Monday, 13 July 2015

The SMART Lab Singers: Improving Age-Related Hearing Difficulties Through Choir Lessons

By Saul Moshé Steinberg and Dr. Frank Russo 

This is a reproduction of an article that was originally published in RSPP Newsletter (June, 2015):

            Many older adults who experience little difficulty hearing in quiet environments will report having trouble understanding speech in the presence of competing background noise. This is often first noticed when attempting to follow a conversation at a large social gathering, in which many people are talking at the same time. While amplifying the audio signal through a modern digital hearing aid equipped with noise reduction can often go a long way towards correcting the problem, in many cases there is still a residual difficulty that persists. Part of the problem may lie in age-related changes in the brain.             

Specifically, many older adults experience a degradation of neural timing in brain mechanisms responsible for encoding the pitch of the voice. Being able to follow the pitch of a speaker's voice helps to alert the listener to conversational cues, particularly in noisy situations. Several researchers have recently proposed the idea that musical engagement may be a means of supporting this neural timing. Research has found that musicians show significantly less age-related decline in their ability to detect speech in noise as compared to non-musicians. Further, studies have shown that musicians demonstrate more precise neural timing as compared to non-musicians. Actively engaging in music requires the ability to track and discriminate
multiple sources of complex sounds, just as a listener must do when attending to a single voice among many. However, studies have not shown that being a musician directly increases the neural timing of sound. So far studies have only shown that musicians happen to show more accurate neural timing than non-musicians.
            For our current study, we are interested in determining whether older adults with mild hearing loss can show improvements in their ability to understand speech in noise as a result of short-term musical training. Specifically, we are testing the effects of singing training through group choir lessons. Since January of 2015, 14 older adults have attended weekly choir sessions over a 13-week period. Participants were also required to complete one hour of homework per week, through the use of online music training software, designed to aid users to improve voice pitch control. So far, the results are very promising. There has been significant improvement in the ability to perceive speech in noise as a result of the choir training. In addition, participants have shown improvement in their ability to discriminate pitch, which is important for tracking speaking voices. These preliminary findings suggest that short-term musical training is able to mitigate some of the age-related difficulty in hearing that is experienced by older adults.

Thursday, 11 June 2015

The Vocal Template

The US national anthem is notoriously difficult to sing. One problem is that it spans a wide range. If a singer chooses the wrong key, or drifts from the key they intended, they can find themselves struggling to hit notes at the very top or bottom of their range.

Most melodies are not as hard to sing as the US anthem. Besides having a narrower range, melodies tend to have notes spaced closely together, with not so many leaps between notes. Researchers call this universal feature of melodies pitch proximity.

SMART Lab director Frank Russo has proposed (here and here) that constraints such as pitch proximity may accommodate ease of vocal production. In other words, with or without their awareness, musicians have a template of what a melody should sound like that is based on what people can sing. It makes sense that musicians should tend to constrain their melodies in this way. Our first exposure to music-making is through singing. And it remains the easiest way of producing the music that is in your head.

What are the implications for instrumental melodies? For example, unlike with singing, on a piano it is just as easy to play a large leap than a small one. Therefore, we might expect a relaxation of pitch proximity in instrumental melodies. In fact, we recently showed that in a large sample of melodies, "skips", i.e., larger intervals that skip over one or more scale notes (e.g., from do to fa), occur more often in instrumental melodies than vocal ones.

We also showed that, when skips do occur in vocal melodies, they most often fall in the lower (i.e., more comfortable) part of the range. We refer to this as low-skip bias. Interestingly, although we found less low-skip bias in instrumental melodies, it was still apparent. This was puzzling since, unlike with singing, on many instruments (e.g., piano, strings) it is just as easy to play a high skip as a low one. 

In a follow-up study, we showed that, even though instrumentalists may not face the same motor constraints as singers, low-skip bias in instrumental melodies may still be related to the application of a vocal template. The figure below plots how often skips occur in the instrumental melodies of nineteen classical composers as a function of how much vocal music they wrote. The more vocal music a composer wrote, the more they were inclined to have low skips in their instrumental melodies (left panel), and the less they were inclined to have high skips (right panel).

These findings are consistent with the idea that, whether writing for the voice or an instrument, musicians' melodic choices are influenced by singability.

As music perception researchers, we are interested in how a listener's vocal template may impact how she listens. For example, a recent study showed people (including trained pianists) are better at remembering vocal melodies than instrumental ones. What about expectancy? Many researchers consider music's emotional power to lie in its ability to fulfill and deny our expectations. Are expectations for what note comes next in a melody shaped by an awareness of what is singable?