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Noise from Shaving

About 10 years ago I started using an electric shaver. An electric shaver is more convenient to use as it doesn’t require any soap, foam, or water. It is also almost impossible to cut yourself properly with an electric shaver which is a major benefit for anyone who’s not particularly alert in the morning. Generally my experience of electric shavers has been good, although the noise is quite annoying.

Recently a friend told me that an electric shaver is as noisy as a chain-saw. Given the inverse-square law and the fact that the shaver operates within 1cm of my ears that sounds plausible. So the risk of hearing loss is a great concern. Disposable ear plugs are very cheap and they can be used multiple times (they don’t get particularly dirty while shaving or get squashed in the short time needed to shave). So for a few weeks I’ve been using ear plugs while shaving which reduces the noise and presumable saves me from some hearing damage – although after 10 years of using electric shavers I may have already sustained some damage.

According to Cooper Safety their ear plugs reduce noise by 29dB, [1] I presume that the cheap ones I bought from Bunnings would be good for at least 15dB.

According to Better Hearing Sydney the noise from an electric shaver is typically around 90dB, less than the 100dB that is typical of a chain-saw [2]. So if my ear-plugs are good for 15dB then they would reduce the noise from a typical electric shaver to 75dB which is well below the 85dB that will cause hearing damage. Given that the noise from a typical shaver is only slightly above the damage threshold it seems that I might not need particularly good ear-plugs when shaving.

A quick scan of shaver reviews indicates that the amount of noise differs by brand and technology. The Hubpages review suggests that rotary shavers tend to make less noise than foil shavers [3], but I’m sure that it varies enough between brands that some rotary shavers are louder than the quietest foil shavers. It seems that the best thing to do when buying a new shaver would be to go to a specialised shaver shop (which has many models on offer) and get the staff to demonstrate them to determine which is the quietest. If a typical shaver produces 90dB then it seems likely that one of the more quiet models would produce less than 85dB.

Another item on my todo list is to buy a noise meter to measure the amount of noise produced in the places where I spend time. There are some Android apps to measure noise, I’m currently playing with the Smart Tools Co Sound Meter [4] which gives some interesting information. The documentation notes that phone microphones are limited to the typical volume and frequencies of human voice, so my Galaxy S3 can’t measure anything about 81dB. My wife’s Nexus 4 doesn’t seem to register anything above 74dB. Additionally there is some uncertainty about the accuracy of the microphone, there is a calibration feature but that requires another meter. Anyway the Sound Meter app suggests that my shaver (a Philips HQ7380/B) produces only 71dB at the closest possible range – and drops down to 67dB at the range I would use if I grew sideburns.

Conclusion

Getting a proper noise meter to protect one’s hearing seems like a good idea. An Android app for measuring noise is a good thing to have, even though it’s not going to be accurate it’s convenient and will give an indication.

When buying a shaver one should listen to all the options and choose a quiet one (I might have got a quiet one by luck).

Sideburns seem like a good idea if you value your hearing.

9 comments to Noise from Shaving

  • James T. Kirk

    I’ve been using an electric rotary shaver since I was a teenager and, as someone who takes great care protecting my hearing, I can’t believe I’ve never considered this before now. Thank your for raising it. If you end up buying a standalone sound meter, I’d love to hear your thoughts on it.

  • I personally stopped using my electric shaver when its battery died and when I discovered that: 1. it was not capable to function properly on wall power only and 2. its battery was just a standard AA accumulator with its label removed but that it was *soldered* inside the shaver! That kind of practice has a name: planned obsolescence. So I am now using soap, shave brush and a standard safety razor.

    Anyway, you should be aware that part of your shaver noise is carried to your internal ear through your skull, and that ear plugs will block nothing of that noise.

  • John Slee

    Hi Russell,

    I’ve tried quite a lot of earplugs for motorcycling purposes – with the aim of reducing the sound of disturbed air (typically caused by the motorcycle’s windscreen – ditching the windscreen tends to dramatically reduce the noise) hitting my helmet. The best (by far) that I’ve found for this purpose have been “Howard Leight Max”. You can buy them fairly cheaply in boxes of 100 or 200 pairs on eBay.

