Technology

Fuzzy Logic: Getting an earful of yourself

Question: Why does our own voice sound different?

Seeing a glimpse of ourselves, or hearing our own voice can be unsettling. The hair out of place, the midriff bulge, and our squeaky voice are not what we imagine. The best response is to say it's only psychological, it doesn't matter, but we are social animals, and much of our success in life is the way we project to others.

When you hear your recorded voice – as on an answering machine – it sounds higher pitched because it takes a longer ...
When you hear your recorded voice – as on an answering machine – it sounds higher pitched because it takes a longer route to the cochlear. 

Researchers studied the relationship voice of 792 male CEOs, the size of their company, and their earnings. A deeper voice was associated with the size of the company, and therefore their earnings.

When Margaret Thatcher entered politics, she was perceived as having a shrill voice, and to win office, she needed to change. One change that people noticed is how she lowered her pitch. One example shows it dropped by 46Hz.

When we hear another person's voice, the sound is carried through the air, into the outer ear, and then via the middle ear into the cochlear. Sound that goes via that route is extensively modified at each step along the way. The outer ear selectively amplifies certain portions, as does the ear canal. Incoming sounds at pitch – between 2kHz and 5Hz (at the top end of the piano keyboard) are doubled.

When you speak, your whole body resonates, especially the air cavities through your chest and throat. Sound is transmitted directly into the cochlear through the bones in your skull. Changes in the sounds that would occur in the outer and middle ear are bypassed, so what you hear are the deeper tones.

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When you hear your recorded voice, it sounds higher pitched.

You can get a similar effect hearing another voice underwater. In this case, the outer ear is surrounded by water, and the usual amplification is ineffective. What you then hear are the sounds transmitted through bone into the cochlear.

A less obvious reason is a remarkable pair of muscles. They're impressive, but you'll never see these shown off on tanned bodies at the beach. The tensor tympani and the stapedius are two of the smallest muscles connected to the two smallest bones in your body. Their job is to dampen the middle ear so you don't deafen yourself when chewing or talking.

When you talk the acoustic reflex is activated. That doesn't happen when you're listening to a recording ... unless you talk at the same time.

Rod Taylor is writing The Edge of Silence, a book about sound.

Response by: Rod Taylor, Fuzzy Logic

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