Go to any audio Bootcamp or introduction to audio class and one trick question that comes up is: "What is psychoacoustics?" Many people think that they know the answer right off the bat by just looking at the word and comparing it to what they know. I can probably win money if I bet someone that one of the answers will be "it's how the sound makes you feel". Honestly, it would be the easiest $5 I ever made. So far I haven't heard a single person who wasn't an audio professional get the answer right. So what is the correct answer? Why thank you for asking person who is not asking.
The term psychoacoustics actually means the way our brain perceives sound. Imagine the scenario you are chatting with your friend at your apartment complex and near the next building over they are doing yard work. Lawn mowing or using a leaf blower, you know, that sort of stuff that they do early on the weekends when you try to sleep in. If they were a couple buildings down you would still hear the noise that the machines make but you can still hear your friend okay. If the yard work was being done on the next building over or next to you, then every time they fired up the lawnmower or leaf blower, you would have a hard time hearing your friend talk because the machines are going to be louder then what your friend's voice will be; unless he starts yelling. This is called masking. It is where one sound or sounds are louder than other sounds that prevent you from hearing the sounds that are quieter (like your friend's voice). This is but one of the few elements that the study of psychoacoustics covers. The main 2 elements are
- Limit of High Frequency the human ear can hear
- The Absolute Threshold of Hearing (the quietest pure tone a person can hear unaided)
This is but a small example of a much much larger study in these phenomenas and would require much more blog posts to fulling explain things. If you are curious about finding out more, then take a look at Designing Sounds Youtube video. It's less then an hour and 1/2 but it does give a good primer on psychoacoustics.