Michael D. Hall

Evidence for auditory feature integration with spatially distributed items.

Recent auditory research using sequentially presented, spatially fixed tones has found evidence that, as in vision for simultaneous, spatially distributed objects, attention appears to be important for the integration of perceptual features that enable the identification of auditory events. The present investigation extended these findings to arrays of simultaneously presented, spatially distributed musical tones. In the primary tasks, listeners were required to search for specific cued conjunctions of values for the features of pitch and instrument timbre. In secondary tasks, listeners were required to search for a single cued value of either the pitch or the timbre feature. In the primary tasks, listeners made frequent errors in reporting the presence or absence of target conjunctions. Probability modeling, derived from the visual search literature, revealed that the error rates in the primary tasks reflected the relatively infrequent failure to correctly identify pitch or timbre features, plus the far more frequent illusory conjunction of separately presented pitch and timbre features. Estimates of illusory conjunction rate ranged from 23% to 40%. Thus, a process must exist in audition that integrates separately registered features. The implications of the results for the processing of isolated auditory features, as well as auditory events defined by conjunctions of features, are discussed.

Illusory conjunctions of pitch and duration in unfamiliar tone sequences.

In 3 experiments, the authors examined short-term memory for pitch and duration in unfamiliar tone sequences. Participants were presented a target sequence consisting of 2 tones (Experiment 1) or 7 tones (Experiments 2 and 3) and then a probe tone. Participants indicated whether the probe tone matched 1 of the target tones in both pitch and duration. Error rates were relatively low if the probe tone matched 1 of the target tones or if it differed from target tones in pitch, duration, or both. Error rates were remarkably high, however, if the probe tone combined the pitch of 1 target tone with the duration of a different target tone. The results suggest that illusory conjunctions of these dimensions frequently occur. A mathematical model is presented that accounts for the relative contribution of pitch errors, duration errors, and illusory conjunctions of pitch and duration.

Octave illusion revisited.

The octave illusion occurs when two tones an octave apart are repetitively presented dichotically in sequence such that when one ear receives the low tone the other ear simultaneously receives the high tone, with each subsequent presentation of the tones switching ear. The illusion is described as perception of a single tone whose location switches from ear to ear and whose pitch switches from one octave to the other in synchrony with the local shift [D. Deutsch, Nature 251, 307–309 (1974)]. The current study investigates various factors that may contribute to the illusion. Initial experiments replicate the illusion, examining temporal parameters critical to streaming and mapping the frequency of the pitches heard in the illusion. Results suggest that subjects hear only small shifts in pitch and lateralized position, with a major factor being fusion of the simultaneously presented stimuli. Later experiments first explored the pitch and location of a single dichotic pair of 400‐ and 800‐Hz tones, then dete...

Illusory conjunctions of musical pitch and timbre

An experiment addressed perceptual assumptions that have formed the basis of models for auditory feature integration. Musicians searched stimuli containing two lateralized tones for a target timbre and its pitch. Errors representing potential illusory conjunctions exceeded feature misperception errors. Responses were submitted to multinomial models to evaluate the contribution of guessing, illusory conjunctions, and intertone distance. Illusory conjunction models provided the most accurate data fits. Illusory conjunction rates exceeded zero, and were not affected by distance. Implications for feature binding models are discussed.

Contribution of articulatory kinematics to visual perception of stop consonants

Little is known about visual cues that are critical to the accurate categorization, and perceived quality, of individual phonemes. The current study provided a preliminary evaluation of the relationship between orofacial movements and visual perception of phonemes distinguished by place of articulation. A female talker produced VCV utterances for /b/, /d/, and /g/ consonants; a natural range of variation was obtained by producing each consonant in several vowel contexts. Peak displacement, peak closing velocity, and peak opening velocity were measured from the upper lip, lower lip, and jaw. Observers identified place and rated the perceived quality, or goodness, of each token as an example of the consonant category (1=poor,7=good). As expected, observers identified bilabials with near‐perfect accuracy, whereas they often confused alveolars and velars. More importantly, kinematic variation affected category goodness, particularly for /b/. Linear regression analyses indicated that goodness ratings within th...

