Ira J. Hirsh

Brain damage and the ordering of two temporally successive stimuli

Abstract Pairs of auditory and visual stimuli were presented to brain-damaged and non-brain-damaged subjects who were asked to indicate which member of the stimulus pair came first. The interstimulus interval between members of the stimulus pair was varied. Results demonstrated that performance depends upon sensory modality, spatial location of stimuli, features by which the stimuli differ, and type of aphasia present.

Studies in auditory timing: 1. Simple patterns

Listeners’ accuracy in discriminating one temporal pattern from another was measured in three psychophysical experiments. When the standard pattern consisted of equally timed (isochronic brief tones, whose interonset intervals (IOIs) were 50, 100, or 200 msec, the accuracy in detecting an asynchrony or deviation of one tone in the sequence was about as would be predicted from older research on the discrimination of single time intervals (6%–8% at an IOI of 200 msec, 11%–12% at an IOI of 100 msec, and almost 20% at an IOI of 50 msec). In a series of 6 or 10 tones, this accuracy was independent of position of delay for IOIs of 100 and 200 msec. At 50 msec, however, accuracy depended on position, being worst in initial positions and best in final positions. When one tone in a series of six has a frequency different from the others, there is some evidence (at IOI = 200 msec) that interval discrimination is relatively poorer for the tone with the different frequency. Similarly, even if all tones have the same frequency but one interval in the series is made twice as long as the others, temporal discrimination is poorer for the tones bordering the longer interval, although this result is dependent on tempo or 101. Results with these temporally more complex patterns may be interpreted in part by applying the relative Weber ratio to the intervals before and after the delayed tone. Alternatively, these experiments may show the influence of accent on the temporal discrimination of individual tones.

Pitch of tone bursts of changing frequency.

The pitch of tone bursts containing a linear change of frequency, either throughout 100% or for only a portion (5% and 25%) of the total burst duration, was studied. Pitch judgments for the tone bursts with the frequency change throughout the burst duration show that a single pitch can be assigned to the burst as long as the frequency change and duration are not too large. The single‐pitch character of such a glide deteriorates as the product of the burst duration and frequency change increases and seems to follow the change of spectra. For the bursts with short transitions, when the frequency change is not too large, the pitch assigned to the burst changes smoothly from the final to the initial frequency according to the delay of the transition onset. For larger frequency changes, bursts can be matched by either initial or final frequency, a case called separation, as distinguished from the more singular fusion. The change from fusion to separation corresponds to the change from spectra with one maximum ...

Studies in auditory timing: 2. Rhythm patterns

Listeners discriminated between 6-tone rhythmic patterns that differed only in the delay of the temporal position of one of the tones. On each trial, feedback was given and the subject’s performance determined the amount of delay on the next trial. The 6 tones of the patterns marked off 5 intervals. In the first experiment, patterns comprised 3 “short” and 2 “long” intervals: 12121, 21121, and so forth, where the long (2) was twice the length of a short (1). In the second experiment, patterns were the complements of the patterns in the first experiment and comprised 2 shorts and 3 longs: 21212, 12212, and so forth. Each pattern was tested 45 times (5 positions of the delayed tone × 3 tempos × 3 replications). Consistent with previous work on simple interval discrimination, absolute discrimination (Δt in milliseconds) was poorer the longer the intervals (i.e., the slower the tempo). Measures of relative discrimination (Δt/t,wheret was the short interval, the long interval, or the average of 2 intervals surrounding the delayed tone) were better the slower the tempo. Beyond these global results, large interactions of pattern with position of the delayed tone and tempo suggest that different models of performance are needed to explain behavior at the different tempos. A Weber’s law model fit the slow-tempo data better than did a model based on positions of “natural accent” (Povel & Essens, 1985).

