I’m lying in bed. It’s nearly midnight and I’m trying to get to sleep. The street where I live is normally very quiet (apart from gangs of herring gulls fighting on the roofs) but on this occasion I can hear a lorry outside my house. It has its engine running but it doesn’t drive off, and after a few minutes I start to wonder why it’s not moving. Why is it just sitting there, and so late at night? The noise begins to feel ominous, unsettling. It’s becoming more and more of a physical presence in the bedroom and finally I clamber out of bed and go to the window to peer out. There is no lorry, just the usual ranks of parked cars and none of them has their engines running. They’re all still and silent.
What I’m hearing is actually a sound manufactured in my own ears, I’m suffering from tinnitus. Tinnitus occurs when the ears detect apparent noise where there is in fact just silence. I say ‘just’ silence but that feels like an elusive and unattainable state for me. My constant tinnitus means that I never experience silence. I am always hearing, even when I don’t want to. My body creates a sensation and then tries to imagine something in the external world that can be associated with it.
In her book ‘Purity and Danger’ the anthropologist Mary Douglas describes dirt as ‘matter out of place’, and it disgusts us or makes us uneasy because it shouldn’t be there. Similarly, the sounds created by tinnitus shouldn’t exist. They are uncanny noises in a place where there is really silence.
This sense of something gone wrong is heightened by the fact that sound is less directional than vision, it’s more difficult to link sound to its source because sound waves are capable of changing direction through the process of diffraction. When we hear a sound we have to calculate where it’s coming from, and we’re so accustomed to doing this calculation that we also do it when the sound is being created within us.