David R. Soderquist

The precedence effect: Revisited

The precedence effect, as investigated by Wallach et al. [Am. J. Psychol. 62, 324–336 (1949)] was studied in three experiments. Experiment I was a replication of the original work of Wallach et al. Although the first click pair appears to dominate the perception of the position of the lateral image, the effect of the first click pair does not appear to ‘‘offset’’ or ‘‘cancel’’ the effect of the second click pair in terms of producing a lateral image at midline. The data are consistent with Zurek’s [J. Acoust. Soc. Am. 67, 952–964 (1980)] proposal that the binaural system is less sensitive to the interaural temporal difference of the second click pair. Experiment II indicated that the effect of the first click pair on lateral judgments still dominates that of the second click pair when the images are judged to be off midline. In all of these studies, the variability of the data is quite high. Experiment III showed that the first click pair also led to a larger change in masked thresholds (masking‐level dif...

Frequency analysis and the critical band

The objective of the study was to examine the performance of two groups of Ss on an auditory frequency analysis task. The groups were differentiated in terms of musical training and background. Predictions based on the assumption that frequency analysis is dependent upon the critical band were derived from two synthetically produced inharmonic complex stimuli. Results indicate that nonmusicians are inferior to professional musicians in their ability to analyze complex waveforms. The results suggest that musicians possess critical bands which are rectangular in shape and approximately 20% narrower in width than published values.

Physiological noise as a masker of low frequencies: the cardiac cycle.

This study quantified the effects of a physiological masker, the heartbeat, on the detectability of a low‐frequency tone (100 Hz, 100‐msec duration). Using a YES‐NO signal detection paradigm, binaural sensitivity (d′) was examined as a function of the temporal location of the signal onset within the cardiac cycle. The independent variable was the temporal delay in signal onset following the subjects own EKG R wave. Signal delays were selected (0.0 to 0.8 sec in 0.1‐sec steps) and presented to four subjects. Results reveal depressed sensitivity with signal delays of 0.0, 0.3, and 0.7 sec following the EKG R wave. In contrast, maximum sensitivity occurred near 0.5 sec following the R wave. The results were discussed in terms of physiological masking produced by valve closures within the heart.

The Utility of Within-Subjects Variables: Estimates of Strength

Procedures to estimate the magnitude of a treatment effect are examined for analysis of variance designs which have repeated-measures. It is shown that the estimate of the magnitude of an effect logically follows from the expected mean squares associated with the design in question. In particular, it is argued that the estimate of utility (strength of effect) for a within-subjects variable should be adjusted to reflect the underlying ANOVA model; viz., the inter-subject variability should be removed from the utility estimate.

Transient complex and pure tone pitch changes by adaptation

The effect of pitch adaptation by a complex stimulus was examined in two experiments. In experiment 1, a monaural complex tone pitch change was measured after ipsilateral or contralateral complex stimulus adaptation. While ipsilateral adaptation resulted in pitch changes away from the pitch of the adapting stimulus, no pitch occurred for contralateral adaptation. The precision of pitch matching was reduced by both ipsilateral and contralateral adaptation. Experiment 2 examined whether the complex tone pitch changes in experiment 1 could be accounted for by pitch changes induced in the pure tone components. Results indicated that changes induced in the pure tone components were too small to account for the complex tone shift magnitudes found in experiment 1. These results support a degree of independence of complex tone pitch from the pitches of the pure tone components. Results also supported pitch extractor specialization for a particular ear of stimulus presentation.

Forward masking in young children: Rocketship psychophysics

A three-alternative forced choice forward masking procedure was embedded in an arcade-style rocketship video game. Human subjects were categorized into five groups; adults and 5-, 6-, 7-, and 8-year-old children. The masker was a 500-msec noise that simulated rocket engines and the 20-msec, 500-Hz sinusoidal signal was achirp from agremlin. The gremlin hid, at random, in one of the three rockets. Subjects responded and interacted with the game by touching the rocket hiding the gremlin. Results revealed that masked thresholds decreased for all groups as a function of the interstimulus interval. The reliability of the psychophysical approach was confirmed and a developmental trend lends support to the hypothesis that auditory processing improves as a function of age. Children’s auditory filters were suggested to be functionally larger than those of adults.

Practice Effects and Signal Detection Indices in an Auditory Vigilance Task

Performance of nine subjects was investigated over ten 90‐min vigilance sessions. Trends in performance over and within sessions were examined in terms of three dependent measures: (a) correct detections, (b) errors of commission, and (c) theory of signal detectability (TSD) indices d′ and β. The results indicate that: (1) TSD accounts for performance over sessions but is inadequate in accounting for within‐sessions decrements unless basic tenets of the theory are altered. (2) Performance decreases within sessions for the first 30 min, regardless of practice. (3) Within sessions decrements may be accounted for by assuming either a decrease in the observers activation level, a distracted mode of observing, or both.

Encoding and pitch strength of complex tones

Pitch perception in the human was examined with respect to the level of neural analysis and pitch strength of various complex tones. In binaural conditions, three‐component complex stimuli were presented to each ear in such a way that if a central processor determined pitch from the combined information from the two ears, one pitch would be perceived. If the pitch processor attended to the information from each ear separately, two pitches would be perceived (corresponding to the fundamental at each ear). Two pitches were perceived and the importance of peripheral encoding for pitch perception was supported. Subjects judged the strength of monaurally and binaurally presented stimuli as a function of the spectral region of the frequency components, number of components per complex, and the spacing between components. Pitch strength was discussed in terms of recent theoretical models of pitch.Subject Classification: 65.54, 65.56, 65.62.

Complex pitch—Effects of context and experience

Complex pitch perception is influcenced not only by the physical composition of the stimulus, but also by the context in which the stimulus occurs, and by previous pitch stimuli to which the listener has been exposed. Three complex pitch effects will be discussed: (1) Pitch for nonsimultaneous harmonics presented in quiet and in a noise background; (2) short‐term complex pitch adaptation effects; (3) long‐term changes in complex pitch perception where the pitch associated with one complex tone changes to the pitch associated with a second complex, after the two complex tones are paired and presented to the listener over several hours of listening. Findings will be related to pitch theories, plasticity of pitch perception, and possible organization of complex pitch “channels.”

Psychophysical tuning functions, dichotic stimuli, and pulsation thresholds

Using a dichotic mode of stimulus presentation, four psychophysical tuning curves were obtained: input filter pattern, input extension pattern, output filter pattern, and output extension pattern [J. Verschuure, Acustica 49, 288–295 (1981)]. Stimulus parameters for all tuning functions were: durations 60 ms, rise/decay 10 ms, interstimulus interval (delta‐t) 0.00 ms (no overlap between pulsator offset and signal onset). Stimuli were presented in sequential pairs (pulsator then signal), alternating between ears; e.g., left ear (pulsator‐signal), right ear (pulsator‐signal), left ear (pulsator‐signal), etc. The alternation between ears was temporally controlled to insure no overlap (delta‐t = 0.00 ms) between signal offset in one ear and pulsator onset in the other. Pulsation thresholds were obtained by the method of adjustment for each of the four tuning patterns. Results indicate that pulsation threshold patterns could be perceived when the stimuli were presented dichotically, i.e., the perception of “continuity” was synthesized by central processes. Tuning patterns, generated with the dichotic stimuli and based on the centrally synthesized pulsation thresholds, appear to be similar to those in the literature. Contrasts of the four tuning patterns will be presented.