Psychoacoustics

Psychoacoustic is scientific study of sound perception. 

Not like machines or techniques, when a person hears something, 

it is not just waves or sounds going to ear to brain,

 but within the ear it is transformed into neural action potentials. 

These neural action potentials then travel to the brain. in the field of audio processing,

 they use this fact that both ear and the brain are involved 

in a person's listening experience. 

Techniques like MP3 or Telephone networks and audio reduction systems 

are the examples applied with psychoacoustics.

What was interesting about psychoacoustics

that they study subjective perceptions about sounds. 

Given one example of sounds, 

Everyone receive different perceptions 

because of where they surrounded and their feelings.

Sound is not technical or same to all people.

For example, 

It becomes louder when people sip their coffees at the library than on the street. 

It becomes louder of car clarkson in the middle of the night than at the afternoon. 

There are several effects related to psychoacoustics

Masking effect

cocktail party effect

doppler effect

hass effect

loudness effect

pitch effect

And

There are many fields using psychoacoustics 

such as in the software industries.