Musical training is not associated with spectral context effects in instrument sound categorization.

Musicians display a variety of auditory perceptual benefits relative to people with little or no musical training; these benefits are collectively referred to as the "musician advantage." Importantly, musicians consistently outperform nonmusicians for tasks relating to pitch, but there are mixed reports as to musicians outperforming nonmusicians for timbre-related tasks. Due to their experience manipulating the timbre of their instrument or voice in performance, we hypothesized that musicians would be more sensitive to acoustic context effects stemming from the spectral changes in timbre across a musical context passage (played by a string quintet then filtered) and a target instrument sound (French horn or tenor saxophone; Experiment 1). Additionally, we investigated the role of a musician's primary instrument of instruction by recruiting French horn and tenor saxophone players to also complete this task (Experiment 2). Consistent with the musician advantage literature, musicians exhibited superior pitch discrimination to nonmusicians. Contrary to our main hypothesis, there was no difference between musicians and nonmusicians in how spectral context effects shaped instrument sound categorization. Thus, musicians may only outperform nonmusicians for some auditory skills relevant to music (e.g., pitch perception) but not others (e.g., timbre perception via spectral differences).

Dissociating sensitivity from bias in the Mini Profile of Music Perception Skills.

The Mini Profile of Music Perception Skills (Mini-PROMS) is a rapid performance-based measure of musical perceptual competence. The present study was designed to determine the optimal way to evaluate and score the Mini-PROMS results. Two traditional methods for scoring the Mini-PROMS, the weighted composite score and the parametric sensitivity index (d'), were compared with nonparametric alternatives, also derived from signal detection theory. Performance estimates using the traditional methods were found to depend on response bias (e.g., confidence), making them suboptimal. The simple nonparametric alternatives provided unbiased and reliable performance estimates from the Mini-PROMS and are therefore recommended instead.

Sensitivity to Frequency Modulation is Limited Centrally.

Modulations in both amplitude and frequency are prevalent in natural sounds and are critical in defining their properties. Humans are exquisitely sensitive to frequency modulation (FM) at the slow modulation rates and low carrier frequencies that are common in speech and music. This enhanced sensitivity to slow-rate and low-frequency FM has been widely believed to reflect precise, stimulus-driven phase locking to temporal fine structure in the auditory nerve. At faster modulation rates and/or higher carrier frequencies, FM is instead thought to be coded by coarser frequency-to-place mapping, where FM is converted to amplitude modulation (AM) via cochlear filtering. Here, we show that patterns of human FM perception that have classically been explained by limits in peripheral temporal coding are instead better accounted for by constraints in the central processing of fundamental frequency (F0) or pitch. We measured FM detection in male and female humans using harmonic complex tones with an F0 within the range of musical pitch but with resolved harmonic components that were all above the putative limits of temporal phase locking (>8 kHz). Listeners were more sensitive to slow than fast FM rates, even though all components were beyond the limits of phase locking. In contrast, AM sensitivity remained better at faster than slower rates, regardless of carrier frequency. These findings demonstrate that classic trends in human FM sensitivity, previously attributed to auditory nerve phase locking, may instead reflect the constraints of a unitary code that operates at a more central level of processing.SIGNIFICANCE STATEMENT Natural sounds involve dynamic frequency and amplitude fluctuations. Humans are particularly sensitive to frequency modulation (FM) at slow rates and low carrier frequencies, which are prevalent in speech and music. This sensitivity has been ascribed to encoding of stimulus temporal fine structure (TFS) via phase-locked auditory nerve activity. To test this long-standing theory, we measured FM sensitivity using complex tones with a low F0 but only high-frequency harmonics beyond the limits of phase locking. Dissociating the F0 from TFS showed that FM sensitivity is limited not by peripheral encoding of TFS but rather by central processing of F0, or pitch. The results suggest a unitary code for FM detection limited by more central constraints.

The role of cochlear place coding in the perception of frequency modulation.

Natural sounds convey information via frequency and amplitude modulations (FM and AM). Humans are acutely sensitive to the slow rates of FM that are crucial for speech and music. This sensitivity has long been thought to rely on precise stimulus-driven auditory-nerve spike timing (time code), whereas a coarser code, based on variations in the cochlear place of stimulation (place code), represents faster FM rates. We tested this theory in listeners with normal and impaired hearing, spanning a wide range of place-coding fidelity. Contrary to predictions, sensitivity to both slow and fast FM correlated with place-coding fidelity. We also used incoherent AM on two carriers to simulate place coding of FM and observed poorer sensitivity at high carrier frequencies and fast rates, two properties of FM detection previously ascribed to the limits of time coding. The results suggest a unitary place-based neural code for FM across all rates and carrier frequencies.

