This is the second in a series of articles called “More Than You Wanted to Know About Sound Systems.“
Your Ears Respond Differently as Volume Increases
Your ears have a usable range of 120 dB SPL. This is a graph of frequency vs SPL showing how the response of your ears change as volume increases. What does this tell us? You need more low end (bass) to play quieter and still have a full sound. Remember the “LOUDNESS” button on old stereos? They were designed to compensate for this effect.
This graph is hard to decipher. It was done by audiologists testing average hearing. The two lines are just the new method and old method compared. Also no testing was done above 14k Hz. If you could hear above 14k Hz they couldn’t sell a hearing aid.
As SPL increases, a muscle tightens in your ear to limit movement of the eardrum.
Two things can be learned:
- Sudden loud sound can be very damaging because muscles are not pre-tightened.
- The 120dB of range is not available all at same time.
With 80 dB of background noise you have to listen closely to hear something in speakers at 50 dB. Also referred to as “LOST IN THE MIX.” Everything coming out of speakers should be heard or it’s just more noise.