Question

Describe how sound is produced by humans ?

Answer 1

Sound is produced by the voice box or the larynx in humans. ... Two vocal cords are stretched across the voice box. When lungs force air, vocal cords vibrate produce sound. When the vocal cords are tight and thin, the type or quality of voice is different from that when they are loose and thick.

Answer 2

Why do humans have two ears, one on each side of the head? Providing
more than two auditory sensors could improve spatial perception and
redundancy against damage or disease. Having only two ears is probably
an accident of evolution. However, two ears are better than one, because
binaural hearing improves sampling of complex sound fields, helps to dis-
criminate between sounds coming from either side of the head and still
provides some redundancy. Differences in relative amplitude and time of
arrival between sounds arriving from either side help the central nervous
system to localise sources on the left or the right much faster and with
greater precision than would be possible with one ear alone. In fish ances-
tors living underwater, this function could have evolved from directional
sensitivity to vibration inputs coming from different directions. Directional
sensitivity confers a survival advantage from being able to quickly iden-
tify and then move away from, rather than towards, vibration that gener-
ates threats. Underwater predators additionally benefit from being able to
quickly calculate the difference between threats and prey, so as to be able
move either away from the threat or towards the prey, and thereby acquir-
ing additional auditory neural processing.
Binaural recordings require two microphones in positions representative
of the ears on a real head. Microphones can be put on a headband to record
exactly the same sounds as heard by the person wearing the microphones,
or they can be put on a dummy head, or simply spaced apart with either
a solid disc or nothing (i.e. air) between them. On a real head or on a rep-
resentative dummy head, the microphones should be capable of recording
the full range of interaural differences in amplitude and time of arrival
which would have been heard by a listener at the same position in space
and time. Simplified binaural systems using an intervening solid disc or air
gap between the two microphones reflect many, but not all, of the inte-
raural differences. The main technical defect of binaural systems is that
they cannot easily record the differential effects of head rotation and other
movements on the interaural differences which provide important cues in
real-life listening.
In real-life listening, if the head is fixed in position, it is difficult to tell
whether sounds are coming from the front or the back. In real life, rotating
the head helps listeners to resolve front-to-back and other directional ambi-
guities. Rotating the head when listening to binaural recordings using head-
phones has no effect on interaural differences. This encourages perceived
stereo images to collapse into the centre of the head. When listening to
binaural recordings, some listeners are better than others at disregarding or
ignoring conflicting head rotation cues, leading to a wide range of subjec-
tive impressions. Binaural recording systems have been advocated for noise
assessment and regulation purposes, on the premise that they are more