Interactions between acoustic dimensions contributing to the perception of voicing

It is well known that several dimensions contribute to the classification of stop consonants as voiced or voiceless. Three Garner speeded classification experiments evaluated the nature of perceptual interactions between such dimensions. Specifically, the experiments examined the potential integrality between pairs of three critical dimensions—voice onset time (VOT), aspiration amplitude, and fundamental frequency (F0) at the onset of voicing. Only within‐category (/ka/) syllable stimuli were used to eliminate phonetic classification as a basis for subjects’ responses. Evidence was found for the asymmetric separability of VOT and F0; while variability along F0 significantly influenced VOT classification speed, variability along VOT did not similarly influence F0 classification. A similar pattern of asymmetric separability for F0 and aspiration amplitude was demonstrated, where aspiration variability did not interfere with F0 classification. In contrast, VOT and aspiration amplitude were completely integral, with variability along either dimension influencing classification speed along the other dimension. Furthermore, performance accuracy reflected a time‐intensity trade‐off between perception of VOT and aspiration. The results indicate that F0 and VOT/aspiration amplitude may contribute to two distinct sets of perceptual analyzers. Implications for phoneme perception will be discussed. [Work supported by NIH.]

Stimulus properties critical to normalization of instrument timbre

The perceptual system appears to engage in active, time‐consuming processes called normalization that maintain perceptual constancy by adjusting for source differences [e.g., Mullennix and Pisoni, J. Acoust. Soc. Am. 85, 365–378 (1989)]. Prior music research [Cho et al., J. Acoust. Soc. Am. 89, 1988(A) (1991)] demonstrated normalization for irrelevant timbre variability in chord identification. The present investigation identified important global components of instrument timbre that may be differentially subject to normalization. Using intact and physically manipulated natural stimuli, experiment 1 used similarity scaling to directly assess contributions of previously identified temporal and spectral properties of timbre. Contributions of attack and upper harmonics were evaluated. Results indicated that similarity was based primarily on the upper harmonics, with little contribution from attack functions. The relevance of these stimulus properties to normalization was evaluated in experiment 2 using an AX...

Effects of base complexity in musical duplex perception.

Duplex perception (DP) occurs when one stimulus or stimulus component contributes simultaneously to two distinct percepts. Most DP research has been used to loosely address the postulation of a phonetic module. The present musical DP experiments focus instead on the utility of DP in evaluating perceptual organization. The present investigation evaluated one variable which, according to Gestalt notions, could be critical to DP, base complexity (the number of frequency components in the base). In a modified AX task, two experiments used chord stimuli, dichotically presenting a fixed base and variable (major/minor chord) distinguishing tone on each trial. Fusion of contralateral distinguishing tones was frequent, but contrary to modularity conjectures, little evidence was found for triplex perception. Other unexpected results will be presented. Findings are discussed as they apply to (a) speech stimuli (stimulus dominance) and (b) attentional constructs (as an example of feature integration). [Work supported...

Musical duplex perception: Does perceptual dominance reflect general principles or specialized modules?

In a variant of duplex perception (DP), a phonetic module is claimed to take precedence over nonspeech processing based upon maintained phonetic perception despite discontinued nonspeech perception of the critical stimulus component. Recent attempts to replicate these findings with nonspeech stimuli fail to meet proposed criteria for stimuli used in strong demonstrations of DP. The present musical experiment first established threshold intensities for detecting the sinusoidal, chord‐distinguishing note in the context of constant‐intensity piano notes. Here, AX chord discrimination followed with distinguishing notes varying in intensity. As with speech, complex perception of chords was maintained at intensities significantly below detection threshold for component perception. Both speech and music findings could demonstrate general principles of perception, with multiple‐component stimuli preserving a strong integrative relationship between components more readily perceived as singular events with less sti...

The impact of intended emotion on dynamic changes in talker amplitude

Relatively little research has been conducted on auditory affect, and less research has focused on quantifying the nature of potential acoustic cues to emotion. A production study was conducted to address the possibility that one dynamic acoustic variable, talker amplitude, may systematically vary as a function of intended affect. Six talkers (three male, three female) were instructed to produce 200 target words with different emotional valences (e.g., joy versus sadness). Target words were phonetically balanced (PB), and each word was produced within a standard carrier phrase. Temporally specific intensity measurements were recorded for each target word. Descriptively and statistically distinct contours were obtained as a function of intended emotion. Furthermore, talkers differed in the way they produced amplitude contours for each emotion. The perceptual relevance of the observed affect‐based differences in amplitude then was evaluated. Average contours for joy and sadness were applied to an emotionall...