, before and after exposure to adaptor tones lateralized using the complementary cue. Once again, PPCs derived from the psychometric functions were displaced towards the sides of the adaptor tones, consistent with an opponent-process account of sound laterality coding. The size of the adaptation effect was at least as great as that described in the earlier study. Thus, a quarter cycle ITD adapting stimulus effected a 3 dB shift in the mean ILD-based PPC, and a 12 dB ILD adapting stimulus effected a 100 ls shift in the mean ITD-based PPC. These data offer new evidence concerning interaction in the processing of ITDs and ILDs.

Perception & Psychophysics, 1982

'-'IW'IW~2 _ ('IW~)2 ' b = 'IW'IW~z-'IWz'IW' IW'IW~2 _ ('IW~)2 ' (3) (4) The threshold of a given perceptual variable, tp, is the value of the associated physical variable,~, corresponding to the value of tp having a probability, p, of being detected equal to .5. To find the threshold, the observer is shown the so-called variable stimuli (VSs) in random order, one after the other. The VSs are physical objects in which generally only one variable is varied, for example, the frequency of a sound, the weight of an object, etc. As a rule, n values, h~2' ••• ,~n, of such a variable are chosen so that D = 'IW'IW~z-'IW~'IWz, IJ. = W(2p-l)-zV2nW, V p(1-p)

Journal of Sensory Studies, 1999

... In terms of equivalent d' values (Ennis 1993), which can be estimated from the mean R-indices in Table 1 the decline in performance for Experiment I was approx. ... Neuropsychologia 23, 667-672. DOTY, RL, FRYE, RE and AGRAWAL, U. 1989. ...

The Journal of the Acoustical Society of America, 2006

Electronic mail: [email protected] (2004) investigated the effects of ITD ENV manipulation (the ITD FS was random and uncontrolled) in electric hearing by presenting acoustic stimuli via unsynchronized speech processors. They showed that JNDs differed between NH subjects (19 µs) and CI listeners (259 µs and 384 µs, best JNDs for CI listener S2 and S1, respectively) and depended on the type of stimulus (lowest for click trains, highest for speech or noise bursts).

The Journal of the Acoustical Society of America, 1977

In an earlier paper, we examined the distribution of binaural resolving power by measuring threshold increments of interaural delay as a function of overall delay [Hafter and De Maio, J.AcouSt. Soc Am. 57, 181-187 (1975)]. In the current study, similar measures were made for interaural increments of intensity. As before, the stimuli were bandpass clicks of either low (0.1-2 kHz) or high (3-4 kHz) frequency. For overall interaural differences as great as 24 dB, it seems that performance was based on the interaural differences, and not on the monaural increments/decrements that are concommitant with a binaural change in level. As was the case with time, sensitivity to interaural intensity was reasonably constant across the range tested, indicating that, unlike the case 'for vision, spatial resolution in the auditory system is not concentrated in the center. A simple binaural trading ratio which converts intensity to time can be shown to fit the data for low-frequency clicks quite well. However, the fit to high frequencies is so poor as to suggest that separate mechanisms were used for detecting time and intensity. Finally, a number like the binaural masking-level difference (MLD) was computed for the two kinds of clicks. Surprisingly, the MLD's for low and high frequencies were a similar 7.2 and 8.0 dB. PACS numbers: 43.66.Pn, 43.66.Cb were dichotic acoustic transients with bandwidths of either 0.1-2 or 3-4 kHz. Theshold increments of Arid were then determined for various fixed values of IID.

Perception & Psychophysics, 1973

The role of the standard in a fixed-standard experiment of auditory amplitude discrimination was examined by varying the proportion of trials on which it was presented. The results suggest that the Os may use different perceptual strategies, depending on the availability of the standard. While they did better on trials containing a standard regardless of the proportion of such trials, their accuracy on both "standard-present" and "standard-absent" trials was positively related to the probability of the particular type of trial. These results conflict with the claim of advocates of the roving-standard paradigm that the 0 in the fixed-standard experiment does not use the standard but, rather, compares the variable with a long-term referent built up over many trials. The introduction of a second pair of tones, making it a random-standard experiment, produced considerable response bias tied to the stimulus level and to an overall deterioration in performance.

Hearing Research, 2014

Sound localization in the horizontal plane is mainly determined by interaural time differences (ITD) and interaural level differences (ILD). Both cues result in an estimate of sound source location and in many real-life situations these two cues are roughly congruent. When stimulating listeners with headphones it is possible to counterbalance the two cues, so called ITD/ILD trading. This phenomenon speaks for integrated ITD/ILD processing at the behavioral level. However, it is unclear at what stages of the auditory processing stream ITD and ILD cues are integrated to provide a unified percept of sound lateralization.

Journal of the Acoustical Society of America, 1974

Listeners monitored a rapid series of tone bursts to detect intensity increments in a 1000-Hz tone presented in continuous white noise. The data were analyzed using TSD statistics and suggest that performance was close to that observed in more conventional paradigms. Possible violations of TSD assumptions are discussed and it is concluded that TSD may be used to analyze the performance of people listening to rapid trains of tone bursts as well as when discrete trials are used. Subject Classification: 65.50, 65.75. would be a maximum d • at some nonzero ISI. If performance were reduced in this way, it would have im-1577

Journal of experimental psychology, 1991

In Experiment 1, 2 groups of human subjects were trained to respond to 1 of 2 light intensity stimuli, S2 or S4, and then were tested for generalization with a randomized series of increasing values from SI to Sll. Both groups, including the group trained to respond to the dimmer value, showed peak shifts to a brighter more centrally located test stimulus. In Experiment 2, which used line angle stimuli, both the size of the difference between S+ and Sand the range of test stimuli that extended beyond S+ were varied. The larger the S+-S-separation and the larger the range, the greater was the peak shift obtained. In Experiment 3, training involved an S-(line angle) surrounded by 2 S+ values with testing symmetrical about the training values and covering either a narrow or a wide range. The wide range produced greater peak shifts in both directions from S-. All 3 experiments support an adaptation-level interpretation of intradimensional discrimination learning and generalization test performance in human subjects. Related work with animals suggests the presence of similar processes.

Hearing Research, 1987

Two alternative methods for the measurement of neural sensitivity to interaural intenstty differences (IIDa) were used to obtain IID-sensitivity functions for samples of excitatory-inhibitory (EI) neurons from the central nucleus of the inferior colhculus and the primary auditory cortex of the cat. In one, the EMI-constant method, intensity was held constant in the ear providing excitatory input and varied above and below that level in the other ear. In the alternative (ABI-constant) method, intensity at the two ears was varted symmetrically about a constant base intensity. in a manner roughly approximating the pattern of changes that occur when a free-field stimulus is moved in azimuth from the median sagittal plane. For neurons with monotonic or near-monotonic rate-intensity functtons for the excitatory ear. the two methods generated IID-sensitivity functions that were identical or near-identical by a number of quantitative criteria. For neurons with non-monotonic rate-intensity functions, however. the IID functions generated by the two methods were very different: those produced by the EMI-constant method were monotonic, whereas those generated by the ABI-constant method were non-monotonic and sharply peaked. The advantages and disadvantages of the two methods, and the implicattons of the results for the neural encoding of IIDs and for the azimuthal sensitivity of El neurons with non-monotonic rate-intensity functions, are discussed.