A question about subwoofers and hearing loss.

Discussion in 'Archived Threads 2001-2004' started by Sheldon C, May 15, 2002.

  1. Sheldon C

    Sheldon C Second Unit

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    I was at a friends house listening to his new svs 16-46 pci last night and my ears started hurting a little bit. We were testing out all of the big bass dvd's (TS 2, Jurassic Park, TPM, Pearl Harbor etc.) and using the decibal meter to see how loud it was getting. During the peaks of massive bass the decibals reached between 105 and 110 which I believe is in the danger zone for hearing damage.

    Anyway, my question is are low freqencies not as damaging to our ears as other frequencies? If they are just as harmful then I need to rethink this hobby of mine. The problem is I really didn't think the volume was set really loud but like I said my ears were a little sore during my drive home.

    By the way, I loved how the sub sounded but it bugged me how you could hear bass from the sub during male voices. His receivers crossover is at 80 so supposedly this shouldn't be possible but it was very obvious and annoying. Since his mains are rated to 28 I wonder if he should try setting them to large.
     
  2. Ned

    Ned Supporting Actor

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    I have mine running on a 100hz cross-over and it has no male vocal "leakage". This is actually not possible if you connect it properly to the LFE, which only receives 0-120hz regardless of how you setup the other speakers (small/large). You may however be hearing too much 100-120hz bass, but not higher frequencies.

    Low frequencies are not damaging like the mid and high frequency ranges. If you're hitting those levels then the other speakers are getting up there in volume, so room acoustics and distortion could be factors.
     
  3. Sheldon C

    Sheldon C Second Unit

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    Thanks Ned - yeah I wonder if something is wrong with his receiver. He has the sub hooked up properly (kind of tough to screw that up with a powered sub).

    I hope your right about low frequencies not being as harmful, I would hate to think that any time the bass hits hard it's making me go deaf.
     
  4. Larry B

    Larry B Screenwriter

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    Ned:

     
  5. Walt N

    Walt N Second Unit

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    Be careful!
    David Clark--
    "Sound energy at any frequency will damage your hearing, the question is - are some frequency ranges more damaging than others? The jury is out on this one, but it is well known that the sensitivity of the ear varies with overall level and with frequency (the Fletcher-Munson curves). Generally speaking, we hear the upper mid bands louder than the other frequencies and we hear the sub-bass and highs less, meaning that the upper mids will hurt long before the bottom or top end. Therefore, if we control the upper mids in the mix, then we can achieve a very loud mix with punishing bottom and brilliant highs that appears painless - never mind that we are pouring all that energy into the hearing system. The bottom line - just because the bass doesn’t hurt as much, don’t discount it. It’s probably doing just as much damage to our hearing as the upper mid is."
    Full article: http://www.engineeringharmonics.com/papers/hearing1.htm
     
  6. John Garcia

    John Garcia Executive Producer

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    Turn it down...
     
  7. Mike Kao

    Mike Kao Second Unit

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    yea, it's incorrect to say that low frequencies are NOT damaging to your ears
     
  8. Frank_S

    Frank_S Supporting Actor

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  9. Steve_Ma

    Steve_Ma Second Unit

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    Agree with John and Frank. Make sure the system is calibrated and lighten up on the volume!

    On a side note:

    I also keep my sub crossed at 100hz (my AVR also has a VERY gradual slope). If I ever heard a male voice coming out of my sub, I think I'd c%$p my pants.

    I've read it's possible for some male voices to get below 100hz, but I have yet to hear a voice coming from my sub.

    --Steve
     
  10. Sheldon C

    Sheldon C Second Unit

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    To clarify about the male voice thing, it wasn't like the actual words were coming from the sub. However, there was a "hum" of bass coming from the sub that obviously corresponded with the words coming out of the center channel.
     
  11. Wayne A. Pflughaupt

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    Whether or not there is “leakage” into the sub from male voices depends on the crossover frequency, the slopes, and the actual program. I have mine set at 90Hz with steep 24dB/octave slopes and usually it’s fine. However, I do find that some TV shows have poorly EQd voice tracks with exaggerated bass in the male vocals – verified by the RTA hooked up to my system - that can indeed “bleed” through to the sub.

    It is important to remember that a crossover’s published specs are referenced to a flat signal, and that a crossover is not a “brick wall.” Actual frequency division is highly program dependent. Not to mention things like equalization can effectively “blow out” a crossover’s filter and “move” it’s functioning turnover frequency out an octave or more.

    Regards,

    Wayne A. Pflughaupt
     
  12. jeff lam

    jeff lam Screenwriter

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    I don't know about you guys but my ears don't hurt nearly as much with a 100dB 30hz tone as it does with a 100dB 1Khz tone.

    I thought the ears are not as sensitive to low tones as high tones. Isn't the table on hearing damage in the A-weighting scale? It makes sense that our ears could withstand louder low notes than louder mid or high tones.

    Not saying that low tone's can't damage hearing as I know they can, but I'm guessing that you will do more damage to your ears with mid-higher tones than low tones at the same amplitude.

    Does anyone know for sure if this is true?
     
