Musical Interval Perception with Normal Hearing and Cochlear Implants

Megan E. Masterson

Committee:

Xin Luo, Ph.D. (Chair)

Beth Strickland, Ph.D.

Michael Heinz, Ph.D.

Little is known about cochlear implant (CI) users’ ability to perceive pitch intervals critical for melody recognition. We systemically investigated musical interval perception with CI and normal hearing (NH). Pitch interval discrimination was measured for various standard intervals (0-9 semitones). Interval size estimation was tested for musical intervals (1-24 semitones) using a 1-100 scale. Both rising and falling intervals were tested around 349.2 or 174.6Hz. In melodic interval adjustment, subjects adjusted a scaling factor for all the intervals in a familiar melody to produce the most correct melody, and rated if the adjusted melody was in tune using a 5-point scale.

CI users performed more poorly than NH listeners. Interval discrimination thresholds increased for larger standard intervals and were better for rising intervals than for falling intervals. Interval size estimation of both groups was affected by an interaction between frequency range and pitch direction, due to similar music listening expectancies. When listening to familiar melodies, NH listeners were sensitive to subtle interval changes and finished with an interval scaling factor around 1, while CI users preferred scaling factors >1 and cannot make the melody completely in tune. Subjects with better interval discrimination had more consistent interval adjustments and melody ratings.