Excerpts from Chapter 8, A Bridge of Sound:
“In the late 1940s Tomatis continued to attack the conventional wisdom that the larynx is the key organ for singing. He showed that contrary to conventional wisdom, singers with bass voices did not have larger larynxes than those with higher voices …. He summed it up by saying provocatively, ‘One sings with one’s ear,’ a statement that caused much laughter.
“Arguably his most important discovery was that the ear is not a passive organ but has the equivalent of a zoom lens that allows it to focus on particular noises and filter others out. When people first walk into a party they hear a jumble of noises, until they zoom in on particular conversations, each occurring at slightly different sound frequencies. Once a person forms a conscious intention to listen to a particular conversation, the listening, from a physiological perspective, is never passive, because two muscles within the middle ear allow it to focus on particular frequencies and protect it from sudden loud sounds ….
“These muscles of the middle ear, which tune in on speech, are regulated by the brain. As studies by the neuroscientist Jonathan Fritz and his colleagues from the University of Maryland show, when particular frequencies carry important information … the brain map areas for those frequencies in the auditory cortex grow within minutes, to better tune in on them …. Thus the auditory zoom has a plastic component.
“The first of the two muscles is the stapedius. When it tenses, it increases the perception and discrimination of the medium-high-frequency sounds of language, while muting the lower tones that overwhelm higher frequencies, allowing the listener to extract speech sounds from the environment. The second muscle is the tensor tympani, which modifies the tension of the tympanic membrane (the eardrum). It complements the stapedius, and when it tenses, it decreases the perception of low-frequency sounds in background noise. Both of these middle ear muscles contract when we speak, so that we don’t injure our ears with the sound of our own voices. This happens not only with opera singers; a child screaming is about as loud as a passing train. “