Re: CI Music Perception

[Bob Carlyon <bob.carlyon@xxxxxxxxxxxxxxxxx>]

Dear List (& Ray),


I would like to make a few comments about enjoyment of music by cochlear
implant users, and specifically with regard to Ray Goldsworthy's
observations.


It is clear that some cochlear implant users do continue to enjoy music,
but:

(i) Except for a very few "stars" (of whom Ray may well be one)
this enjoyment  is unlikely to be based on variations in pitch. When
rhythmic cues are removed, melody recognition by CI users is usually very
poor. Pitch discrimination thresholds when tested experimentally by
varying the pulse rate 
applied to a single channel is very poor; a DL of around 7% at 100 Hz is
average, and most users can't do the task at all for baseline rates above
about 300 Hz. Pitch discrimination for sounds played via the speech
processor is typically worse, rather than better than these values, as
are DLs for modulation rates imposed on high-rate pulse trains

(ii) CIs are relatively good at preserving rhythm (cf. Ray's choice of
musical types). To quote Ed Burns: "cochlear implants make
all music sound like rap". 

(iii) There will be anecdotes of those who enjoy music more and those who
enjoy it not so much (I'm not immune here: when I told one user we were
using acoustic simulations of speech through a CI she said "well, if
you want to do the same for music just rattle a few tin cans).  I
append abstracts of papers I just found (but haven't read), which may
give list members an overview of the general success observed

Regarding the vocode simulations of cochlear implants: I agree with Ray
that this may well not be qualitatively what implant users hear. Neither
of us can know that (unless Bob Shannon visited Ray's home as a child
before he lost his hearing - perhaps dressed as Santa Claus?). I do think
though that they do a reasonable job of conveying the same sorts of
information, as Ray says. Generally, the results obtained don't differ
markedly between the different carriers (sine wave, noise, bandpass
filtered pulse trains), so these may not be crucial.

Hope this helps

Bob

Ability of nucleus cochlear implantees to recognize music
Fujita S, Ito J
ANNALS OF OTOLOGY RHINOLOGY AND LARYNGOLOGY
108 (7): 634-640 Part 1 JUL 1999

Document type: Article    Language: English    Cited References: 13    Times Cited: 3    

Abstract:
Eight adults with cochlear implants participated in experiments to test their ability to recognize music. Some subjects showed good ability to recognize songs that were sung with instrumental accompaniment but poor ability to recognize songs played on an electronic keyboard without Verbal cues, indicating that they were recognizing the songs by verbal cues rather than by musical qualities such as tones and melodic intervals. This conclusion was strengthened by the finding that subjects were barely able to distinguish between songs with the same rhythm and pitch range, and they showed poor ability to discriminate musical intervals. (The closest discrimination was 4 semitones.) Subjects had good ability to distinguish among the synthesized sounds of various musical instruments played on the electronic keyboard. We speculate that subjects could distinguish the various musical instruments in the same way they distinguish among human Voices using spectrographic patterns such as formants or maxima.

Music perception in adult cochlear implant recipients
Leal MC, Shin YJ, Laborde ML, Calmels MN, Verges S, Lugardon S, Andrieu S, Deguine O, Fraysse B
ACTA OTO-LARYNGOLOGICA
123 (7): 826-835 OCT 2003

Document type: Article    Language: English    Cited References: 11    Times Cited: 1    

Abstract:
Objective-To evaluate musical perception in adult cochlear implant (CI) recipients, i.e. perceptual accuracy for pitch, timbre, rhythmic patterns and song identification.

Material and Methods-Twenty-nine adult patients were included in this transverse single-center study. Evaluative measures included tests assessing ability to discriminate pitch, rhythm and timbre and to identify nursery songs with and without verbal cues. Performance scores were correlated with duration of deafness, duration of implantation, speech discrimination and musical perception skills.

Results-A total of 38% of patients reported that they did not enjoy listening to music with their device and 86% presented lower scores of listening habits after implantation. We found positive correlations between musical background and pitch identification and identification of nursery songs played by piano. We also found positive correlations between speech discrimination and rhythm, timbre and identification of nursery songs with verbal cues.

Conclusion-Trends in the patterns of correlation between speech and music perception suggest that music patterns are differentially accessible to CI users. New processing strategies may improve this.

Dr. Bob Carlyon
MRC Cognition and Brain Sciences Unit
15 Chaucer Rd.
Cambridge CB2 2EF
England
Phone: (44) 1223 355294 ext 831
Fax:   (44) 1223 359062
email: bob.carlyon@xxxxxxxxxxxxxxxxx