Even in a crowded room full of background noise, the human ear is remarkably adept at tuning in to a single voice a feat that has proved remarkably difficult for computers to match. A new analysis of the underlying mechanisms, conducted by researchers at MIT, has provided insights that could ultimately lead to better machine hearing, and perhaps to better hearing aids as well.
Our ears' selectivity, it turns out, arises from evolution's precise tuning of a tiny membrane, inside the inner ear, called the tectorial membrane. The viscosity of this membrane its firmness, or lack thereof depends on the size and distribution of tiny pores, just a few tens of nanometers wide. This, in turn, provides mechanical filtering that helps to sort out specific sounds.
The new findings are reported in the Biophysical Journal by a team led by MIT graduate student Jonathan Sellon, and including research scientist Roozbeh Ghaffari, former graduate student Shirin Farrahi, and professor of electrical engineering Dennis Freeman. The team collaborated with biologist Guy Richardson of the University of Sussex.
In discriminating among competing sounds, the human ear is "extraordinary compared to conventional speech- and sound-recognition technologies," Freeman says. The exact reasons have remained elusive but the importance of the tectorial membrane, located inside the cochlea, or inner ear, has become clear in recent years, largely through the work of Freeman and his colleagues. Now it seems that a flawed assumption contributed to the longstanding difficulty in understanding the importance of this membrane.
Much of our ability to differentiate among sounds is frequency-based, Freeman says so researchers had "assumed that the better we could resolve frequency, the better we could hear." But this assumption turns out not always to be true.
In fact, Freeman and his co-authors previou
|Contact: Abby Abazorius|
Massachusetts Institute of Technology