Frequency-shift detectors bind binaural as well as monaural frequency representations

Previous psychophysical work provided evidence for the existence of automatic frequency-shift detectors (FSDs) that establish perceptual links between successive sounds. In this study, we investigated the characteristics of the FSDs with respect to the binaural system. Listeners were presented with sound sequences consisting of a chord of pure tones followed by a single test tone. Two tasks were performed. In the "present/absent" task, the test tone was either identical to one of the chord components or positioned halfway in frequency between two components, and listeners had to discriminate between these two possibilities. In the "up/down" task, the test tone was slightly different in frequency from one of the chord components and listeners had to identify the direction (up or down) of the corresponding shift. When the test tone was a pure tone presented monaurally, either to the same ear as the chord or to the opposite ear, listeners performed the up/down task better than the present/absent task. This paradoxical advantage for directional frequency shifts, providing evidence for FSDs, persisted when the test tone was replaced by a dichotic stimulus consisting of noise but evoking a pitch sensation as a consequence of binaural processing. Performance in the up/down task was similar for the dichotic stimulus and for a monaural narrow-band noise matched in pitch salience to it. Our results indicate that the FSDs are insensitive to sound localization mechanisms and operate on central frequency representations, at or above the level of convergence of the monaural auditory pathways.     

Performed or observed keyboard actions affect pianists' judgements of relative pitch

Action can affect visual perception if the action's expected sensory effects resemble a concurrent unstable or deviant event. To determine whether action can also change auditory perception, participants were required to play pairs of octave-ambiguous tones by pressing successive keys on a piano or computer keyboard and to judge whether each pitch interval was rising or falling. Both pianists and nonpianist musicians gave significantly more “rising” responses when the order of key presses was left-to-right than when it was right-to-left, in accord with the pitch mapping of the piano. However, the effect was much larger in pianists. Pianists showed a similarly large effect when they passively observed the experimenter pressing keys on a piano keyboard, as long as the keyboard faced the participant. The results suggest that acquired action–effect associations can affect auditory perceptual judgement.     

The effect of continuity on auditory stream segregation

Condition, transitions between tones were abrupt; in the “ramped” condition, successive tones were connected by frequency glides. In the “semiramped” condition, there were partial glides in frequency (as in speech). “Discrete” sequences were most likely to split perceptually into high and low streams, making order discriminations difficult. The “ramped” condition was least likely to split, and order perception was easiest. Results for the “semiramped” condition were intermediate. The discussion relates these findings to the acoustic properties of speech and to the process of auditory stream formation.     

Perceptual interactions between musical pitch and timbre.

These experiments examined perceptual interactions between musical pitch and timbre. Experiment 1, through the use of the Garner classification tasks, found that pitch and timbre of isolated tones interact. Classification times showed interference from uncorrelated variation in the irrelevant attribute and facilitation from correlated variation; the effects were symmetrical. Experiments 2 and 3 examined how musical pitch and timbre function in longer sequences. In recognition memory tasks, a target tone always appeared in a fixed position in the sequences, and listeners were instructed to attend to either its pitch or its timbre. For successive tones, no interactions between timbre and pitch were found. That is, changing the pitches of context tones did not affect timbre recognition, and vice versa. The tendency to perceive pitch in relation to other context pitches was strong and unaffected by whether timbre was constant or varying. In contrast, the relative perception of timbre was weak and was found only when pitch was constant. These results suggest that timbre is perceived more in absolute than in relative terms. Perceptual implications for creating patterns in music with timbre variations are discussed.     

Ideomotor effects of pitch on continuation tapping

The ideomotor principle predicts that perception will modulate action where overlap exists between perceptual and motor representations of action. This effect is demonstrated with auditory stimuli. Previous perceptual evidence suggests that pitch contour and pitch distance in tone sequences may elicit tonal motion effects consistent with listeners' implicit awareness of the lawful dynamics of locomotive bodies. To examine modulating effects of perception on action, participants in a continuation tapping task produced a steady tempo. Auditory tones were triggered by each tap. Pitch contour randomly and persistently varied within trials. Pitch distance between successive tones varied between trials. Although participants were instructed to ignore them, tones systematically affected finger dynamics and timing. Where pitch contour implied positive acceleration, the following tap and the intertap interval (ITI) that it completed were faster. Where pitch contour implied negative acceleration, the following tap and the ITI that it completed were slower. Tempo was faster with greater pitch distance. Musical training did not predict the magnitude of these effects. There were no generalized effects on timing variability. Pitch contour findings demonstrate how tonal motion may elicit the spontaneous production of accents found in expressive music performance.     

