Jim Lane/Alamy
What part, if any, do my ears or auditory system play when I generate a tune in my head? (continued)
Mike Follows
Sutton Coldfield, West Midlands, UK
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If you wake first and then decide to pee, broken sleep may be to blame. If the urge itself wakes you up, it’s the bladder
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Imagining a song is an example of a phantom perception – the conscious awareness of a sensory experience without an external stimulus. When you imagine a tune, many of the same regions of the brain (particularly the secondary auditory cortex in the superior temporal gyrus) activate as if you were actually hearing the sound, but without involving your ears. This capacity is shaped by a lifetime of listening. I imagine that at least some composers can hear the music they are creating before it is ever played.
While earworms – songs that replay in our heads – can be irritating, tinnitus is a far more unpleasant phantom perception: a ringing or buzzing sound that affects about 15 per cent of the population and can be continuous and debilitating for some.
Neuroscientist Linus Milinski and his team at the University of Oxford’s Sleep and Circadian Neuroscience Institute suspect that tinnitus is associated with poor sleep. They propose that the large, spontaneous waves of brain activity occurring during deep, non-rapid eye movement (non-REM) sleep might normally suppress the activity that gives rise to tinnitus. Their research may ultimately lead to better understanding – and possibly a cure.
We are highly sensitive to extremely quiet sounds, which suggests that our auditory system must amplify the incoming signal. Stochastic resonance is a phenomenon in which adding an optimal level of noise can amplify a weak signal, improving its detection or processing. I wonder whether tinnitus might be the noise our brains naturally introduce to enhance the signal – but that modern living disturbs our sleep to the extent that, in some people, this internal noise becomes audible.
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