In part 1, the work of Hormann and his colleagues was discussed showing that if a person disliked or was negatively predisposed to music, then their temporary threshold shift (TTS) was greater than if they were neutral or positive towards it. This “third” factor that may contribute to noise or music exposure- with the sound level (in dBA) and the duration of exposure being the first two- appears to be an element (albeit a tertiary one) in noise or music exposure. Hormann, along with his colleagues, found that disliking something was the issue that made them more susceptible to auditory damage and not that liking the music made it less damaging. Liking of the offending stimuli resulted in a TTS that was similar to that obtained when the stimulus was considered to be neutral.
Swanson, Dengerink, Kendrick, and Miller (1987): Swanson and his colleagues knew that a certain pop musical group was coming to town and they also knew (suspected?) that some would love this music and others would not. (Apparently professors know everything about their students!) Tickets for the show were given to the students- some who hated this music, and others who loved/liked it. The students were arrayed randomly throughout the concert hall (actually the University of Washington stadium) and all wore dosimeters. The students’ hearing was tested before the concert, and again immediately after the concert, in order to obtain a measure of their temporary hearing loss (or TTS). All students wore noise/music dosimeters in order to ensure that the sound level that the students were exposed to was a controlled factor.
And similar to the study by Hormann and his colleagues cited in part 1 of this blog series, the students who hated the music had statistically greater TTS than those who loved or “merely” liked the music. Again, it seems that having a negative emotional perspective made these students more susceptible to temporary hearing loss.
Stated another way, musicians who have a negative predisposition to their chosen craft are more likely to have greater TTS (and even perhaps greater permanent hearing loss eventually, although this last point is still quite controversial) than their happier musical colleagues. Axelsson and Lindgren (1981) compared an age- and experience-matched group of rock musicians to classical musicians and found that given a certain pass/fail criterian, 13% of rockers had permanent hearing loss whereas 43% of classical musicians had a permanent hearing loss. Axelsson and Lindgren suggested that this may be related to a rather negative work environment that many classical musicians may find themselves in as compared with a pop or rock group that presumably may find their music more enjoyable. In a classical environment, the music is selected by someone else for them and this may not be as enjoyable as the rock or pop music that a (friendlier?) group may be playing, especially if they actually wrote the music themselves.
So why is this happening? The reasons are not clear. There is some research suggesting that the disliking of music may cause increased levels of catecholamines to be generated in the cochlea, which would reduce the blood supply and thereby reduce the amount of available oxygen for its optimal metabolic function. This suggestion comes from the study of “stressed” guinea pigs and not from humans- I am not sure how they stressed out the guinea pigs, but I imagine that a mean-looking ferret was involved.
Other research indicates that other biochemical processes- perhaps higher levels of the neurotransmitter substance glutamate – that may be created as a result of stress-related changes and hormones.
At this point, we are unsure of the biochemical reasons, but it does seem that as an additional factor to sound level (in dBA) and duration, having a negative view of the offending stimulus may be another tertiary culprit, at least for TTS.
In part 3 of this blog series, we will touch on some of the caveats or study limitations inherent with these types of studies.