[fran]

Hi all,


I went to a our yearly Young Scientists Competition last weekend - and I was pretty impressed with the level of stuff on show. OK, some of it was fairly pedestrian, but there were many really good exhibits - and all from kids in the 12-16 age group.

Anyway there were a good number to do with hearing and headphones - which is interesting given the huge number of MP3 players in use. Anyway here is a pic of just one of the exhibits -

The Damaging Effects of the Different Types of Headphones



The students made a dummy ear, and conducted a series of experiments with various music types and measured SPLs in the ear with a meter. They measured in ear, on ear, clip ons and circumaural phones with classical, pop, metal and dance music.

Maybe unsurprisingly the headphones that produced the higest SPLs were the ones that were closest to the eardrum (ie IEMS) and Dance was the music type with the highest SPLs. Classical the least.

I thought it was very good work!

Another one I saw investigated the treatment of tinnitus with low frequency soundwaves - interesting too I thought.


With brains like those coming on maybe there is hope for the world!


Comments please!

Fran


Ps:
FWIW, the winners developed and tested a quick and easy method for determining somatic cell counts (SCC) in milk - which is one of the criteria that determines milk quality and price paid by the processing companies. They found that the viscosity of milk when mixed with a certain amount of detergent was an indicator (quantitative) of SCC in milk. It was easily worth a poster at a conference, never mind a science exhibition.

 

[scompton]

Kind of a bogus test. If a particular type of music is mixed louder, I just turn down the volume. And I use IEMs because I can listen at lower SPL. It's true that if I plug my AKG K240 Sextett into my iPod, set the volume, and then leave it there and listen to my IEMs, the SPL will be in hearing damaging range. But most people are not dumb enough to do that.

On my daily subway commute, the people doing the most damage to their hearing are the people not using IEMs. I can listen at 70dB with my IEMs. I measured the average background noise on the train and it was 95-105dB. People listening with full sized, non-isolating headphones are probably listening at at least 110dB.

 

[00264167]

i remember doing this stuff in school too which was a good thing.

isolating ear canals and iem's are better than the ear bubs that were around then that you had to blast your ears just to hear them over the background.
i also remember them saying speakers werent too good for you either but i cant see why as long as theyre at talking volume, i cant imagine any bad effects at that level.

the trouble with headphones is i read that its not good to listen at X amount of db but how are you supposed to know how many db your volume is at.

this is the WHO scale

70 dB 24 hrs.
73 dB 12 hrs.
76 dB 6 hrs.
79 dB 3 hrs.
82 dB 1.5 hrs.
85 dB 45 mins.
88 dB 22 mins.
91 dB 11 mins.
94 dB 6 mins.
97 dB 3 mins.
100 dB 1.5 mins.
103 dB 45 secs.
105 dB 22 secs.
107 dB 11 secs.
110 dB 6 secs.
113 dB 3 secs.
116 dB 1.5 secs.
119 dB <1 sec.

 

[Lornecherry]

I wonder, do we have an Audiologist among us? ... as they could certainly lend some credible insight to this discussion.

 

[eruditass]

of course those that sit closer will be able to produce a higher SPL as SPL falls of with distance squared. And even more so due to the fact that they are smaller and often much more efficient.

However, isolating ones that sit close to the eardrum allow something that they and many others fail to take into account or measure, the isolation and reduction in noise floor, resulting in a lower SPL for the same perceived SPL/music quality.

I suppose the general message is good, don't listen at high volumes, you will damage your ears, but it is mixed in telling you to use headphones that sit further away. Kids will probably continue to listen to music in public, and switch to circumaural headphones that don't isolate, and will damage their hearing even if they lower the perceived volume (essentially music to noise ratio).

 

[fran]

All good points guys. I spoke to the girls who did the work and they indicated that they intended to follow up with more research. to be honest I was impressed that they even went to the bother of making a false ear on which to take their measurements.

Please keep the comments and suggestions coming - I will be emailing them a link to this thread so it will be great for them to read this kind of stuff from high end and discriminating users.

Fran

 

[scompton]

Quote:

Originally Posted by Lornecherry /img/forum/go_quote.gif I wonder, do we have an Audiologist among us? ... as they could certainly lend some credible insight to this discussion.

This topic, or the similar topic about IEMs are bad for you, comes up every couple of months. There are a few threads where audiologists have chimed in saying basically what I said. If you listen at the same level of course IEMs are bad for you. The advantage of IEMs is that you can listen at a lower level because they isolate you from the background noise.

It's fairly easy to measure the SPL of full sized headphones. IEMs and circumaural headphones are harder. Here's a post with links on measuring SPL

Quote:

Originally Posted by scompton /img/forum/go_quote.gif Here's a couple of posts on how you can measure with an SPL meter. I'm sure they're not perfect, but you can get at least a ball park figure. Here's how I measure IEM SPL. http://www.head-fi.org/forums/2850576-post102.html From the same thread, here's how to measure SPL for a full sized can http://www.head-fi.org/forums/2767153-post42.html From what I've read, the best measure for IEMs is done by an audiologist with a small microphone in your ear with the IEMs in place. I've not yet found an audiologist in my area that does this though.

 

[00264167]

Quote:

Originally Posted by scompton /img/forum/go_quote.gif This topic, or the similar topic about IEMs are bad for you, comes up every couple of months. There are a few threads where audiologists have chimed in saying basically what I said. If you listen at the same level of course IEMs are bad for you. The advantage of IEMs is that you can listen at a lower level because they isolate you from the background noise. It's fairly easy to measure the SPL of full sized headphones. IEMs and circumaural headphones are harder. Here's a post with links on measuring SPL

interesting...were your train and iem measurements 'A' weighted

 

[csroc]

Agree on the comments about somewhat bogus results. IEMs will definitely protect your ears better. I can't imagine using anything else on an airplane for example. When I see people using their stock iPod earbuds on a plane I wonder how many dB they're really subjecting their ears to.

 

[nsx_23]

People on buses with ibuds so loud that I can hear them from 4 rows down. I'm surprised their ears aren't bleeding afterward.

Then again, there are IEM users out there who just pump the volume out really loud, thus damaging their hearing even faster.

 

[Hanafuda]

It's a kid's science fair project. Of course his data is flawed. Still a darn good science fair project, though. Mine sucked, consistently from year to year (It's a cup of dirt).

 

[my.self]

to nsx 23, i know what u mean, at school, i remember hearing a few ppl while at my locker playing there ipods at im pretty sure full blast through their ibuds. i wasnt facing them at first so im like, hey whos using those speakers? i turn around and then i go "woah..." i wonder if its even enjoyable for anyone to play there music at 100% maxed out through ibuds. ill maybe last under 5 seconds then pull em out.

 

[nsx_23]

I'll last 1 second. Max.

I have extremely sensitive ears (even dishes clashing together hurts my ears), so I religiously stick to using IEMs on the street. Heck, I carry around ER-20 plugs on me all the time.

 

[TimmyMac]

Ya, kids can't really form anything like scientific experiments. Cool though.

 

[scompton]

Quote:

Originally Posted by 00264167 /img/forum/go_quote.gif interesting...were your train and iem measurements 'A' weighted

It's been a while so I don't really remember.

Quote:

Originally Posted by nsx_23 /img/forum/go_quote.gif People on buses with ibuds so loud that I can hear them from 4 rows down. I'm surprised their ears aren't bleeding afterward. Then again, there are IEM users out there who just pump the volume out really loud, thus damaging their hearing even faster.

One day on the subway, I heard someone's music when I had my IEMs on. It was between songs from my iPod so no sound though my IEMs, but they were 10 feet away.