[ilmari]

Hello

A new member here, and barging straight on making a new thread. Please be gentle on me

A little background. I work in a high noise environment, 85 - 100+ dB. There's alot of lower frequencies present, not so much in the higher frequencies. I've been stepping up the ladder, from using hearing protection cups with built in radio, pathetic sound quality and noisy radio reception, regular earbuds pressed against solid yellow foam plugs inserted into ear, volume turned up to max to get through the foam, Koss Plug and most recently Sennheiser CX300. All worn under regular hearing protection cups.

As for physical comfort, I find that I can wear foam plugs and Koss Plug in ear all day long without problems. The CX300's rubber irritates my ears slightly.

The real problem I have with CX300, is that they make me really really uncomfortable. There's something constantly present in my head, a rumbling sound that really sort of both tranquilizes and makes me at unrest and stressed out at the same time. After a week of using the CX300 at work I just had to stop. My ears were beginning to hurt, even when I didn't play anything through them, and music sounded just strange.

I thought I was just imagining things, or that the presence of the CX300 and the cable coming out from underneath the cups was creating resonance, or..... well I went back to Plug, though it also annoys me to no end. I wore out my last pair and haven't been able to find a decent new one. There's so much individual variation between them. Replacement pair 1 had right earbud at half the volume of the left. Replacement pair 2 has significantly different frequency response between right and left... sigh.

As I was looking for a replacement, I was looking at headroom's measurements of various IEMs, and noticed something startling on the isolation graph:

http://http://www.headphone.com/technical/product-measurements/build-a-graph.php?graphID%5B0%5D=603&graphID%5B1%5D=675&gr aphID%5B2%5D=609&graphID%5B3%5D=&graphType=2&butto nSelection=Compare+Headphones

What's going on at <30Hz? Is that amplification of the lower frequencies? Maybe I wasn't imagining things afterall...

Now I am slightly curious. What causes this? Has anyone else also experienced this in real life? Is it all bogus and just a side-effect of measurement methodology?

I am considering Shure E4C next, isolation looks excellent, and considering I can wear the Plug's foam tips forever I think I'll love Shure's foam tips

Maybe "excellent" is the wrong word, the isolation looks unbelievably good...

 

[manaox2]

You can probably get the shure se500 or se530 (same IEM) for a good price on the used boards ~260 and these are a great step above the e4c according to most. They actually do bass and do it well.

 

[kwkarth]

Quote:

Originally Posted by ilmari /img/forum/go_quote.gif [size=xx-small]Hello A new member here, and barging straight on making a new thread. Please be gentle on me A little background. I work in a high noise environment, 85 - 100+ dB. There's alot of lower frequencies present, not so much in the higher frequencies. I've been stepping up the ladder, from using hearing protection cups with built in radio, pathetic sound quality and noisy radio reception, regular earbuds pressed against solid yellow foam plugs inserted into ear, volume turned up to max to get through the foam, Koss Plug and most recently Sennheiser CX300. All worn under regular hearing protection cups. As for physical comfort, I find that I can wear foam plugs and Koss Plug in ear all day long without problems. The CX300's rubber irritates my ears slightly. The real problem I have with CX300, is that they make me really really uncomfortable. There's something constantly present in my head, a rumbling sound that really sort of both tranquilizes and makes me at unrest and stressed out at the same time. After a week of using the CX300 at work I just had to stop. My ears were beginning to hurt, even when I didn't play anything through them, and music sounded just strange. I thought I was just imagining things, or that the presence of the CX300 and the cable coming out from underneath the cups was creating resonance, or..... well I went back to Plug, though it also annoys me to no end. I wore out my last pair and haven't been able to find a decent new one. There's so much individual variation between them. Replacement pair 1 had right earbud at half the volume of the left. Replacement pair 2 has significantly different frequency response between right and left... sigh. As I was looking for a replacement, I was looking at headroom's measurements of various IEMs, and noticed something startling on the isolation graph: http://http://www.headphone.com/technical/product-measurements/build-a-graph.php?graphID%5B0%5D=603&graphID%5B1%5D=675&gr aphID%5B2%5D=609&graphID%5B3%5D=&graphType=2&butto nSelection=Compare+Headphones What's going on at <30Hz? Is that amplification of the lower frequencies? Maybe I wasn't imagining things afterall... Now I am slightly curious. What causes this? Has anyone else also experienced this in real life? Is it all bogus and just a side-effect of measurement methodology? I am considering Shure E4C next, isolation looks excellent, and considering I can wear the Plug's foam tips forever I think I'll love Shure's foam tips Maybe "excellent" is the wrong word, the isolation looks unbelievably good...[/size]

