Why do some sounds sound nasty and some sweet? What makes something sound distant? How can something sound heavy? What makes our ears and brains zing when we listen to music on earphones or headphones?
Despite its big title, psychoacoustics is simply the study of how we perceive and react to sound. Understanding of psychacoustics is behind many media tech systems such as MP3 files, stereo field and bass enhancement controls on media players and even the tone of police sirens.
By understanding how we perceive sounds the techies have built systems that fool the brain into perceiving sound in a different way.
Singers have been doing this for a long time. A strongly sung voice may often sound effortful... in a good way: energetic and decisive. But how it feels to the singer is usually much different to the way the listener hears it... causing many untrained singers to 'push' for the intense notes, rather than allowing them to build and be naturally strong through resonance.