@amirm -- So do you ever sleep?
Acoustics is not my day job so others can do a much better job, but here is what I have said over the years.
For sounds in the midrange when listing to music or movies:
- +1 dB change is barely detectable to most people and is a 1.26x increase in power.
- +3 dB is about what most of us do when asked to "make it a little louder" and is a 2x increase in power.
- +6 dB is a "big" change and requires 4x the power.
- +10 dB sounds twice as loud and requires 10x the power.
Equal-loudness curves:
https://en.wikipedia.org/wiki/Equal-loudness_contour These show how much louder (or softer) sounds at different frequencies need to be to sound as loud as a 1 kHz tone. The dip around 3 kHz is where we are most sensitive; roughly the frequency of a baby's cry. The original Fletcher-Munson curves were revised in the 1950's by Robinson and Dadson. The latter mainly revised the bass curves upwards and are the essence of the current ISO standard.
Years ago (no, I don't have the reference; it is in the black hole storage in the basement) a study demonstrated 17 dB peak-to-average power ratio for music. IIRC it was mostly classical'ish. Note 17 dB is a factor of 50x in power. If your average listening level is 1 W, you need 50 W to prevent most clipping. I have read reports of 20 dB in modern music (assuming not squashed by the loudness wars) and 30 dB in movies. Most of the time the loudest sounds will be big cymbal and drum crashes, explosions, gun shots, and the like so clipping may well go unnoticed.
Online calculator for SPL with your speakers and room:
_Peak SPL Calculator These calculators are only a rough estimate since speaker sensitivity and room absorption varies over frequency (among other things).
It is important to note that OSHA standards, often quoted for how loud it takes for hearing loss, do NOT target audiophiles. They are designed so the average person can hold intelligible conversation without shouting, not catch fine nuances in music. If you want to retain good hearing, take the OSHA guidance as upper limits requiring plenty of margin.
FWIWFM - Don
