Absolute Pitch Subjects Research Articles

Larger Auditory Cortical Area and Broader Frequency Tuning Underlie Absolute Pitch

Absolute pitch (AP), the ability of some musicians to precisely identify and name musical tones in isolation, is associated with a number of gross morphological changes in the brain, but the fundamental neural mechanisms underlying this ability have not been clear. We presented a series of logarithmic frequency sweeps to age- and sex-matched groups of musicians with or without AP and controls without musical training. We used fMRI and population receptive field (pRF) modeling to measure the responses in the auditory cortex in 61 human subjects. The tuning response of each fMRI voxel was characterized as Gaussian, with independent center frequency and bandwidth parameters. We identified three distinct tonotopic maps, corresponding to primary (A1), rostral (R), and rostral-temporal (RT) regions of auditory cortex. We initially hypothesized that AP abilities might manifest in sharper tuning in the auditory cortex. However, we observed that AP subjects had larger cortical area, with the increased area primarily devoted to broader frequency tuning. We observed anatomically that A1, R and RT were significantly larger in AP musicians than in non-AP musicians or control subjects, which did not differ significantly from each other. The increased cortical area in AP in areas A1 and R were primarily low frequency and broadly tuned, whereas the distribution of responses in area RT did not differ significantly. We conclude that AP abilities are associated with increased early auditory cortical area devoted to broad-frequency tuning and likely exploit increased ensemble encoding.SIGNIFICANCE STATEMENT Absolute pitch (AP), the ability of some musicians to precisely identify and name musical tones in isolation, is associated with a number of gross morphological changes in the brain, but the fundamental neural mechanisms have not been clear. Our study shows that AP musicians have significantly larger volume in early auditory cortex than non-AP musicians and non-musician controls and that this increased volume is primarily devoted to broad-frequency tuning. We conclude that AP musicians are likely able to exploit increased ensemble representations to encode and identify frequency.

No otoacoustic evidence for a peripheral basis of absolute pitch

Absolute pitch (AP) is the ability to identify the perceived pitch of a sound without an external reference. Relatively rare, with an incidence of approximately 1/10,000, the mechanisms underlying AP are not well understood. This study examined otoacoustic emissions (OAEs) to determine if there is evidence of a peripheral (i.e., cochlear) basis for AP. Two OAE types were examined: spontaneous emissions (SOAEs) and stimulus-frequency emissions (SFOAEs). Our motivations to explore a peripheral foundation for AP were several-fold. First is the observation that pitch judgment accuracy has been reported to decrease with age due to age-dependent physiological changes cochlear biomechanics. Second is the notion that SOAEs, which are indirectly related to perception, could act as a fixed frequency reference. Third, SFOAE delays, which have been demonstrated to serve as a proxy measure for cochlear frequency selectivity, could indicate tuning differences between groups. These led us to the hypotheses that AP subjects would (relative to controls) exhibit a. greater SOAE activity and b. sharper cochlear tuning. To test these notions, measurements were made in normal-hearing control (N = 33) and AP-possessor (N = 20) populations. In short, no substantial difference in SOAE activity was found between groups, indicating no evidence for one or more strong SOAEs that could act as a fixed cue. SFOAE phase-gradient delays, measured at several different probe levels (20-50 dB SPL), also showed no significant differences between groups. This observation argues against sharper cochlear frequency selectivity in AP subjects. Taken together, these data support the prevailing view that AP mechanisms predominantly arise at a processing level in the central nervous system (CNS) at the brainstem or higher, not within the cochlea.

Bridging the gap between perceptual and cognitive perspectives on absolute pitch.

Absolute pitch (AP) refers to the rare ability to identify the chroma of a tone or to produce a specific pitch without reference to keyality (e.g., G or C). Previously, AP has been proposed to rely on the distinctive functional-anatomical architecture of the left auditory-related cortex (ARC), this specific trait possibly enabling an optimized early "categorical perception". In contrast, currently prevailing models of AP postulate that cognitive rather than perceptual processes, namely "pitch labeling" mechanisms, more likely constitute the bearing skeleton of AP. This associative memory component has previously been proposed to be dependent, among other mechanisms, on the recruitment of the left dorsolateral prefrontal cortex (DLPFC) as well as on the integrity of the left arcuate fasciculus, a fiber bundle linking the posterior supratemporal plane with the DLPFC. Here, we attempted to integrate these two apparently conflicting perspectives on AP, namely early "categorical perception" and "pitch labeling". We used electroencephalography and evaluated resting-state intracranial functional connectivity between the left ARC and DLPFC in a sample of musicians with and without AP. Results demonstrate significantly increased left-hemispheric theta phase synchronization in AP compared with non-AP musicians. Within the AP group, this specific electrophysiological marker was predictive of absolute-hearing behavior and explained ∼30% of variance. Thus, we propose that in AP subjects the tonal inputs and the corresponding mnemonic representations are tightly coupled in such a manner that the distinctive electrophysiological signature of AP can saliently be detected in only 3 min of resting-state measurements.

