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[size=10pt]Adding muffs over in-ears does not increase the attenuation NRR in an add-on fashion thus a 12dB set of generics and a 26dB set of muffs would not be 38 NRR.[/size]
Is that because of the logarithmic nature of the numbers used, the physics related to sound isolation, or some of both?
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Originally Posted by Aurisonics /img/forum/go_quote.gif
[size=10pt]I have done a lot of testing and validation of hearing protection devices both in-ear and over the ear for Military and Aerospace applications for many years. It always gets me stirred up when people throw numbers around on this stuff. Tone Seeker I'm not calling you out on this (quite the contrary) at all I just want us to begin to work together as a group to dispel some of the myths around NRR and dB etc when it comes to isolation numbers and hearing protection/conservation etc. [/size]
That's really encouraging to hear! I highly value deep expertise in this area.
I've had Tinnitus for around 17 years. I had the misfortune of receiving some bad advice early on; "Better wear earplugs because it's only going to get worse!" I was told. As a result I over protected and developed hyperacusis. It became so bad that I had to wear foamy earplugs just to walk outside in the city. Four adults talking along with a TV playing in an acoustically likely room would cause me discomfort. My loudness discomfort levels had diminished to 74dbA at certain frequencies, if I remember correctly. Needless to say, I had to come up with some very creative ways to continue playing electric guitar on stage.
Fortunately, I found a local audiologist who truly understood tinnitus / hyperacusis, and knew how to treat them. After two years of tinnitus retraining therapy my tinnitus was significantly reduced and my hyperacusis eliminated. That journey began four years ago and I no longer wear hearing protection, other than when I should. Fortunately, the venue I play in (church worship team) switched to an in-ear system a couple of years ago so stage levels are reasonable. I've discovered that I love the clarity of in-ears and the ability to create my own monitor mix.
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[size=10pt]I'm more than open to any questions on this stuff. I could talk for years on the subject of hearing protection/conservation devices in-ear and over-the-ear. [/size]
Because of my struggles with tinnitus / hyperacusis I've become much more aware of what is, and is not, potentially a safe listening environment. However, I know of only one manufacturer that provides an "SPL meter" to let you know if your in-ear listening level is potentially unsafe. They derive this based on the in-ear monitor's current draw and the know characteristics of their product.
Dale, can you offer any suggestions for how to ensure that we don't have our in-ears set too loud?
I find this difficult to do. Our brain seems to easily adapt to levels that may be unsafe, yet when we turn things down too far they become "dull" (i.e. we run into the non-linear frequency response of our ears - Fletcher-Munson). In my specific case I have to find the sweet spot to develop my guitar tones. Too quiet and they sound dull / lifeless, and I over-correct. Too loud and I put my hearing at risk.
I'd appreciate hearing any thoughts, strategies or (ideally) about any tools that might be available.
Terry.