Rate and structure in memory for auditory patterns

Musically knowledgeable listeners heard auditory patterns based on sets of six (Study 1) or eight tones (Study 2). In the first study, listeners ordered events from patterns generated by hierarchical rule trees and which possessed different pitch space and time structures: one type (nondistance nested) was more likely to produce auditory streaming than the other (distance nested). In the second study, different listeners reconstructed pitch intervals contained in one of eight patterns. Patterns differed according to (1) levels of pitch distance occur), (2) levels of pattern contour (two), and (3) rate (two). In both studies, fast patterns with many large pitch distances were more difficult to recollect. Listeners in the second study telided to “telescope” pitch distances. Most difficult were those rapid sequences with large patch intervals combined into a changing contour (nondistance nested); these patterns streamed. A third study replicated effects due to differences in pitch distances observed in Study 2. Results were interpreted in terms of a rhythmic theory of memory.     

The speed and accuracy of perceptual decisions in a random-tone pitch task

Research in perceptual decision making is dominated by paradigms that tap the visual system, such as the random-dot motion (RDM) paradigm. In this study, we investigated whether the behavioral signature of perceptual decisions in the auditory domain is similar to those observed in the visual domain. We developed an auditory version of the RDM task, in which tones correspond to dots and pitch corresponds to motion (the random-tone pitch task, RTP). In this task, participants have to decide quickly whether the pitch of a “sound cloud” of tones is moving up or down. Stimulus strength and speed–accuracy trade-off were manipulated. To describe the relationship between stimulus strength and performance, we fitted the proportional-rate diffusion model to the data. The results showed a close coupling between stimulus strength and the speed and accuracy of perceptual decisions in both tasks. Additionally, we fitted the full drift diffusion model (DDM) to the data and showed that three of the four participants had similar speed–accuracy trade-offs in both tasks. However, for the RTP task, drift rates were larger and nondecision times slower, suggesting that some DDM parameters might be dependent on stimulus modality (drift rate and nondecision time), whereas others might not be (decision bound). The results illustrate that the RTP task is suitable for investigating the dynamics of auditory perceptual choices. Future studies using the task might help to investigate modality-specific effects on decision making at both the behavioral and neuronal levels.     

Infant music perception: domain-general or domain-specific mechanisms?

We review the literature on infants' perception of pitch and temporal patterns, relating it to comparable research with human adult and non-human listeners. Although there are parallels in relative pitch processing across age and species, there are notable differences. Infants accomplish such tasks with ease, but non-human listeners require extensive training to achieve very modest levels of performance. In general, human listeners process auditory sequences in a holistic manner, and non-human listeners focus on absolute aspects of individual tones. Temporal grouping processes and categorization on the basis of rhythm are evident in non-human listeners and in human infants and adults. Although synchronization to sound patterns is thought to be uniquely human, tapping to music, synchronous firefly flashing, and other cyclic behaviors can be described by similar mathematical principles. We conclude that infants' music perception skills are a product of general perceptual mechanisms that are neither music- nor species-specific. Along with general-purpose mechanisms for the perceptual foundations of music, we suggest unique motivational mechanisms that can account for the perpetuation of musical behavior in all human societies.     

Effects of Phonetic Similarity in the Identification of Mandarin Tones

Tonal languages differ in how they use phonetic correlates e.g. average pitch height and pitch direction, for tonal contrasts. Thus, native speakers of a tonal language may need to adjust their attention to familiar or unfamiliar phonetic cues when perceiving non-native tones. On the other hand, speakers of a non-tonal language may need to develop sensitivity to tonal correlates absent from their native system. The current study examines and compares five language groups’ perception of two synthesized Mandarin tones: the high level tone and the high falling tone. It aims to examine how listeners from tonal and non-tonal backgrounds identify and categorize acoustically equidistant pitches varying along two phonetic dimensions: pitch onset and slope. Results reveal “universal” perceptual patterns across groups and also tendencies caused by native tonal systems. Our findings confirm that L1 tonal and prosodic systems affect speakers’ sensitivity to novel perceptual cues and their abilities to discern relevant phonetic differences.     

