ARO Research News

We are delighted that members of spARO are spear-heading Research News highlights from recent issues of JARO, our society's journal. 

If you are interested in joining this effort, please contact the Publication's Committee representative from spARO (Mary O’Sullivan, mary29(at)stanford.edu).

Please enjoy the first ARO Research News report below.


June 2019

Interaction Between Pitch and Timbre Perception in Normal-Hearing Listeners and Cochlear Implant Users

Xin Luo, Samara Soslowsky, and Kathryn R.Pulling

Luo, X., Soslowsky, S. & Pulling, K.R. JARO (2019) 20: 57.  https://doi.org/10.1007/s10162-018-00701-3

Reported by:
Karen Chan Barrett, Ph.D. & Nicole Jiam, M.D.
University of California, San Francisco, Department of Otolaryngology-Head and Neck Surgery

Cochlear implant (CI) users find it difficult to enjoy music, and a new paper by Luo et al. explores their struggles with perception of certain acoustic dimensions. Using an innovative approach, the authors studied the interaction between pitch and timbre perception, rather than treating these two features independently.  Pitch is the perceptual correlate of fundamental frequency (or F0); timbre refers to the quality of a sound as distinct from pitch or intensity that helps to differentiate instruments or speakers from one another. In normal hearing (NH) adults, musical chords are perceived differently when played on different instruments1 and non-musician adults have a difficult time rapidly categorizing stimuli based on pitch or timbre, often confusing the two.2  In the current study, the authors designed two experiments to evaluate the relationship between pitch and timbre perception in non-musical NH listeners and CI users.  Both designs revealed better performance when the two acoustic dimensions were varied congruently (as expected for human musical predilections) rather than incongruently, despite an overall worse performance by CI users.

In experiment 1, participants completed tasks to determine fundamental frequency (F0) and spectral slope (timbre correlate) difference limens (DLs) without variations in the non-target dimension. Pitch and sharpness rankings were then separately tested when the F0 and the spectral slope of harmonic complex tones varied by the same multiple of individual DLs either congruently (e.g. higher pitch accompanied with a sharper timbre or a lower pitch with a duller timbre) or incongruently (e.g. higher pitch with a duller timbre). In general, CI users had poorer timbre and pitch perception compared to NH adults. Additionally, a symmetric and bidirectional interaction between pitch and timbre perception was found in that better performance was seen for congruent F0 and spectral slope variations. In experiment 2, CI users performed melodic contour identification (MCI) of harmonic complex tones with or without spectral slope variations.  All participants repeated pitch and timbre discrimination tasks to obtain F0 and spectral slope limens, and then completed the MCI task where the contours either had no spectral slope variations, congruent variations (i.e. spectral slope and F0 increased together or decreased together), or incongruent variations (i.e. spectral slope and F0 moved in opposite directions).  Results again demonstrated an interaction between pitch and timbre; better performance was found for congruent stimuli.  Additionally, MCI performance was significantly degraded with amplitude roving, suggesting that there may also be a perceptual interaction between loudness and pitch cues. 

In summary, this study is notable in that it explores how acoustic dimensions interact and are perceived by CI users, a crucial step towards a deeper understanding of complex sound perception in implantees. These findings are significant because they may have implications for future methods to improve music enjoyment in CI users.

1.     Beal AL. The skill of recognizing musical structures. Mem Cognit. 1985 Sep;13(5):405–12.
2.     Pitt MA. Perception of pitch and timbre by musically trained and untrained listeners. J Exp Psychol Hum Percept Perform. 1994 Oct; 20(5):976–86.