Peter Q. Pfordresher

Enhanced production and perception of musical pitch in tone language speakers

Individuals differ markedly with respect to how well they can imitate pitch through singing and in their ability to perceive pitch differences. We explored whether the use of pitch in one’s native language can account for some of the differences in these abilities. Results from two studies suggest that individuals whose native language is a tone language, in which pitch contributes to word meaning, are better able to imitate (through singing) and perceptually discriminate musical pitch. These findings support the view that language acquisition fine-tunes the processing of critical auditory dimensions in the speech signal and that this fine-tuning can be carried over into nonlinguistic domains.

Imprecise singing is widespread.

There has been a recent surge of research on the topic of poor-pitch singing. However, this research has not addressed an important distinction in measurement: that between accuracy and precision. With respect to singing, accuracy refers to the average difference between sung and target pitches. Precision, by contrast, refers to the consistency of repeated attempts to produce a pitch. A group of 45 non-musician participants was asked to vocally imitate unfamiliar 5-note melodies, as well as to sing a series of familiar melodies from memory (e.g., Happy Birthday). The results showed that singers were more accurate than they were precise, and that a majority of participants could justifiably be categorized as imprecise singers. Accuracy and precision measures were correlated with one another, and conditional-probability analyses suggested that accuracy predicted precision more so than the converse. Finally, performance differences across groups of singers were greater for the imitation of unfamiliar tone sequences than for the recall of familiar melodies.

Auditory Feedback in Music Performance: Evidence for a Dissociation of Sequencing and Timing

Four experiments examined temporal relationships between actions and auditory feedback in music performance. Experiment 1 incorporated phase shifts of feedback, which disrupted produced timing but not overall accuracy. Experiment 2 incorporated period shifts of pitch contents for synchronized feedback that primarily disrupted accuracy more than timing. Experiment 3 incorporated combined phase and period shifts, which caused moderate disruption to timing and accuracy and revealed interactive effects of period and phase shifts on production. A 4th experiment included all feedback conditions in the same session to confirm differences across Experiments 1-3. These results are consistent with the view that actions and their perceptual consequences are coordinated in a way that distinguishes timing (phase shifts) from sequencing (period shifts). ((c) 2003 APA, all rights reserved)

Effects of hearing the past, present, or future during music performance

Three experiments were performed to explore the effects of mismatches between actions (keypresses) and the contents of auditory feedback (pitch events) during music performance. Pianists performed melodies from memory during altered auditory feedback that was synchronized with keypresses but matched the pitch of other sequence events. Feedback direction was manipulated by presenting pitches that matched events intended for the past (delays; Experiments 1 and 3) or the future (prelays; Experiments 2 and 3). Feedback distance was manipulated by varying the absolute separation between the current event and the location of the feedback pitch. All alterations disrupted the accuracy of performance (pitch errors) more so than timing. Serial-ordering errors indicated confusions among proximal and metrically similar events, consistent with the predictions of an incremental planning model (Palmer & Pfordresher, 2003). Patterns of serial-ordering errors suggested that performers compensate for the disruptive effects of altered feedback by changing event activations during planning.

Auditory feedback in music performance: the role of melodic structure and musical skill.

Five experiments explored whether fluency in musical sequence production relies on matches between the contents of auditory feedback and the planned outcomes of actions. Participants performed short melodies from memory on a keyboard while musical pitches that sounded in synchrony with each keypress (feedback contents) were altered. Results indicated that altering pitch contents can disrupt production, but only when altered pitches form a sequence that is structurally similar to the planned sequence. These experiments also addressed the role of musical skill: Experiments 1 and 3 included trained pianists; other experiments included participants with little or no musical training. Results were similar across both groups with respect to the disruptive effects of auditory feedback manipulations. These results support the idea that a common hierarchical representation guides sequences of actions and the perception of event sequences and that this coordination is not acquired from learned associations formed by musical skill acquisition.