Color, Music, and Emotion: Bach to the Blues.

When people make cross-modal matches from classical music to colors, they choose colors whose emotional associations fit the emotional associations of the music, supporting the emotional mediation hypothesis. We further explored this result with a large, diverse sample of 34 musical excerpts from different genres, including Blues, Salsa, Heavy metal, and many others, a broad sample of 10 emotion-related rating scales, and a large range of 15 rated music-perceptual features. We found systematic music-to-color associations between perceptual features of the music and perceptual dimensions of the colors chosen as going best/worst with the music (e.g., loud, punchy, distorted music was generally associated with darker, redder, more saturated colors). However, these associations were also consistent with emotional mediation (e.g., agitated-sounding music was associated with agitated-looking colors). Indeed, partialling out the variance due to emotional content eliminated all significant cross-modal correlations between lower level perceptual features. Parallel factor analysis (Parafac, a type of factor analysis that encompasses individual differences) revealed two latent affective factors- arousal and valence -which mediated lower level correspondences in music-to-color associations. Participants thus appear to match music to colors primarily in terms of common, mediating emotional associations.

Learning for pitch and melody discrimination in congenital amusia.

Congenital amusia is currently thought to be a life-long neurogenetic disorder in music perception, impervious to training in pitch or melody discrimination. This study provides an explicit test of whether amusic deficits can be reduced with training. Twenty amusics and 20 matched controls participated in four sessions of psychophysical training involving either pure-tone (500 Hz) pitch discrimination or a control task of lateralization (interaural level differences for bandpass white noise). Pure-tone pitch discrimination at low, medium, and high frequencies (500, 2000, and 8000 Hz) was measured before and after training (pretest and posttest) to determine the specificity of learning. Melody discrimination was also assessed before and after training using the full Montreal Battery of Evaluation of Amusia, the most widely used standardized test to diagnose amusia. Amusics performed more poorly than controls in pitch but not localization discrimination, but both groups improved with practice on the trained stimuli. Learning was broad, occurring across all three frequencies and melody discrimination for all groups, including those who trained on the non-pitch control task. Following training, 11 of 20 amusics no longer met the global diagnostic criteria for amusia. A separate group of untrained controls (n = 20), who also completed melody discrimination and pretest, improved by an equal amount as trained controls on all measures, suggesting that the bulk of learning for the control group occurred very rapidly from the pretest. Thirty-one trained participants (13 amusics) returned one year later to assess long-term maintenance of pitch and melody discrimination. On average, there was no change in performance between posttest and one-year follow-up, demonstrating that improvements on pitch- and melody-related tasks in amusics and controls can be maintained. The findings indicate that amusia is not always a life-long deficit when using the current standard diagnostic criteria.

Musicians do not benefit from differences in fundamental frequency when listening to speech in competing speech backgrounds.

Recent studies disagree on whether musicians have an advantage over non-musicians in understanding speech in noise. However, it has been suggested that musicians may be able to use differences in fundamental frequency (F0) to better understand target speech in the presence of interfering talkers. Here we studied a relatively large (N = 60) cohort of young adults, equally divided between non-musicians and highly trained musicians, to test whether the musicians were better able to understand speech either in noise or in a two-talker competing speech masker. The target speech and competing speech were presented with either their natural F0 contours or on a monotone F0, and the F0 difference between the target and masker was systematically varied. As expected, speech intelligibility improved with increasing F0 difference between the target and the two-talker masker for both natural and monotone speech. However, no significant intelligibility advantage was observed for musicians over non-musicians in any condition. Although F0 discrimination was significantly better for musicians than for non-musicians, it was not correlated with speech scores. Overall, the results do not support the hypothesis that musical training leads to improved speech intelligibility in complex speech or noise backgrounds.

Assessing the Role of Place and Timing Cues in Coding Frequency and Amplitude Modulation as a Function of Age.