Schema-based processing in auditory scene analysis

What is the involvement of what we know in what we perceive? In this article, the contribution of melodic schema-based processes to the perceptual organization of tone sequences is examined. Two unfamiliar six-tone melodies, one of which was interleaved with distractor tones, were presented successively to listeners who were required to decide whether the melodies were identical or different. In one condition, the comparison melody was presented after the mixed sequence: a target melody interleaved with distractor tones. In another condition, it was presented beforehand, so that the listeners had precise knowledge about the melody to be extracted from the mixture. In the latter condition, recognition performance was better and a bias toward same responses was reduced, as compared with the former condition. A third condition, in which the comparison melody presented beforehand was transposed up in frequency, revealed that whereas the performance improvement was explained in part by absolute pitch or frequency priming, relative pitch representation (interval and/or contour structure) may also have played a role. Differences in performance as a function of mean frequency separation between target and distractor sequences, when listeners did or did not have prior knowledge about the target melody, argue for a functional distinction between primitive and schema-based processes in auditory scene analysis.     

Pitch motion with random chord sequences

Perception of global pitch motion was studied through psychoacoustic experiments with random chord sequences. Chords contained either six or eight (fixed) tone elements, being sinusoidal, sawtooth-like, or Shepard tones, which were either on or off according to a probability controlled by the experimenter. Sequences of 2, 4, 5, or 8 chords were used. Identification by subjects of the perceived direction of overall pitch motion (up or down) was found to be well accounted for by a model in which the ultimate pitch motion percept is given by a sum of contributions from selected element transitions--that is, transitions between adjoining tone elements in successive time frames only. In its simplest form, this dipole contribution model has only one free parameter, the perceptual noise for an element transition, which was estimated for various acoustic tone representations and chord arrangements. Results of two experiments, which were carried out independently in two different laboratories, are reported.     

Temporal constraints on apparent motion in auditory space

The hypothesis that the extent of spatial separation between successive sound events directly affects the perception of time intervals between these events was tested using an apparent motion paradigm. Subjects listened to four-tone pitch patterns whose individual tones were sounded alternately at one of two loudspeaker positions, and they adjusted the alternation rate until they could no longer distinguish the four-tone ordering of the pattern. Four horizontal and two vertical loudspeaker separations were tested. Results indicate a direct relation between horizontal separation and the critical stimulus onset asynchrony (SOA) between successive tones within a pattern. At the critical SOA, subjects reported hearing not a four-tone pattern, but two pairs of two-note groups overlapping in time. The findings are discussed in the context .of auditory spatial processing mechanisms and possible sensory-specific representational constraints.     

The differentiation of rhythmic structure.

Listeners judged whether two five-tone nonmetric rhythms were the same or different. Each rhythm was presented one, two, or four times to study the process of perceptual differentiation. The results indicated that the listeners perceived these rhythms in terms of the grouping of the tones, and not in terms of the timing between the groups. Two rhythms that had the same perceptual grouping were judged as being identical, even if the timing between the groups was different. The perception of the groupings of tones developed gradually. If each rhythm was presented only once, then the listeners had only a global percept, focused on groups (runs) of three elements, and often judged two different rhythms as being identical. If the rhythms were presented two or four times, then the grouping of the tones became more differentiated and the listeners were less likely to judge different patterns as being identical. Thus, perception of auditory rhythmic structure appears to follow the same developmental process as the perception of visual spatial structure.     

Segregated in perception,integrated for action: Immunity of rhythmic sensorimotor coordination to auditory stream segregation

Auditory stream segregation can occur when tones of different pitch (A, B) are repeated cyclically: The larger the pitch separation and the faster the tempo, the more likely perception of two separate streams is to occur. The present study assessed stream segregation in perceptual and sensorimotor tasks, using identical ABBABB … sequences. The perceptual task required detection of single phase-shifted A tones; this was expected to be facilitated by the presence of B tones unless segregation occurred. The sensorimotor task required tapping in synchrony with the A tones; here the phase correction response (PCR) to shifted A tones was expected to be inhibited by B tones unless segregation occurred. Two sequence tempi and three pitch separations (2, 10, and 48 semitones) were used with musically trained participants. Facilitation of perception occurred only at the smallest pitch separation, whereas the PCR was reduced equally at all separations. These results indicate that auditory action control is immune to perceptual stream segregation, at least in musicians. This may help musicians coordinate with diverse instruments in ensemble playing.     

