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db Level and Hearing Problems

Discussion in 'Archived Threads 2001-2004' started by Norman L, May 5, 2002.

  1. Norman L

    Norman L Well-Known Member

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    I have had my reference level at 85db and have been listening 10db below reference. The peaks have been 20db to 30db above (95db to 105db). After watching Saving Private Ryan with the long ending chapter my ears were bothing me.

    If reference is set to 75db and volume is set 10db below reference on my receiver then peaks on the mains would be 85db and peaks on the LFE would be 95db. Is this a saffer setting to prevent against hearing problems or TINNITUS.
     
  2. Dustin B

    Dustin B Well-Known Member

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    I'll assume you are using Avia to set the reference level.

    My reading has told me that if you watched one or two movies a night at reference level no hearing damage would result. It might, however if you watched SPR (few movies have such long intense action sequences) twice a night ever night for a couple months.

    The frequencies of human speech are the ones most likely to cause damage. If you put the meter on the A weighting scale you are only using those frequencies to determine the spl level. Generally the A scale reads 5-15dB below what you get on the C scale. Some federal agency for work place hazards says it takes 8 hours a day at 90dB on an A scale to cause permenant damage. 2 hours a day at 100dB, 1 hour at 110dB, 20 min at 120dB.

    I prefer to listen to DD discs at 5-10dB under reference. I usually listen to DTS tracks at 3-5dB under that as I find the DTS discs louder.

    My system is not capable of doing full reference level cleanly. In my room my sub can come damn close, but my amp and speakers can't. 5dB under reference is the limit of my systems clean output. It could be you are pushing your system past it's limits and the distortion is what is bothering you.

    What speakers and amp are you using (including sub and what speakers are being run as small)? How big is your room? How far are you sitting from your mains?
     
  3. Phil Iturralde

    Phil Iturralde Well-Known Member

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  4. Ned

    Ned Well-Known Member

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    I've read that the very deep bass doesn't cause any hearing loss and that's where a lot of the SPL comes from in movies. That said, I'm 28 and I can only hear up to 16khz now [​IMG]
     
  5. Norman L

    Norman L Well-Known Member

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    Dustin & Phil

    ""What speakers and amp are you using (including sub and what speakers are being run as small)? How big is your room? How far are you sitting from your mains? ""

    Thanks for your response, Denon 2802, JBL S-Center, S38 mains, Sonance surrounds, SVS 25-31 Sub. The S-38 are at small with an 80 crossover.

    No other movie had bothered me except SPR.

    Room 18 x 13 open to other rooms on one side, catheral ceiling, and I am 16 feet from the mains but 5 feet from the sub.

    If reference is set to 75db and volume is set 10db below reference on my receiver then peaks on the mains would be 85db and peaks on the LFE would be 95db is that better?

    Thank for the advise on DTS.
     
  6. Phil Iturralde

    Phil Iturralde Well-Known Member

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  7. Dustin B

    Dustin B Well-Known Member

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    Well heres a basic run down.

    The S38 has a 89dB/W/m sensitivity. when you are 16' from them you could expect a 9-12dB loss. So lets say it is 9dB to be generous. Your starting sensitivity will then be 80dB/W/m.

    So:

    W - dB

    1 - 80

    2 - 83

    4 - 86

    8 - 89

    16 - 92

    32 - 95

    64 - 98

    128 - 101

    So in reality the loudest your system can go cleanly is just under 5dB under reference.

    I just replaced my Klipsch with JBL Studio series (S38; I'll hopefully get the S-Center and S26 tomorrow) and am using an Onkyo 575 (a little less power than the 2802). My sub is a chunk more capable than yours and I sit a little closer and have lower ceilings so 5dB under reference with the sub a little hot is the loudest I'll ever run my system.

    Reference is just a known guide line. If it's louder than you are comfortable with turn it down. I'd recommend calibrating at 75dB (as you said with the exception of SPR this level didn't bother you) with the Avia disc. Then if the movie is too loud, turn it down a bit (ie DTS SPR). The important part is that all your speakers are level matched, what level they are matched to is not that important.
     
  8. Phil Iturralde

    Phil Iturralde Well-Known Member

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    This SPL Calculator by C.M.Collins is excellent in get an idea what your SPL will be at your listening postion.
    I find that. @ -10 below REF Level, I have no problems reaching 105-106 dB+ @ my listening position pretty easily (9' from Center - 20' x 30' w/10' high vaulted ceiling , 20' x 20' is solid cement foundation w/oak square flooring and my HT/family back wall is 20' away from the front wall w/14' opening into the kitchen.). Those 105-106 dB+ SPLs are usually the fast-peak, sub-sonic LFE blockbuster type explosions like in Tomorrow Never Dies / SE, ID-4, U-571 DVDs., and some DVDs are recorded hotter vs. others, just like Music CDs.
    Phil
     
  9. Dustin B

    Dustin B Well-Known Member

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    Great link, it has the actual table I was talking about. My memory was close but not quite there.

    The only thing I don't aggree with him is his last statements about dialog volume. When I had my system at 5dB under reference with the sub 2-4dB hot I measured peaks of just over 110dB on a C scale (disc was TPM). On the A scale I'd just barely break 100dB in the same scene. Then on the A scale during dialog scenes the meter would be in the 70-80dB range.
     
  10. Norman L

    Norman L Well-Known Member

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    Dustin & Phil,

    Thanks again for your insight and the links.

    SPL ( Saving Private Ryan) was seen with a reference of 85db , my original settings, and seen about-10db from from reference with the LFE 3hot.

    That is way I want to change reference to 75db and watch -10db or -20 from a 85DB reference.

    Thanks to both of you. Health is the first priority.......
     

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