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What do you use to measure sound levels?

Discussion in 'Sound Science' started by gsilver, Aug 18, 2010.
  1. gsilver
    I'm interested in figuring out the volumes I set my headphones out as to not damage my hearing.
    I bought a Scosche SPL1000 sound level meter, and I'm not having any luck with it. I can set the headphones to levels far exceeding what I would listen to, put one end of the meter in one cup, and the end with the sensor in the other, and it will still only read in the mid-60s. 
    I also tried it with my (crappy) computer speakers, playing a song while setting the volume fairly high (and IMO, loud), and the meter read about 32.6 decibels... the same levels it reports when I'm not playing anything at all. If I set the volume all the way up, it'll go as high as 70.
    I don't need a fancy one, just something with ballpark accuracy.
  2. Ham Sandwich
    I checked the Scosche web site and found a FAQ (in PDF form) that gives the specs
    From the FAQ:
    The SPL1000 is a C-weighted sound pressure measuring device designed for recreational use
    Measurable frequency range: 50Hz - 5000Hz
    Measurable decibel range: 60db - 130db
    Measurements that are over or below its decibel range will be significantly less accurate
    C-weighting is fine, and is actually the weighting you generally want for measuring music.
    It might just not be a good SPL meter.  Especially if it won't even measure expected high levels from your speakers.  The specs for the meter are not good.  C-weighting should cover more than just the 50Hz-5000Hz range.
    When measuring headphones you should make a cardboard disc with a hole in the center to stick the SPL microphone through.  Use the cardboard disc to seal the headphone cup, put the SPL meter through the hole and measure.
    I've been using an American Recorder SPL-8810 that was $70 at the local Guitar Center store.  The RadioShack SPL meters also do fine and cost a little less.  I like the SPL-8810 because it only has two measurement ranges (Low 30-100db and High 60-130db).  The RadioShack meters have 7 ranges of about 20db each which means more twiddling to select the right range for what you are measuring.
  3. ford2
    I use the Realistic analogue meter as do many here (Tandy/Radio Shack).
    Excellent meter at a very good price.
  4. GreatDane Contributor
    Here are my old pics of what Ham Sandwich describes.
    peaceful1 likes this.
  5. Ham Sandwich
    This is what I rigged up for my SPL meter:
    The clear disc is a protector disc that you get when you buy a spindle of CD or DVD discs.  The center hole of the CD disc is actually a little larger than the mic so I glued on a rubber washer that fits the mic more snugly (the diameter of the mic is approx 1/2 inch).  It works and the clear disc is nice because you can see in to see where the mic is positioned.
  6. GreatDane Contributor
    Great idea! Nicely done HS. Much better than the crude cardboard style.
  7. jcx
    if you can measure drive voltage you can use the manufacturer's sensitivity number and a little calculation  - spec value of undamaged headphone is likey good to 1-2 dB
  8. Ham Sandwich

    And thanks to you and Skylab for showing me how to go about measuring the SPL of my headphones.  It's easy once you see how it's done.
    The SPL meter is such a useful tool.  I'm very inconsistent at and very poor at judging volume level by ear.  The SPL meter is the only way to know and to be consistent.  Sometimes I'll check the SPL and find I was listening quite a bit louder than I thought.
    For anyone concerned about doing hearing damage due to loud listening you absolutely need an SPL meter, especially if you like it loud.  It is soooo easy to bump the AC/DC to over 90 dB without realizing it.  I don't always like it loud, but sometimes it just happens.  Depends on mood and what I've been listening to previously.
  9. gsilver
    I don't necessarily listen loud, but my ears are prone to ringing when exposed to noise (the air conditioner of all things is loud enough to cause it), so I just need to be extra-careful.
    The SPL-8810 looks pretty good, and I found it at a good price.
    Thanks for the cardboard trick. A minute with the utility knife and I was able to cut one for the Scosche (which, of course, still read 32 decibels, even when I turned the volume up far beyond what I would listen to... I'm mailing it back on Monday).
  10. GreatDane Contributor

    I can relate. I bought my SPL meter about 8~9 years ago to calibrate a 6.1 HT system. I thought I had guessed the levels fairly close but I was way off. I had just gotten back into HP listening at the time also but it wasn't until after joining Head-Fi that I tried it with my HP.
    I sit just 5 feet from my speakers and listen usually no louder than 80 but with cans I can get carried away into 90+ too easily. I limit myself to very few tracks in crazy land.[​IMG]
  11. Happy Camper
    My headphone levels average 60-70 db on a 701 for concentrated listening. 10-15 db less for reading, surfing. Glad I don't have a way to check my IEMs on the mower. I might be over the speed limit there.
  12. TheAttorney
    Ham Sandwich, your clear disc looks really good. Think I'll have to replace my scrappy bit of cardboard now.
    I have the same SPL meter as you and am very pleased with it. I think the name is different in each country.
    It's got digital readout, A & C weighting, fast and slow, only 2 ranges, and two very useful options: backlight and max reading hold.
    It would be even better if it had just one range, but maybe that's not technically possible. Still the lower range of 30-100db is enough for most purposes. Having to fiddle with the old radioshack's 7 ranges would drive me up the wall.
  13. gsilver
    I got the sound meter today, and it seems to work fine. Regular speech measures within the expected levels, and turning my headphones way up (well, not too far up...), they read at ~90-100 decibels. Turning to levels I would listen to them at... 50-60? Seems a bit on the low side.
  14. GreatDane Contributor

     50 is really too low for me for normal listening sessions. I use IEMs to sleep, mainly as earplugs and listen  at very, very low volume. My normal level is 65~70 with full size cans.I don't often exceed 85, which is very loud.
  15. TheAttorney
    50db does seem rather low as a listening level. But comparing numbers is useless without common parameters:
    The difference in result is huge between a "C weighted, fast (peak), with plastic/cardboard disc thingy"  and an "A weighted. slow (average), without disc thingy".
    In my case, I was quite pleased that my normal/loud listening rarely went above 75dbA, peak, with disc.

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