Presentation on theme: "Implications of rate pitch on musical perception and auditory object formation in cochlear implants Bomjun Kwon, Trevor Perry Gallaudet University Dept."— Presentation transcript:
Implications of rate pitch on musical perception and auditory object formation in cochlear implants Bomjun Kwon, Trevor Perry Gallaudet University Dept of Hearing, Speech and Language Washington DC The study was supported by NIDCD (R03 DC009061)
Music in cochlear implants Image source: FDA.gov
Bold statement regarding CI users music appreciation They can recognize familiar tunes in carefully prepared conditions. – Not many voices, not much harmony – Dominated by rhythmic components The process of music listening involves pattern-matching (highly top-down) – More effortful than enjoyable
Fundamental problem Perception is based only on place pitch and does not punctuate the pitch accurately necessary for musical events Harmonicity is absent
Temporal pitch as an alternative Can temporal pitch work? – Limited to ~ 300 Hz – Not as salient as place+temporal (Burns & Viemeister, 1983) – Maybe can be used to represent low pitch notes? – At least the pitch can be accurately represented – Less top-down pattern matching task
Demonstration of temporal pitch Pijl & Schwarz (JASA, 1995; HR, 1995) Pijl (EH 1997) – CI users can recognize melodies from temporal pitch sequences presented on single channel – Their musical interval judgment can be as good as NH. But…. So what?
Temporal harmonics (Rate harmonics) Idea: Deliver rate pitch melody on multiple channels with harmonic ally related rates EL pps pps pps130.8 pps EL pps pps pps130.8 pps Why are we trying this? To facilitate grouping stimulation on two channels
Experiment 1: Conditions Minor 2nd Major 3rd Perf 5th Major 7th Perf 8th Unison H: Stimulation on two channels are more easily grouped if their rates are harmonically related
Procedure 4 Nucleus users with substantial musical experience 5 familiar tunes All temporal (rate) pitch lower note on apical El Higher note on basal El Happy Birthday Frère Jacques Mary had a little lamb Do-re-mi song When the saints go marching in
Procedure For each melody, 6 buttons are given on screen, corresponding to 6 conditions 6 were randomly arranged in each time. Subjects click the button to play Repeats are allowed Once done, they type consonance rating for each button—1: complete cacophony, 10: perfect harmony (almost one sound) Each melody was repeated 3 times.
Octave (harmonic) Hypothesis supported!
Punchline Electrical stimulation on two channels can be perceptually grouped when stimulation rates are harmonically related. Findings from Experiment 2 are even cooler but don’t have time today. – Please stay tuned until next time I give a talk. Conclusion Rate pitch has potentially important implications in auditory grouping with CIs. Temporal harmonics… maybe future
Observations / more stories Rate pitch percept is not immediate. – Takes a little “warm-up” time. Different range of rates for each subj – Some prefer higher rate (>200 pps) Rates 400~500 pps do enrich sound quality when used as a harmonic rate even though they alone cannot elicit pitch percept. In terms of sound quality, rates and electrode position do not appear to be independent. – They definitely prefer some choice than others.