Temporal integration in absolute identification of musical pitch

A critical analysis of Lin et al.'s (2021) failure to observe forward entrainment in pitch discrimination

Forward entrainment refers to that part of the entrainment process that outlasts the entraining stimulus. Several studies have demonstrated psychophysical forward entrainment in a pitch-discrimination task. In a recent paper, Lin et al. (2021) challenged these findings by demonstrating that a sequence of 4 entraining pure tones does not affect the ability to determine whether a frequency modulated pulse, presented after termination of the entraining sequence, has swept up or down in frequency. They concluded that rhythmic sequences do not facilitate pitch discrimination. Here, we describe several methodological and stimulus design flaws in Lin et al.'s study that may explain their failure to observe forward entrainment in pitch discrimination.

Effect of stimulus type and pitch salience on pitch-sequence processing

Using a same-different discrimination task, it has been shown that discrimination performance for sequences of complex tones varying just detectably in pitch is less dependent on sequence length (1, 2, or 4 elements) when the tones contain resolved harmonics than when they do not [Cousineau, Demany, and Pessnitzer (2009). J. Acoust. Soc. Am. 126, 3179-3187]. This effect had been attributed to the activation of automatic frequency-shift detectors (FSDs) by the shifts in resolved harmonics. The present study provides evidence against this hypothesis by showing that the sequence-processing advantage found for complex tones with resolved harmonics is not found for pure tones or other sounds supposed to activate FSDs (narrow bands of noise and wide-band noises eliciting pitch sensations due to interaural phase shifts). The present results also indicate that for pitch sequences, processing performance is largely unrelated to pitch salience per se: for a fixed level of discriminability between sequence elements, sequences of elements with salient pitches are not necessarily better processed than sequences of elements with less salient pitches. An ideal-observer model for the same-different binary-sequence discrimination task is also developed in the present study. The model allows the computation of d' for this task using numerical methods.

The Contribution of Brainstem and Cerebellar Pathways to Auditory Recognition

The cerebellum has been known to play an important role in motor functions for many years. More recently its role has been expanded to include a range of cognitive and sensory-motor processes, and substantial neuroimaging and clinical evidence now points to cerebellar involvement in most auditory processing tasks. In particular, an increase in the size of the cerebellum over recent human evolution has been attributed in part to the development of speech. Despite this, the auditory cognition literature has largely overlooked afferent auditory connections to the cerebellum that have been implicated in acoustically conditioned reflexes in animals, and could subserve speech and other auditory processing in humans. This review expands our understanding of auditory processing by incorporating cerebellar pathways into the anatomy and functions of the human auditory system. We reason that plasticity in the cerebellar pathways underpins implicit learning of spectrotemporal information necessary for sound and speech recognition. Once learnt, this information automatically recognizes incoming auditory signals and predicts likely subsequent information based on previous experience. Since sound recognition processes involving the brainstem and cerebellum initiate early in auditory processing, learnt information stored in cerebellar memory templates could then support a range of auditory processing functions such as streaming, habituation, the integration of auditory feature information such as pitch, and the recognition of vocal communications.

Pitch and plasticity: insights from the pitch matching of chords by musicians with absolute and relative pitch

Absolute pitch (AP) is a form of sound recognition in which musical note names are associated with discrete musical pitch categories. The accuracy of pitch matching by non-AP musicians for chords has recently been shown to depend on stimulus familiarity, pointing to a role of spectral recognition mechanisms in the early stages of pitch processing. Here we show that pitch matching accuracy by AP musicians was also dependent on their familiarity with the chord stimulus. This suggests that the pitch matching abilities of both AP and non-AP musicians for concurrently presented pitches are dependent on initial recognition of the chord. The dual mechanism model of pitch perception previously proposed by the authors suggests that spectral processing associated with sound recognition primes waveform processing to extract stimulus periodicity and refine pitch perception. The findings presented in this paper are consistent with the dual mechanism model of pitch, and in the case of AP musicians, the formation of nominal pitch categories based on both spectral and periodicity information.

Absolute pitch correlates with high performance on interval naming tasks

Absolute pitch, the rare ability to identify or produce a musical tone without a reference tone, has been shown to be advantageous in some musical tasks; however, its relevance in musical contexts primarily involving relative pitch has been questioned. To explore this issue, 36 trained musicians-18 absolute pitch possessors and 18 non-possessors with equivalent age of onset and duration of musical training-were tested on interval naming tasks requiring only relative pitch. The intervals to be named were either ascending or descending with separation ranging from 1 to 12 semitones and equally involved all 12 pitch classes. Three different conditions were employed; these used brief sine waves, piano tones, and piano tones preceded by a V7-I chord cadence so as to establish a tonal context. The possession of absolute pitch was strongly correlated with enhanced performance on all these tests of relative pitch. Furthermore, no evidence was found that this absolute pitch avantage depended on key, interval size, or musical context.

Absolute pitch correlates with high performance on musical dictation

Absolute pitch (AP)--the ability to name a musical note in the absence of a reference note--is a rare ability whose relevance to musical proficiency has so far been unclear. Sixty trained musicians--thirty who self-reported AP and thirty with equivalent age of onset and duration of musical training--were administered a test for AP and also a musical dictation test not requiring AP. Performance on both types of test were highly correlated (r=.81, p<.001). When subjects were divided into three groups based on their performance on the AP test, highly significant differences between the groups emerged. Those who clearly possessed AP showed remarkably high performance on the musical dictation test, the scores of those without AP varied widely, and the performance of the intermediate group of borderline AP possessors fell between that of clear AP possessors and clear nonpossessors. The findings support the hypothesis that AP is associated with proficiency in performing other musical tasks, and run counter to the claim that it confers a disadvantage in the processing of relative pitch.

A computational model of human pitch strength and height judgments

A synchronization model of pitch processing was extended to include lateral inhibition mechanisms that have been observed in the mammalian mid brain, and information integration mechanisms consistent with observed changes to response fields of mammalian auditory cortex neurons. Model parameters for the inhibition mechanisms were adapted to fit model outputs to observed temporal dynamics of pitch height difference limens from the literature. Pitch strength was defined as the certainty of pitch height judgment, and was calculated by normalizing model responses by their mean. The model was adapted to fit experimental pitch strength data reported in the literature for pure tones and harmonic complexes. It was proposed that pitch height is first estimated in relation to patterns (or templates) of tonotopic activation on the auditory nerve for particular stimulus types. These patterns are stored in long term memory. This pitch height estimation primes cortical pitch neurons to integrate finely tuned pitch information from the inferior colliculus across the periodotopic and tonotopic dimensions. Predicted pitch strength for complexes of unresolved harmonics, iterated rippled noise and amplitude modulated tones using this model also conformed to behavioral data from the literature.