When acoustic sequences are not perceptual sequences: The global perception of auditory patterns

Warren, Bashford, and Gardner (1990) found that when sequences consisting of 10 40-msec steady-state vowels were presented in recycled format, minimal changes in order (interchanging the position of two adjacent phonemes) produced easily recognizable differences in verbal organization, even though the vowel durations were well below the threshold for identification of order. The present study was designed to determine if this ability to discriminate between different arrangements of components is limited to speech sounds subject to verbal organization, or if it reflects a more general auditory ability. In the first experiment. 10 40-msec sinusoidal tones were substituted for the vowels; it was found that the easy discrimination of minimal changea in order is not limited to speech sounds. A second experiment substituted 10 40-msec frozen noise segments for the vowels. The succession of noise segments formed a 400-msec frozen noise pattern that cannot be considered as a sequence of individual sounds, as can the succession of vowels or tones. Nevertheless, listeners again could discriminate between patterns differing.only in the order of two adjacent 40-msec segments. These results, together with other evidence, indicate that it is not necessary foracoustic sequences of brief items (such as phonemes and tones) to be processed asperceptual sequences (that is, as a succession of discrete identifiable sounds) for different arrangements to be discriminated. Instead, component acoustic elements form distinctive “temporal compounds,” which permit listeners to distinguish between different arrangements of portions of an acoustic pattern without the need for segmentation into an ordered series of component items. Implications for models dealing with the recognition of speech and music are discussed.     

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.     

Cross-octave masking of single tones and musical sequences: The effects of structure on auditory recognition

A series of experiments explored the role of structural information in the auditory recognition process, within the context of a backward recognition masking paradigm. A masking tone presented after a test tone has been found to interfere with the perceptual processing of the test tone, the degree of interference decreasing with increased durations of the silent intertone interval between the test and masking tones. In the current studies, the task was modified to utilize three-tone sequences as the test stimuli. Six test sequences were employed (LMH, LHM, MLH, MHL, HLM, HML), where L, M, and H represent the lowest, middle, and highest frequencies in the melody. The observers identified these six possible sequences when the three tones of the test sequence were interleaved with three presentations of a single masking tone. All three tones of the test sequence were drawn from the same octave, while the masking tones could be drawn from any of three octaves, symmetrical around the octave containing the test tones. Under these conditions, interference occurred primarily from masking tones drawn from the same octave as the test tones. Masking tones drawn from other octaves were found to produce little, if any, interference with perception of the test tones. This effect was found to occur only for the identification of tonal sequences. Substantial masking of single-tone targets occurred with masking tones drawn from octaves other than that containing the targets. The results make apparent the use of structural information during auditory recognition. A theoretical interpretation was advanced which suggests that, while single tones are perceived on the basis of absolute pitch, the presence of auditory structure may allow relational information, such as exact pitch intervals or melodic contour, to facilitate perception of the tonal sequence.     

The differentiation of rhythmic structure

Listeners judged whether two five-tone nonmetric rhythms were the same or different. Each rhythm was presented one, two, or four times to study the process of perceptual differentiation. The results indicated that the listeners perceived these rhythms in-terms.of the grouping of the tones, and not in terms of the timing between the groups. Two rhythms that had the same perceptual grouping were judged as being identical, even if the timing between the groups was different. The perception of the groupings of tones developed gradually. If each rhythm was presented only once, then the listeners had only a global percept, focused on groups (runs) of three elements, and often judged two different rhythms as being identical. If the rhythms were presented two or four times, then the grouping of the tones became more differentiated and the listeners were less likely to judge different patterns as being identical. Thus, perception of auditory rhythmic structure appears to follow the same developmental process as the perception of visual spatial structure.     

Temporally nonadjacent nonlinguistic sounds affect speech categorization

Speech perception is an ecologically important example of the highly context-dependent nature of perception; adjacent speech, and even nonspeech, sounds influence how listeners categorize speech. Some theories emphasize linguistic or articulation-based processes in speech-elicited context effects and peripheral (cochlear) auditory perceptual interactions in non-speech-elicited context effects. The present studies challenge this division. Results of three experiments indicate that acoustic histories composed of sine-wave tones drawn from spectral distributions with different mean frequencies robustly affect speech categorization. These context effects were observed even when the acoustic context temporally adjacent to the speech stimulus was held constant and when more than a second of silence or multiple intervening sounds separated the nonlinguistic acoustic context and speech targets. These experiments indicate that speech categorization is sensitive to statistical distributions of spectral information, even if the distributions are composed of nonlinguistic elements. Acoustic context need be neither linguistic nor local to influence speech perception.     

Tonotypic cortical representation in man (case report)

Cortical stimulation—evoked perception of tones differing in pitch suggests that the perception of pitch may be discretely organized in the human auditory parakoniocortex. Findings, obtained from a neurosurgical patient undergoing temporal lobectomy, are discussed with reference to anatomical and functional considerations of the auditory parakoniocortex in humans. These tonotypic findings are potentially significant since, as previously reported (see references in Discussion section), auditory sensations have not been analyzed in relation to perceptual categories of pitch. Address correspondence to: Department of Speech Pathology and Audiology, Marquette University, Milwaukee, Wisconsin 53233.