Opposite hemispheric asymmetries for pitch identification in absolute pitch and non-absolute pitch musicians

The aim of the present study is to investigate functional laterality for pitch identification in subjects with absolute pitch (AP) and without absolute pitch (NAP). Forty-four musicians were divided into two groups (AP and NAP) on the basis of their performance in a preliminary standard AP-test. They were subsequently presented with an AP-test designed for dichotic listening, a neuropsychological technique which allows the investigation of functional hemispheric asymmetries. Dependent variables were accuracy and reaction time. It was observed that AP and NAP subjects exhibit opposite hemispheric specialization for pitch identification, AP subjects showing a bias towards the left hemisphere and NAP subjects showing a bias towards the right hemisphere. Results are discussed in the context of neuroimaging evidence of structural and functional asymmetries related to AP.

Virtual pitch extraction from harmonic structures by absolute-pitch musicians

The ability of absolute-pitch (AP) musicians to identify or produce virtual pitch from harmonic structures without feedback or an external acoustic referent was examined in three experiments. Stimuli consisted of pure tones, missing-fundamental harmonic complexes, or piano notes highpass filtered to remove their fundamental frequency and lower harmonics. Results of Experiment I showed that relative to control (non-AP) musicians, AP subjects easily (>90%) identified pitch of harmonic complexes in a 12-alternative forced-choice task. Increasing harmonic order (i.e., lowest harmonic number in the complex), however, resulted in a monotonic decline in performance. Results suggest that AP musicians use two pitch cues from harmonic structures: 1) spectral spacing between harmonic components, and 2) octave-related cues to note identification in individually resolved harmonics. Results of Experiment II showed that highpass filtered piano notes are identified by AP subjects at better than 75% accuracy even when the note’s energy is confined to the 4th and higher harmonics. Identification of highpass piano notes also appears to be better than that expected from pure or complex tones, possibly due to contributions from familiar timbre cues to note identity. Results of Experiment III showed that AP subjects can adjust the spectral spacing between harmonics of a missing-fundamental complex to accurately match the expected spacing from a target musical note. Implications of these findings for mechanisms of AP encoding are discussed.

Dichotomy and perceptual distortions in absolute pitch ability

Absolute pitch (AP) is the rare ability to identify the pitch of a tone without the aid of a reference tone. Understanding both the nature and genesis of AP can provide insights into neuroplasticity in the auditory system. We explored factors that may influence the accuracy of pitch perception in AP subjects both during the development of the trait and in later age. We used a Web-based survey and a pitch-labeling test to collect perceptual data from 2,213 individuals, 981 (44%) of whom proved to have extraordinary pitch-naming ability. The bimodal distribution in pitch-naming ability signifies AP as a distinct perceptual trait, with possible implications for its genetic basis. The wealth of these data has allowed us to uncover unsuspected note-naming irregularities suggestive of a "perceptual magnet" centered at the note "A." In addition, we document a gradual decline in pitch-naming accuracy with age, characterized by a perceptual shift in the "sharp" direction. These findings speak both to the process of acquisition of AP and to its stability.

Perception and production of virtual pitch by absolute‐pitch musicians

The ability of absolute pitch (AP) and control (non‐AP) musicians to identify and produce musical pitch from long‐term memory was investigated in three experiments. In experiment 1, subjects identified the pitch of either a missing‐fundamental complex or a highpass‐filtered piano note. Unlike control subjects, AP subjects were highly accurate (\?85%) in identifying virtual pitch even when cues were restricted to the 4th and 5th harmonics. In a second experiment, subjects produced, within 3 s, the pitch of a randomly selected musical note without an external acoustic reference through either (1) adjusting a octave‐range slider or (2) voicing/singing the target note. AP subjects, but not controls, were highly accurate (0.3 semitone) in the adjustment task. However, both AP and non‐AP subjects were extremely accurate (i.e., SD=0.97, 0.90 semitone error, respectively) in voicing the required pitches as determined from FFTs of the recorded voiced notes. In experiment 3, subjects identified pitch of solfeggio syllables at mismatched note frequencies, created by altering the sampling rate of digitally recorded voiced labels. Identification accuracy by AP subjects declined to 65%, supporting a cognitive/linguistic interference model. Implications of these findings for models of absolute pitch encoding will be discussed. [Work supported by NSF.]