Some figural properties of auditory patterns

Listeners identified one of six permutations of three frequencies, presented as brief three-note melodies. Identification performance remained high in spite of transposition of the original three frequencies throughout a two-octave range, so long as the musical intervals or frequency ratios between the adjacent pairs of frequencies remained constant. Even when those intervals were compressed or expanded, while remaining about equal to each other, identification was quite good for the range between the lowest and highest frequency of no more than approximately 1/3 octave. Performance decreased sharply when the span was much wider. Unequal intervals, where the low and middle frequencies were closer together or farther apart than the middle and high frequencies, did not retain good identification performance. When the three-tone patterns were embedded in longer sequences of seven or eight tones, the identification performance was best when the pattern occurred at the beginning or the end of the sequence, and when the range of frequencies from which the irrelevant background tones were chosen lay outside the range of pattern frequencies. Under conditions where the background frequencies were fixed and the pattern frequencies were moved, thus combining the manipulation of embedding with that of transposition of the pattern, overlap of pattern and background frequencies was still the principal cause of deterioration in performance. The findings are related to some analogies to the perceptual rules of Gestalt theory, as well as to certain aspects of musical practice.

The effect of blanking on the identification of temporal order in three-tone sequences

Trained subjects were asked to identify the temporal order of three 20-msec tones (891, 1,000, and 1,118 Hz), which were immediately followed by a fourth tone. It was found that this added tone, irrelevant to the observer’s task, decreased the identifiability of the preceding three-tone pattern, as compared with that of the same pattern in isolation. Such a blanking of the memory of the three-tone sequence was most effective when the frequency of the fourth tone was either identical to that of the first pattern tone or when it lay 1/6-1/3 octave above the highest pattern frequency. The blanking effect was strongest when the duration of the fourth tone was equal to that of the pattern components.

Pitch of sound bursts with continuous or discontinuous change of frequency

In an earlier study [I. V. Nabělek, A. K. Nabělek, and I. J. Hirsh, J. Acoust. Soc. Am. 48, 536–553 (1970)] of the pitch of a sound burst with two frequencies connected by a linear frequency change (a glide), it was found that the pair of frequencies, initial and final, are sometimes perceptually fused and sometimes perceptually separated. In the present study, the pitch of the same kind of bursts is compared with the pitch bursts in which the glide is supplanted by a pause. The method of adjustment was used. Some differences in the pitch perception of bursts with glides and those with pauses were found. Prolongation of the glide made separation more difficult and fusion easier, while prolongation of the pause made separation easier and fusion more difficult. Prolongation of either the glide or the final frequency of the burst casued the pitch to be shifted toward the final frequency, while the prolongation of the pause (0–40 msec) did not change the pitch. For an explanation of this discrepancy it seems ...

Temporal order: The effect of single versus repeated presentations, practice, and verbal feedback

Whereas Hirsh and Sherrick (1961) found that experienced Os could judge correctly the temporal order of a sound and a light presented repeatedly when the interval separating them was 20 msec, Hirsh and Fraisse (1964) found that naive Os required about 60 msec for the same accuracy of performance with single presentations of the same pair. This experiment examined the effects of single vs repeated presentations, practice, and verbal feedback on performance in the judgment of temporal order. The results indicate that performance under repeated presentation is significantly better than under single presentation, that learning effects are most pronounced during the first 4 of 16 sessions, and that the effects of feedback appear to depend on the precise wording given the S on how he is to perform.

Poststimulatory pitch shifts for pure tones

Changes in the pitch of a short tone pulse (25 msec, 1000 HZ), following a leading tone, were measured at various leading-tone frequencies and for various time intervals between the leading tone and the tone pulse. The results show that poststimulatory pitch shifts away from the pitch of the leading tone are significant and reproducible. It is suggested that poststimulatory pitch shifts may influence the results of various psychoacoustic experiments on pitch perception.

Effects of vibrator types and their placement on bone-conduction threshold measurements.

Monaural bone‐conduction threshold measurements in the quiet were obtained for 10 normally hearing young adults at both forehead and mastoid positions using two hearing‐aid‐type vibrators of different manufacture. Physical calibration data for the vibrators were obtained by other laboratories, using different Beltone artificial mastoids. Bone‐conduction force thresholds (in root‐mean‐square dynes) are reported, along with measures of both intra‐ and inter‐subject variability. [Work supported by the National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare.]