BIO-TECH | Scientists unravel secret of human ears’ extreme sensitivity to pick up faint sounds
WASHINGTON — American scientists found that a gel membrane in the inner ear gave people extraordinary hearing sensitivity so that it could detect vibrations of the eardrum that move by less than the width of an atom.
The study published on Wednesday in the journal Physical Review Letters showed that the human ear’s ability to distinguish different frequencies of sound mainly depend on the behavior of a tiny gelatinous structure called the tectorial membrane.
The membrane, atop the tiny hairs that line the cochlea, is thinner than a hair. Those hairs are sensitive to different frequencies of sound and their tips are embedded in the gel membrane, according to the study.
Also, the membrane has minuscule pores that control the movement of water within the gel, a saturated sponge-like structure which you can squeeze the water out.
The researchers from Massachusetts Institute of Technology (MIT) found those pores with certain size and arrangement can affect how water moves back and forth in response to vibration.
The highest and lowest tones are less affected by the amplification made by the membrane but the middle ones are strongly amplified, according to the study.
The paper’s lead author Jonathan Sellon, professor of electrical engineering at MIT, said the structure moved as a liquid for middle frequencies but as a solid for high and low ones, tuned “just right to get the signal you need.”
The researchers said those findings could help devise ways to treat hearing impairment via medical interventions that alter the pores or the properties of the fluid in the membrane.