    These plugs have an NRR of 33 and I’ve found them to be extremely comfortable for long periods of motorcycling – 12+ hours a day of uninterrupted use presented no problems. Unlike a lot of other plugs I’d tried, they stay where you put them. Other plugs seem to gradually wiggle their way out, very annoying.

    I’m intrigued somewhat – I thought it was common for people on the Spectrum to really dislike things touching your ears – and I thought you’d written (if only in passing) about this previously. Do earplugs cause you the same issues?

    John

  • Patrick

    If the electric shaver were really as loud as a chain saw, don’t you think you would have recognized that already having such a loud sound in the morning?

    One reason why an electric shaver is not as loud might be, that the 1/r^2 law is only valid in the far-field, which is certainly not true if you shaver is 1 cm away from your ear.

  • beanbag

    NIOSH gives 8 hours (TWA) @ 85dB continuous (mostly non-cumulative). Must be quite a beard you have.
    Re-using earplugs does not strike me as particularly sanitary esp. given the environment it is kept in.

  • etbe

    Elessar: Good point about bone conduction. However I presume that some combination of both sources of noise (maybe even a harmonic) gives the bad result, so reducing one should still do some good.

    John: Yes in the past I’ve written about noise cancelling headphones for use on planes and other noisy environments. I wouldn’t want to wear ear-plugs for an international flight but for shaving it’s not such a problem for me. Among other things I’m not trying to read or sleep while shaving.

    Patrick: Given the different frequencies involved I don’t think I can properly compare them. Also it’s worth noting that lots of people sustain serious hearing damage through sound that they enjoy (IE loud concerts). So I think that the correct thing to do is to rely on machines to determine what’s safe.

    http://www.cdc.gov/niosh/topics/noise/

    beanbag: Hehe, good point. Above is the NIOSH web page, unfortunately they don’t seem to have a clear table of noise levels available (if you can find one then please give me the URL). Anyway I’ve seen a reference in passing to the 8 hours at 85dB which supports your point.

    However I’m not prepared to rely on the fact that it’s a short duration to protect my hearing. As Elessar points out there are other factors such as bone conduction to take into account.

    http://dsc.discovery.com/tv-shows/mythbusters/mythbusters-database/fecal-matter-on-toothbrush.htm

    Also I currently store my ear-plugs in my bedroom which seems more sanitary than my toothbrush which is stored in the bathroom. But then Mythbusters showed that other rooms get fecal bacteria…

  • John Slee

    As someone who suffers tinnitus I can easily understand being paranoid about it. Paranoia sure beats a ringing in your ears 24 hours a day!

  • Patrick

    etbe: Without question, it’s important to protect the ears from very loud sounds. And you are right, the human hearing adapts to the overall loudness level.

    Anyway, when you go to a rock concert, the first thing you notice (at least people who protected their ears quite well) is: “Wow, that’s loud”. You may not notice that some minutes later, but you definitely notice that when the loud sound starts. That’s what I mean, when I say you would have noticed a shaver which is loud enough to damage your ears in the morning.

    Human “sensors” are not especially good sensors for measuring absolute values (but they are quite good for change detection), but if a human leaves a “calibrated state” (like waking up), the ears are quite capable to differ between very loud and normal loudness.

    Regarding the 1/r^2 law: If that was always true, every noise would be infinitely loud if your ear were close enough to the source. Empirically it’s proven, that the sound of a raindrop falling on the ear is not a reason to reduce hearing capabilities in the future. So probably the shaver is completely safe.

    Nevertheless, I can feel the excitement of getting a decent measurement system – that’s what we as technically interested persons have fun with and learn from.

  • ZOG

    I have a low cost Jaycar DB meter (QM1591).

    I have two electric shavers.. my newer Panasonic ES8249 (foil)that I use all the time and my older Remington R835 (rotary).

    The Panasonic measures at 83 – 85dB. The Remington measures at 90-92dB.

    So yet another reason why the (newer pricier) Panasonic is substantially better for me.

    btw I took this sound meter to a gig by one of my fave bands SWANS and measured 120dB with it.. YES IT WAS LOUD.. and I had hearing protection in.. I want to keep enjoying music as I get older..

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