Absolute Pitch and the P300 Component of the Event-Related Potential: An Exploration of Variables That May Account for Individual Differences

Our primary goal has been to elucidate a model of pitch memory by examining the brain activity of musicians with and without absolute pitch during listening tasks. Subjects, screened for both absolute and relative pitch abilities, were presented with two auditory tasks and one visual task that served as a control. In the first auditory task (pitch memory task), subjects were asked to differentiate between diatonic and nondiatonic tones within a tonal framework. In the second auditory task (contour task), subjects were presented with the same pitch sequences but instead asked to differentiate between tones moving upward or downward. For the visual control task, subjects were presented again with the same pitch sequences and asked to determine whether each pitch was diatonic or nondiatonic, only this time the note names appeared visually on the computer screen. Our findings strongly suggest that there are various levels of absolute pitch ability. Some absolute pitch subjects have, in addition to this skill, strong relative pitch abilities, and these differences are reflected quite consistently by the behavior of the P300 component of the event-related potential. Our research also strengthens the idea that the memory system for pitch and interval distances is distinct from the memory system for contour (W. J. Dowling, 1978). Our results are discussed within the context of the current absolute pitch literature.

Functional anatomy of musical processing in listeners with absolute pitch and relative pitch.

We used both structural and functional brain imaging techniques to investigate the neural basis of absolute pitch (AP), a specialized skill present in some musicians. By using positron emission tomography, we measured cerebral blood flow during the presentation of musical tones to AP possessors and to control musicians without AP. Listening to musical tones resulted in similar patterns of increased cerebral blood flow in auditory cortical areas in both groups, as expected. The AP group also demonstrated activation of the left posterior dorsolateral frontal cortex, an area thought to be related to learning conditional associations. However, a similar pattern of left dorsolateral frontal activity was also observed in non-AP subjects when they made relative pitch judgments of intervals, such as minor or major. Conversely, activity within the right inferior frontal cortex was observed in control but not in AP subjects during the interval-judgment task, suggesting that AP possessors need not access working memory mechanisms in this task. MRI measures of cortical volume indicated a larger left planum temporale in the AP group, which correlated with performance on an pitch-naming task. Our findings suggest that AP may not be associated with a unique pattern of cerebral activity but rather may depend on the recruitment of a specialized network involved in the retrieval and manipulation of verbal-tonal associations.

Absolute pitch and sex effect event-related potential activity for a melodic interval discrimination task.

Absolute pitch is a special ability which allows for special perceptual/cognitive strategies. Studies have shown differences in event-related scalp potentials between absolute-pitch (AP) and relative-pitch (RP) subjects of equal musical training. In this study, highly trained musicians (15 females/15 males) performed a melodic interval discrimination task, using intervals on-pitch in equal-tempered tuning (A4 = 440 Hz) and tuned a half-semitone sharp. Subjects identified target intervals (probability 0.2) in a series of 400 randomly transposed intervals. AP subjects were expected to perform differently across intonation conditions, whereas RP subjects were not. Event-related potentials (ERPs) were recorded from three midline sites and two lateral sites. ERPs were analyzed by principal component analysis of variance. Sex was also considered as an independent subject variable. Performance was not significantly different either by absolute pitch or sex. Reaction times did not reveal any significant interactions involving AP or sex, but showed a significant effect by response type (target/nontarget). Strong P3 activity appeared to the target melodic intervals regardless of subject group or intonation. PCA factors with maxima at 352, 511, and 709 ms were sensitive to task relevance. Males showed greater positivity than females along the midline. A significant intonation by response type by sex interaction indicated a greater spread of values for females than males, and greater similarity in response by sex for the sharp than the on-pitch intervals. AP subjects showed reduced P3 activity along the midline, but increased over lateral sites. In a difficult musical task, the ERPs were sensitive to the sex of the listeners, as well as to whether they had absolute pitch.

Absolute pitch—electrophysiological evidence

People who have the ability to label or to produce notes without any reference are considered to possess Absolute Pitch (AP). Others, who need a reference in order to identify the notes, possess Relative Pitch (RP). The AP ability is assumed to reflect a unique, language-like representation of non-lexical musical notes in memory. The purpose of this study was to examine this assumption by comparing Event Related Potentials (ERP) of musicians with and without AP, to lexical and non-lexical representation of musical material. Subjects were eighteen young adult musicians. Seven were AP and eleven RP. Auditory stimuli, presented through earphones, were piano notes (non-lexical) or a voice saying the note's name (lexical). Visual stimuli, presented on a computer display were note symbols (non-lexical) or letters (lexical). Subjects performed a number of tasks, combining the two modalities (visual and auditory) and stimulus types (lexical and non-lexical), and reaction times (RT), performance accuracy and evoked potentials were recorded. The tasks forced the subjects to transfer mental representations of musical material from one mode to another. Our most important findings were the differences, between groups, in the scalp distribution of P300 amplitudes. We conclude that absolute pitch possessors use the same internal language as relative pitch possessors, when possible, but the distribution of the underlying brain activity is different between AP and RP subjects.

