WHY are mammals鈥� inner ears coiled like a snail shell? One popular theory is that it simply allows the long organ to be packed into a small space, but now Daphne Manoussaki at Vanderbilt University in Nashville, Tennessee, and colleagues have come up with a different answer.
They say the shape improves hearing by amplifying sound vibrations, particularly for low frequencies (Physical Review Letters, DOI: 10.1103/PhysRevLett.96.088701). 鈥淭he increasing winding along the tube causes the energy from sound waves to build up towards the outer wall of the spiral,鈥� Manoussaki says.
The researchers liken this to the 鈥渨hispering gallery鈥� effect in St Paul鈥檚 Cathedral in London, where the gallery鈥檚 circular shape allows someone whispering against its wall to be heard on the opposite side.
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