Hearing

Frequency

When young the range is 20 - 20.000 Hz.
The sensitivity varies with the frequency and is best between 1 kHz and 5 kHz.Your audio components might have a straight  frequency response, your ears don’t.

You can test the frequency response of your ears here: http://www.phys.unsw.edu.au/jw/hearing.html

Presbycusis

A progressive loss of the ability to hear high frequencies, which occurs as people get older.

 

Source: http://www.hearinglosshelp.com/articles/reverseslopeshort.htm

Some nice empirical evidence: http://www.hydrogenaudio.org/forums/index.php?showtopic=65398

Dynamic range

Sound is a variation in air pressure. We can detect a change of less than one billionth of standard atmospheric pressure. This is the lower threshold and corresponds to 0 decibels. Sound at 120/130 dB starts to hurt. Our dynamic range is 0 - 130 dB, a difference of 10¹³ =10.000.000.000.000. That's why a logarithmic scale is used.

Time difference

Sound coming from one direction will reach the ear furthest away later than the closer ear. We can discern approximately 1/500 second time lag.

Pitch

The frequency of a note. Very few people can tell the pitch of a isolated note.

In classical music the A is used to tune. In case of baroque music this is 415, classicism 430 en modern 440 Hz. If you have perfect pitch you have a problem!

 

Reading: http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html