Native Experience with a Tone Language Enhances Pitch Discrimination and the Timing of Neural Responses to Pitch Change

Native tone language experience has been linked with alterations in the production and perception of pitch in language, as well as with the brain response to linguistic and non-linguistic tones. Here we use two experiments to address whether these changes apply to the discrimination of simple pitch changes and pitch intervals. Event related potentials (ERPs) were recorded from native Mandarin speakers and a control group during a same/different task with pairs of pure tones differing only in pitch height, and with pure tone pairs differing only in interval distance. Behaviorally, Mandarin speakers were more accurate than controls at detecting both pitch and interval changes, showing a sensitivity to small pitch changes and interval distances that was absent in the control group. Converging evidence from ERPs obtained during the same tasks revealed an earlier response to change relative to no-change trials in Mandarin speakers, as well as earlier differentiation of trials by change direction relative to controls. These findings illustrate the cross-domain influence of language experience on the perception of pitch, suggesting that the native use of tonal pitch contours in language leads to a general enhancement in the acuity of pitch representations.

Delayed Auditory Feedback and Movement.

It is well known that timing of rhythm production is disrupted by delayed auditory feedback (DAF), and that disruption varies with delay length. We tested the hypothesis that disruption depends on the state of the movement trajectory at the onset of DAF. Participants tapped isochronous rhythms at a rate specified by a metronome while hearing DAF (for piano tones) of differing lengths. Motion capture was used to analyze movement trajectories. Mean Inter-Response Intervals (IRIs) varied as an approximately sinusoidal function of feedback condition, with DAF causing slowed production for shorter delays and speeded production for faster delays. Motion capture analyses revealed that finger velocity at the time of DAF predicted the effect of DAF on mean IRI whereas finger position predicted the variability of IRIs. A second experiment in which participants were instructed to vary the timing of peak finger height confirmed that the effect of DAF on timing variability is directly influenced by the finger trajectory.

Speed, accuracy, and serial order in sequence production.

The production of complex sequences like music or speech requires the rapid and temporally precise production of events (e.g., notes and chords), often at fast rates. Memory retrieval in these circumstances may rely on the simultaneous activation of both the current event and the surrounding context (Lashley, 1951). We describe an extension to a model of incremental retrieval in sequence production (Palmer & Pfordresher, 2003) that incorporates this logic to predict overall error rates and speed-accuracy trade-offs, as well as types of serial ordering errors. The model-assumes that retrieval of the current event is influenced by activations of surrounding events. Activations of surrounding events increase over time, such that both the accessibility of distant events and overall accuracy increases at slower production rates. The models predictions were tested in an experiment in which pianists performed unfamiliar music at 8 different tempi. Model fits to speed-accuracy data and to serial ordering errors support model predictions. Parameter fits to individual data further suggest that working memory contributes to the retrieval of serial order and overall accuracy is influenced in addition by motor dexterity and domain-specific skill.

Vocal imitation of song and speech.

We report four experiments that explored the cognitive bases of vocal imitation. Specifically, we investigated the accuracy with which normal individuals vocally imitated the pitch-time trajectories of spoken sentences and sung melodies, presented in their original form and with phonetic information removed. Overall, participants imitated melodies more accurately than sentences with respect to absolute pitch but not with respect to relative pitch or timing (overall duration). Notably, the presence of phonetic information facilitated imitation of both melodies and speech. Analyses of individual differences across studies suggested that the accuracy of imitating song predicts accuracy of imitating speech. Overall, these results do not accord with accounts of modular pitch processing that emphasize information encapsulation.

Brain responses to altered auditory feedback during musical keyboard production: An fMRI study

Alterations of auditory feedback during piano performance can be profoundly disruptive. Furthermore, different alterations can yield different types of disruptive effects. Whereas alterations of feedback synchrony disrupt performed timing, alterations of feedback pitch contents can disrupt accuracy. The current research tested whether these behavioral dissociations correlate with differences in brain activity. Twenty pianists performed simple piano keyboard melodies while being scanned in a 3-T magnetic resonance imaging (MRI) scanner. In different conditions they experienced normal auditory feedback, altered auditory feedback (asynchronous delays or altered pitches), or control conditions that excluded movement or sound. Behavioral results replicated past findings. Neuroimaging data suggested that asynchronous delays led to increased activity in Brocas area and its right homologue, whereas disruptive alterations of pitch elevated activations in the cerebellum, area Spt, inferior parietal lobule, and the anterior cingulate cortex. Both disruptive conditions increased activations in the supplementary motor area. These results provide the first evidence of neural responses associated with perception/action mismatch during keyboard production.