In addition to the comments made in reply to your question, something else to consider is that all loudspeakers and ears are different.
If you want to faithfully reproduce the original sound, you might need to tweak the audio using an equaliser.
If you have tiny speakers for example, you might need to amplify the lower frequencies, the bass, and suppress some of the higher frequencies, the treble, to compensate.
Deafness is not the only thing that happens to ears. For example, my ears have trouble hearing much above 2 kHz, so I often need to suppress the bass and increase the treble to make stuff properly audible, since otherwise the bass overwhelms everything and I can't understand what a person is saying.
Finally, sound is based on vibration of air. Slow vibration makes low sounds, fast vibration makes high sounds. The speed at which the vibration happens is expressed as a frequency and the name for it is Hertz, or Hz. 1 Hz is once per second. 10 Hz, is ten times per second. 2 kHz is 2000 times per second.