  13. Andrew_Ballew

    Andrew_Ballew Second Unit

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    It is very possible and more than likely for a male voice to fall below your crossover and end up in your subwoofer if he is singing. I am pretty sure that in the case above you were just referring to speaking, which, yes, should not happen.

    BUT...

    The low end of the male singing voice, for most professional bassists about C , second octave from the bottom of the piano, is 65.406 hertz in the equal temperment system. A whole step up to D is 73.416 hertz, and finally a half-step up to Eb is 77.782 hertz, all below the THX crossover point of 80 hertz.

    As a matter of fact, an excellent example is found on the DTS CD of Boys to Men II. The final track, Yesterday, has the bass vocalist bottoming on the above mentioned Eb, causing a bass balance riot if your subwoofer is not properly EQ'd.

    Andrew B.
     
  14. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    If I remember correctly from biology, our ear drum is like a "passive radiator" to transmit vibrations to those tiny bones and nautilus structure.

    Lower notes can cause the ear drum to move more (xmax) while higher notes cause the membrane to move more rapidly.

    I can see that too much of either can cause damage.. Since too fast can be damaging to the membrane and too low can pop it. Or both cases can desensitize the hearing leading to loss.

    So the higher notes go further in the canal while the lower notes don't. Then tiny hairs lining the walls of the canal get moved by those vibrations and depending on their location in the canal, your brain perceives the movement as different sounds. (memory is a bit hazy)

    Sound regardless of frequency will cause damage if in excess. The only thing different about the frequencies is the rate at which it moves the ear drum. I'd conclude higher frequencies are more damaging if our ear drums can't withstand faster vibrations than it can slower vibrations.

    I can only assume higher frequencies are more damaging because high notes move the ear drum much faster than low notes.
     
  15. Allan F

    Allan F Agent

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    I'm not going to answer this question thoroughly because it would take a short novel to do so. Walt provided a very good link explaining (in ample detail) the operations involved in your Auditory system. In short: If it hurts, TURN IT DOWN. If your ears are ringing (tinnitus) after exposure, TURN IT DOWN. If your hearing actually shifts for any period of time following exposure, DON'T EVER DO THAT AGAIN.

    Once the cilia of the outer or inner hair cells within the human cochlea (our primary organ of hearing) have broken off -- THEY ARE GONE.

    To answer that question. Technically the the higher frequencies are potentially more damaging to your hearing due to the location of the cilia that are stimulated by the higher frequency inputs. These hair cells are located closest to the oval window (the point of entry into the cochlea) and, as a result, get the full unattenuated effect of the loud music. This does not mean, however, that low frequency outputs are not damaging! The interesting thing about Noise induced hearing loss is that your hearing is genuinely affected well before the problem shows up on a hearing test. We lose our frequency selectivity first. So it becomes increasingly difficult to distinguish those subtle differences in sounds. There is lots of good info out there in Audiology texts and on Medline if you are interested to learn more.

    Allan

    Clinical Audiologist.
     
  16. Sheldon C

    Sheldon C Second Unit

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    Hey Allan - I have had a slight "ringing" sound in my ears (more like inside my head) when I am in a totally quiet envirnment or when I put my fingers over my ears for as long as I can remember; this includes long before I listened to really loud music or loud movies.

    What I am wondering is, is it possible to have a slight ringing sound and it not be tinnitus? Like I said, it's always been there even when I was a kid and had no access to loud music.
     
  17. Allan F

    Allan F Agent

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    Sheldon,

    Theoretically, any sound that you hear (high pitch or low pitch) is tinnitus. Although, the presence of tinnitus does not necessarily mean that you have hearing loss. It's just a symptom typically associated with HL. Lots of people, including myself, have tinnitus. Most people, along those lines, are more aware of it in quite.

    Allan
     
  18. Sheldon C

    Sheldon C Second Unit

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    Thanks a lot for the info Allen. (I feel better knowing that it's pretty common).
     
  19. Dustin B

    Dustin B Producer

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    Allan, could you elaborate a little more on what you mean by your hearing shifting.

    I notice that if I'm in a quiet environment for a period of time (lets say sleeping overnight) when I wake up in the morning, if I go to watch TV I set the volume significantly lower than I will in the afternoon or evening (and at this point it is by no means loud, always under 80dB on the meter) after I've been exposed to sound for a while.

    I hope this doesn't consitute a shift.

    And from your knowledge what are your feelings on listening at reference levels (peaks of 105dB from each channel and 115dB from the LFE channel, most of the time spend in the 75-85dB range), 5dB below reference and 10dB below reference.
     
  20. Westly T

    Westly T Second Unit

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    I could be completely off base here, let me know:

    Doesn't exposure to certain frequencies tend to cause more damage to your hearing of those frequencies? So if you listened to excessive levels of bass, you would loose more of your ability to hear those bass frequencies then higher frequencies? I do understand it would cause some damage to your hearing in general, but I thought it would cause significantly more damage to you’re hearing of the frequency causing the damage. If this were true, a person who listens to loud mid-range would have more problems with day-to-day life then someone who listens to loud bass. This is because we rely much more heavily on our mid range hearing (Voice, common noises that need our attention) then we do on low frequency sounds.
     

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