Why leaf-blowers leave your ears ringing
Noise Sensitive? Can't bear the sound of leaf blowers or machinery?
The complexity of the acoustic environment in our contemporary industrial world is that it is loaded with low frequency sounds our nervous system interprets as predators.
If you've experienced trauma, and particularly if you're in recovery, your physiological state is already highly-attuned to danger. So when your neighbour uses their leaf blower, or the street-sweeper truck whines at midnight, your highly-sensitive nervous system skyrockets into high tone, sympathetic arousal that makes it impossible for the sound to reach your middle ear bones to dampen your fear.
Instead of noise being mediated through your middle ear bones, the sound vibrates through your jawbone, and from your body's perspective, those vibrations signal the approach of a predator or a threat - possibly a real-life tiger in the form of a leaf blower coming to suck you up and spit you out.
All mammals have the unique characteristic of their middle ear bones 'detached' from their jawbone, which enables them to hear certain frequencies, especially above background noise. They will only hear particular frequencies if their body (biology) feels safe.
Those frequencies match the intonation in the human voice. Vocal prosidy has the power to change our physiological state - and in so doing, provide us (and our bodies) with the experience of safety. In a nutshell, the 'right' pitch of voice will make us feel safe.
Often - but not always - it is a perfect match to the intonation of the female voice (but think about the actors Alan Rickman and Richard Burton and you'll know this isn't just a female thing). Perfect prosidy is often the same pitch found in a mother's lullaby, or the melody in a symphony. Folk music is a great example, because even though the lyrics could be referring to horrible things, the musicians sing very melodically - and often smile while doing it. Smiling also activates the inner ear bones, which switches on the nerve that mediates social engagement (vagus nerve 10), which can only be turned on when we feel safe.
That's the power of vocal intonation to change physiological state.