Perception of Musical Intervals by Absolute Pitch Possessors

Previous studies have demonstrated that absolute pitch (AP) possessors can directly perceive the musical pitch quality (pitch class) of a tone presented in isolation. However, an isolated tone without musical context has no relevance to music, and AP ability should be examined in musically meaningful situations. In this study, AP possessors tried to identify the musical intervals between pairs of successive tones. The first tone (a reference) was either in-tune C according to the conventional pitch standard or out-of-tune C (a quarter-tone higher than standard C). The identification performance was less accurate and slower in the out-of-tune reference condition than in the in-tune condition. In contrast, AP nonpossessors showed no significant difference in performance in the two conditions, as predicted by the principle of equality under transposition. These results suggest that AP subjects tend to adhere to AP in relative pitch tasks, and that at least some AP listeners may have developed a strong dependence on AP at the sacrifice of relative pitch. AP may not have any advantage in music, in which relative pitch, not AP, is essential. Rather, AP may conflict with relative pitch and, in some cases, harm musical pitch processing.

Absolute Pitch Identification: Effects of Timbre and Pitch Region

Pitch identification by absolute-pitch (AP) possessors was tested with three different timbres. Twelve notes per octave in the equally tempered chromatic scale were presented randomly over a seven-octave range. AP subjects identified the note quite accurately but showed a considerable number of octave errors, indicating that they indeed responded primarily to pitch classes. By contrast, subjects lacking AP gave widely scattered responses, indicating that they could not perceive pitch classes at all but responded solely on the basis of the approximate pitch region (pitch height). The performance of AP subjects was best for piano tones and worst for pure tones, and responses were most accurate in the middle region of the musical pitch range. Of 12 pitch classes, white-key notes on a musical keyboard (diatonic tones in the C major scale) tended to be identified more correctly and rapidly than were black-key notes (nondiatonic tones in the C major scale). All of the AP subjects had received training on the piano since a young age. It is suggested that AP can be acquired through such early musical experience.

Absolute and relative pitch identification by absolute pitch possessors

The identification of absolute and relative pitch was investigated with absolute pitch (AP) possessors and nonpossessors as subjects. In an AP experiment, isolated tones of different pitches (including microtonal pitches) were presented as stimuli in random order. Subjects were requested to select and press a key corresponding to each stimulus on a musical keyboard. While the responses of non‐AP subjects were widely dispersed, the AP subjects could categorize the presented tones quite consistently. Specifically, they identified white‐key notes more correctly and rapidly than black‐key notes. In a relative pitch experiment, isolated melodic ascending intervals from the minor second to the octave were randomly presented. The lower tone of an interval was either middle C, F♯, or a 50‐cent higher D♯. Then non‐AP subjects performed more or less successfully and almost equally regardless of transposition. On the other hand, the AP subjects made more errors and gave longer response times when the lower tone of an interval was F♯ or the higher D♯ than when it was C. These results suggest that at least some AP possessors have difficulty in dealing with musical intervals and tend to rely upon their AP sense in the face of a relative pitch task.

SPEED AND ACCURACY OF ABSOLUTE PITCH JUDGMENTS: SOME LATTER‐DAY RESULTS

ABSTRACTNine subjects, 5 of whom claimed absolute pitch (AP) ability (4 from childhood, 1 by self‐training) were given a pitch judgment task in which they had to strike notes on the piano as rapidly as possible to match randomized tape‐recorded piano notes. Stimulus set sizes were 64, 16, or 4 consecutive semitones, or 7 diatonic notes of a designated octave. A control task involved motor movements to notes announced in advance, with the effect that set size was 1. Accuracy, measured on the basis of deviations of responses from targets, significantly differentiated AP from NAP (non‐AP) subjects at all set sizes except the control task. For both groups, accuracy increased as set size decreased. Decision times, measured as that part of total response time before a movement to the response note began, decreased as set size decreased, but did not differentiate AP and NAP subjects. The performance of the trained AP subject was not distinguishable from that of the remaining AP subjects either in accuracy or decision time. Results are discussed in terms of a two‐factor theory of AP ability whereby NAP subjects use only relative tone height as the basis of judgment but AP subjects also use standards of tone chroma stored in long‐term memory. The abnormally high channel capacities and rates of information gain for AP subjects are interpreted on the basis of transmission of information in two channels, whereas NAP subjects transmit information in only one channel.