Perception of music by hearing impaired adults
Speaker: Mr Geoff Plant, AO
Date August 2, 2011
Cochlear Implants have become so sophisticated that we now take speech perception for granted. The next step is the understanding and development of music perception. (Aside: Geoff spoke with an Australian accent but whenever he said cochlea/r he pronounced it in the American way ‘Cokelear’)
Music is an area of increasing interest and research in CIs because of increasing demand. But studies indicate that around 50% of CI users are disappointed in the quality of music. (Interestingly, people born deaf who have a CI never complain about music. They have no idea what or how these people hear music.)
Example: Mrs C
- Speech was good and made a world of difference
- But music was crude
- Could hardly detect tonal intervals in music
Research of 28 people into how they found listening to music indicated
|Do you listen to music?||What is the quality of the music you hear?|
Does music matter?
Some people say that if we took music out of society nothing would change (Steven Pinka? 1997). But Confucius proposed that music gives a kind of pleasure that human nature cannot do without, while Russo said music separates humans from animals.
Peretz/Parsons researched music in ordinary people.
Music activates euphoric experiences (Levitis 2006.)
Without doubt, no matter where you go you are confronted my music. Shopping, telephone, tv, movies, radio and so on. Music has been around for a long time and pre-dates agriculture. Instruments are some of the oldest artefacts ever found. Archaeologists have found bone flutes from 2000 years ago. This indicates that music is extremely important to humans and has been practised by all cultures for thousands of years and perhaps is even more important than speech.
However, in a research of 24 people 10 people disagreed and claimed that speech was the most important for living in society. Regardless of opinion, music is part of our auditory culture.
Adult Cochlear Implantees
The importance or otherwise of music is in the overwhelming response from adult cochlear implantees. They want access to music. There is a joy in music which makes it infectious and they want the technology to improve access to fine structure.
CI – envelope strategy
This envelope strategy gives access to temporal fine structure. Basically it means breaking music down into its component parts.
- Pitch interval
However, the combination of these things needs to be looked at as a whole for music enjoyment for CIs.
Most CIs have no problem with identifying tempo and rhythm and these may enable them to identify familiar melodies (Geoff tapped out happy birthday on the desk without music or words – and it was quite easily identified).
But when it came to identifying specific instruments the result was not so good. Two studies
|Galvin & Zing?? ||Gfeller|
When it came to pitch/tone – (which in Felicity’s opinion being unable to distinguish pitch is what makes music sound funny to CIs).
CI users were asked to identify which note was higher or lower. (Gfeller research)
Note: A semitone is easiest described as one note to its nearest note on piano keyboard. (either up or down or black or white)
- The average CI user needed 7.56 semitones (range 1-24) before they could accurately say which note was higher or lower. [So this means if someone plays middle C (261Hz) on a piano the average CI user could not tell whether a note was higher until Fsharp was played. All the notes played on they keys of Csharp, D, Dsharp, E and F sounded the same so any melody played in this range would be a montone without any tonal change.]
- Whereas normal hearing people needed only 1.13 semitones (range 1-2) before they could identify a higher or lower note. [This means people could hear the small gradation in sound from a white note to its nearest next note]
- 9 CI users scored >30% and had complex tone thresholds of 4.11 semitones
Tempo - When the Saints
Geoff likened the way CIs hear music to a painting without the detail. The background basics were there but the trees and shrubs and minor detail are missing.
He played a few bars of When the Saints go Marching in, all at the same tempo and many, even hearing people could not identify the tune. However, when he put in the tempo people could then identify it. So tempo was extremely important for the enjoyment of music and most CIs had not problem identifying the tempo.
Music as a whole
Geoff said music must be seen as a whole. Music provides mood. The more of the individual parts of music a CI could access at the same time the better their experience of music. Music which is familiar, simple, has rhythm and is auditory and visual is likely to sound better than when one or a number of these aspects is missing.
Interestingly, a study with normal hearing people showed that if a familiar piece of music was played and a second of two of the music was deliberately deleted in places, most people reported not hearing the gaps in the music. Their brains filled in the missing bits. This was more likely if the music was familiar than if it was unfamiliar. So this indicates we have a sound memory. (Oliver Searle, Dennis Fitzgerald)
Geoff asked us if we stopped and listened could we ‘hear’ White Christmas and most people said yes. In another test they asked people to push a buzzer when they heard White Christmas being played in a band of white noise. 32% reported hearing it… but in actual fact it was never played, once again indicating we have a sound memory.
The best results for CIs seems to be simple music, such as a single singer, sparse accompaniment and well-defined beat. CIs prefer to see and hear the performance, so live performances, DVDs and YouTube – especially where lyrics are shown seems to make the music sound better.
Music Focus Groups – since 2005
Regular get togethers for 3-4 hours. Music is played both live and recorded and many different kinds. People report on how they experience it. The CIs enjoy these so much Geoff finds it hard to get them to go home.
‘an ear-opening experience’
‘found there are other ways to appreciate music than trying to get it to sound the way he remembered’
‘can still like it and does not have to sound like it did before to be enjoyable’
‘if I am familiar with it, I hear it perfectly’
The Focus Groups have lead to concerts especially composed for CI users which feature a great variety of new sounds.
The Noise Carriers – Oliver Searle
After the performance of Deacon, feedback from attendees meant they changed some of the music. For CIs the drumming had overwhelmed the performance and this was toned down for future concerts.
Geoff seemed to conclude that it was less to do with coding strategies and technology and more to do with exposure to music which makes it sounds better. People practise and listen to speech and expect it to be horrible at first and it gets better over time. Then they listen to music, it sounds horrible and they don’t try again. The more they listen the better it becomes.
It would seem obvious to me that if CI users can’t make a distinction in semi-tones then obviously much of the music will sound all the same. They won’t hear melody and harmony without which music is monotonal. It is my experience that listening to music will improve the hearing perception. Whether this will make it sound the way it used to sound, for everyone, is not certain.
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