Listening #60

By Art Dudley

December, 2007

I don't want a symphony orchestra in my room: That's crazy. I want their music, played with enough realism that I can hear how it's done.
My room is 12' wide by 19' long, with an 8' ceiling, and it's made of wood and Sheetrock. There's no way any sane person would want to sit there and hear the same loudness level they'd hear in a concert hall, in the presence of a full orchestra. Count me among them.

TABLE G-16 - PERMISSIBLE NOISE EXPOSURES (1)
______________________________________________________________
|
Duration per day, hours | Sound level dBA slow response
____________________________|_________________________________
|
8...........................| 90
6...........................| 92
4...........................| 95
3...........................| 97
2...........................| 100
1 1/2 ......................| 102
1...........................| 105
1/2 ........................| 110
1/4 or less................| 115
____________________________|________________________________
Footnote(1) When the daily noise exposure is composed of two or more periods of noise exposure of different levels, their combined effect should be considered, rather than the individual effect of each. If the sum of the following fractions: C(1)/T(1) + (2)/T(2) C(n)/T(n) exceeds unity, then, the mixed exposure should be considered to exceed the limit value. Cn indicates the total time of exposure at a specified noise level, and Tn indicates the total time of exposure permitted at that level. Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level.

Above are the OSHA thresholds based on exposures that will result in hearing loss.

I typically find that prolonged listening at 84 dB with peaks reaching 94 dB is enough in my small room to have plenty of "realism."

With classical music the correct listening level I am told is for you to be able to hear the quiet passages. I have fixed my volume control there and never change it no matter what music I listen to. However the since my family seem to think I still listen too loud, I measured my listening volume using the loudest music I have, via a RS Spl meter and was surprised to find that I never hit anything above 85dB. I have however noted that what is loud to me may not be loud enough or too loud for someone else. The right listening volume (safe if its below 90dB) is what you are comfortable with.

Quote:
Hmm....so, its safe to listen at that level for over 8 hours...really, wow.

OSHA considers it allowable. Safe is another question. Desirable is another question.

I think at 85 dB, it's plenty loud in a room at home for most the of the music I listen to. I occasionally need it louder for theater effects, but preference is the key. The kilowatt amp allows you to play the speaker so that the music peaks are not distorted, while the average level is still much lower. Say the peak is 10 times the average level. At 1000 watt peaks, the average level is 100 watts. If the speaker "speaks" at 88 dB for one watt at one meter, and you sit three meters away, the level at your listening position is closer to 80 dB for 1 watt from the amp. There is a rough rule of thumb that to sound twice as loud requires 10x the power (watts). So to sound only four times as loud you're running the amp at 100 watts average instead of 1 watt.

I hope I have remembered these relationships correctly; I'm sure other responders will correct me if I'm wrong.

Quote:
If the speaker "speaks" at 88 dB for one watt at one meter, and you sit three meters away, the level at your listening position is closer to 80 dB for 1 watt from the amp.

Probably that's true only if you're listening in mono through only one speaker while sitting outside.

http://myhometheater.homestead.com/splcalculator.html

Listening from my favorite spot I like it in the 80s somewhere. Sometimes in the 90s.