Natural sounds can be characterized by their fluctuations in amplitude and frequency. Ageing may affect sensitivity to some forms of fluctuations more than others. The present study used individual differences across a wide age range (20-79 years) to test the hypothesis that slow-rate, low-carrier frequency modulation (FM) is coded by phase-locked auditory-nerve responses to temporal fine structure (TFS), whereas fast-rate FM is coded via rate-place (tonotopic) cues, based on amplitude modulation (AM) of the temporal envelope after cochlear filtering. Using a low (500 Hz) carrier frequency, diotic FM and AM detection thresholds were measured at slow (1 Hz) and fast (20 Hz) rates in 85 listeners. Frequency selectivity and TFS coding were assessed using forward masking patterns and interaural phase disparity tasks (slow dichotic FM), respectively. Comparable interaural level disparity tasks (slow and fast dichotic AM and fast dichotic FM) were measured to control for effects of binaural processing not specifically related to TFS coding. Thresholds in FM and AM tasks were correlated, even across tasks thought to use separate peripheral codes. Age was correlated with slow and fast FM thresholds in both diotic and dichotic conditions. The relationship between age and AM thresholds was generally not significant. Once accounting for AM sensitivity, only diotic slow-rate FM thresholds remained significantly correlated with age. Overall, results indicate stronger effects of age on FM than AM. However, because of similar effects for both slow and fast FM when not accounting for AM sensitivity, the effects cannot be unambiguously ascribed to TFS coding.

Auditory deficits in amusia extend beyond poor pitch perception.

Congenital amusia is a music perception disorder believed to reflect a deficit in fine-grained pitch perception and/or short-term or working memory for pitch. Because most measures of pitch perception include memory and segmentation components, it has been difficult to determine the true extent of pitch processing deficits in amusia. It is also unclear whether pitch deficits persist at frequencies beyond the range of musical pitch. To address these questions, experiments were conducted with amusics and matched controls, manipulating both the stimuli and the task demands. First, we assessed pitch discrimination at low (500Hz and 2000Hz) and high (8000Hz) frequencies using a three-interval forced-choice task. Amusics exhibited deficits even at the highest frequency, which lies beyond the existence region of musical pitch. Next, we assessed the extent to which frequency coding deficits persist in one- and two-interval frequency-modulation (FM) and amplitude-modulation (AM) detection tasks at 500Hz at slow (fm=4Hz) and fast (fm=20Hz) modulation rates. Amusics still exhibited deficits in one-interval FM detection tasks that should not involve memory or segmentation. Surprisingly, amusics were also impaired on AM detection, which should not involve pitch processing. Finally, direct comparisons between the detection of continuous and discrete FM demonstrated that amusics suffer deficits in both coding and segmenting pitch information. Our results reveal auditory deficits in amusia extending beyond pitch perception that are subtle when controlling for memory and segmentation, and are likely exacerbated in more complex contexts such as musical listening.

Using individual differences to test the role of temporal and place cues in coding frequency modulation.

The question of how frequency is coded in the peripheral auditory system remains unresolved. Previous research has suggested that slow rates of frequency modulation (FM) of a low carrier frequency may be coded via phase-locked temporal information in the auditory nerve, whereas FM at higher rates and/or high carrier frequencies may be coded via a rate-place (tonotopic) code. This hypothesis was tested in a cohort of 100 young normal-hearing listeners by comparing individual sensitivity to slow-rate (1-Hz) and fast-rate (20-Hz) FM at a carrier frequency of 500 Hz with independent measures of phase-locking (using dynamic interaural time difference, ITD, discrimination), level coding (using amplitude modulation, AM, detection), and frequency selectivity (using forward-masking patterns). All FM and AM thresholds were highly correlated with each other. However, no evidence was obtained for stronger correlations between measures thought to reflect phase-locking (e.g., slow-rate FM and ITD sensitivity), or between measures thought to reflect tonotopic coding (fast-rate FM and forward-masking patterns). The results suggest that either psychoacoustic performance in young normal-hearing listeners is not limited by peripheral coding, or that similar peripheral mechanisms limit both high- and low-rate FM coding.

Spatial attention and environmental information.

Navigating through our perceptual environment requires constant selection of behaviorally relevant information and irrelevant information. Spatial cues guide attention to information in the environment that is relevant to the current task. How does the amount of information provided by a location cue and irrelevant information influence the deployment of attention and what are the processes underlying this effect? To address these questions, we used a spatial cueing paradigm to measure the relationship between cue predictability (measured in bits of information) and the voluntary attention effect, the benefit in reaction time (RT) because of cueing a target. We found a linear relationship between cue predictability and the attention effect. To analyze the cognitive processes producing this effect, we used a simple RT model, the Linear Ballistic Accumulator model. We found that informative cues reduced the amount of evidence necessary to make a response (the threshold), regardless of the presence of irrelevant information (i.e., distractors). However, a change in the rate of evidence accumulation occurred when distractors were present in the display. Thus, the mechanisms underlying the deployment of attention are exquisitely tuned to the amount and behavioral relevancy of statistical information in the environment. (PsycINFO Database Record