A Question for the Decibel Specialists: Impulse Peak Decibel vs Max Decibel in Power Tools

Discussion in 'Support' started by Rust, Nov 28, 2020.

    1. Rust

      Rust Member

      Tinnitus Since:
      (2008 initially) 2015 as I know it today
      Cause of Tinnitus:
      Initially stress, but noise exposure made it worse
      Hi all,

      I use the SoundMeter X app for measuring decibels on my iPhone, and I've been getting a bit confused about Peak and Max decibel levels.

      After much research I purchased an electric nail gun (http://service.dewalt.co.uk/DEWALT/GB/en-GB/Product/ProductDetail?id=9915) for DIY work. The spec sheet states a sound pressure LpA of 84 dB, and an LwA Acoustic Power of 95 dB.

      Given sound pressure LpA means the decibel reading of the tool at the operator's ear, and that the reading is 84 dB, I figured that with double hearing protection I was well within comfortable dB limits.

      I fired some test shots using the nail gun with my iPhone positioned the same distance from my ear as the electric nail gun, and the max dB rating was coming out at about 93 dB Max when firing actual nails. I thought this wasn't too bad - still higher than the specified 84 dB, but not bad given I would use double ear protection.

      HOWEVER, I then noticed that the decibel app was stating a PEAK decibel rating of 120 dB. I have read into this, and it seems that the Max rating is only an average over a very short period of time (i.e. 1 second). Conversely though, a Peak reading is the maximum decibel level spike in any period of time.

      The nail gun didn't sound 120 dB, even with my ear protection. It was not uncomfortable, and about 93 dB with ear protection sounded about right.

      I then did a test. I recorded my drill consistently for 10 seconds, using the same sound meter iPhone app. It came out 88 dB max - only 1 dB different to the manufacturer's stated 89 dB rating. However, the Peak dB of the drill was 100 dB! This makes me think the Peak rating is not a proper representation of the sound level we are exposed to. The drill was a constant noise with no spikes.

      I then tested running my water tap - a constant 65 dB. Guess what, the Peak was about 80 dB. How??!! My tap is definitely not 80 dB!

      It seems the Peak is always higher, even if it is a constant noise, and not an impulse noise.

      My main concern is that I won't be able to continue using this nail gun if the peak truly is 120 dB. For me that's too much, even with ear protection. I am skeptical however.

      My question: Inimpulse noises (like nail guns), is the Peak decibel the only reading that's important, or can we trust the fast rated Max decibel rating?

      What noise will truly hurt our ears?

      Thank you!
    2. Michael Leigh

      Michael Leigh Member Benefactor Hall of Fame

      Brighton, UK
      Tinnitus Since:
      April /1996
      Cause of Tinnitus:
      Noise induced
      HI @Rust

      I know you have asked a specific question about your nail gun which others on the forum maybe able to help.

      You have had noise induced tinnitus for quite a while, have you seen an Audiologist that specialises in tinnitus and hyperacusis management? This is what I feel you need. I understand the reasons for using a sound level app and going to the lengths you have in order to protect yourself from loud noise and to using a nail gun in relative safety without making the tinnitus worse.

      However, it is my belief, sound level meters often make matters worse as one becomes more reliant upon them as a source of reference. A person tends to focus more on the tinnitus, hyperacusis if it is present and ultimately installing and reinforcing panic, fear and negative thinking. Unfortunately one can find themselves in a vortex of confusion and discontent if they are not careful.

      I stopped using dedicated sound level meter and sound apps a long time ago for the above reasons and began feeling a lot better and more positive about life. Please consider my suggestions and stop using sound apps and seek treatment with an Audiologist specialises in tinnitus and hyperacusis management. You can try self help by reading my thread: Hyperacusis, As I See It.

      All the best
    3. Ed209

      Ed209 Member Podcast Patron Benefactor Ambassador Hall of Fame

      Tinnitus Since:
      LwA is the amount of energy being given off and the LpA is the sound pressure level.

      When measuring sound, there is a timed window depending upon what you’re measuring, and some devices are not capable of accurately capturing fast impulsive sounds in the high millisecond range. Continuous sound is measured with a much wider window that averages the peaks. To truly capture impulsive sounds accurately you need good equipment like a type 1 meter.

      The peaks you are talking about are generally nothing to worry about. All the sound around us has peaks, we just don’t know about them, or care about them. The most important aspect, or risk, is the energy associated with the peaks and how long they last for. Gunfire, for example, carries a risk as the total energy in the waveform is high.

      For continuous noise, the important number is the LAeq, or the averaged equivalent A-weighted dosage of sound you’re exposed to over a given time period.

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