[size=large]The UE and the Sure are passive attenuators. Low frequencies can only be "effectively" attenuated by active cancellation due to bone/body conduction of low frequencies.[/size]

 

[Megalomania]

There's not much you can do to get rid of low frequency sound. Think about when you're at a light and the white kid who thinks he's ghetto because he has 'fubu' clothing on pulls up next to you in his "totally wicked" Honda - you can't hear the music (thank god), but you can feel the vibrations from the subwoofer, because loud bass passes for talent these days. The good news is, there aren't many normal sources of low frequency sound like that, and those that are around will eventually go away as the people listening to it lose their hearing

.

 

[kwkarth]

read post 3

 

[Caribou679]

Dear Ilmari, welcome aboard.

You can find Koss the Plug full on ebay. No worries!

If you put music underneath your regular ear protection, doesn't this put you a bit" out of hearing " what is happening in your work environnment? Isn't this a bit risky?

 

[ilmari]

It does reduce awareness slightly, but it's not a place where sound is vital. The few sound alerts that do exist are paired with powerful strobe lights as well. Usually I keep the music at the lowest setting on my mp3 player, unless it's a very quiet or a very good song. To completely drown out external noise I'd need to use ear damaging volume.

Re SE530, I've only read good things about them and would be tempted to get them, with the PTH unit which I can't seem to find separately anywhere local, but headroom's isolation measurements show a worrying curve towards 20Hz that goes towards 0dB..

I understand that low frequencies are next to impossible to block out. You hear them with through and with your entire body and not just your ears, when things do go wrong at work the first cues are usually a thumping transmitted through the floor, tickling your feet. (think of Jurassic Park where the T-Rex causes rings in a glass of water

Even if isolation is near impossible, I'd atleast hope that there'd be no amplification. Looking at the graph it looks like CX300 amplifies external 20Hz sounds by 10dB! It seems kinda incredible, but I did experience alot of discomfort and increased sound pressure by just wearing them. At the same time, headroom's measurements show -20dB for 20Hz on Shure E4C and UE super.fi 3 Studio (and both companies' tripple driver products measured close to or over 0dB at 20Hz).

Is this apparent amplification caused by the relatively large surface area of plastic exposed on the outside of the ear, connected to some smaller surface exposed or routed to the inside of your ear? If so then why isn't it happening for all of them? Shape? Size? Glossy hard plastic vs rough matte surface?

 

[kwkarth]

Quote:

Originally Posted by ilmari /img/forum/go_quote.gif ... Is this apparent amplification caused by the relatively large surface area of plastic exposed on the outside of the ear, connected to some smaller surface exposed or routed to the inside of your ear? If so then why isn't it happening for all of them? Shape? Size? Glossy hard plastic vs rough matte surface?

Listen, it's a fools errand to try and attenuate low frequency energy passively.
Period, end of story. Stop torturing yourself.

You may laugh at me for saying this, but one of the most effective solutions for you would be to get a pair of BOSE QC-2's and use them for noise reduction only (they work quite well for this purpose) and use some ear buds/IEM's underneath for tunes. An un-tested possible solution is the Sennheiser PXC-450.

I've listened to the BOSE QC-2 and while the sound quality sux, the noise isolation is pretty good. You can wear them without the cord attached and just use them as hearing protectors. They will set you back about 300 bills, but the Sennheiser solution, which may or may not work, will set you back about $450.

 

[Caribou679]

Quote:

Originally Posted by kwkarth /img/forum/go_quote.gif Listen, it's a fools errand to try and attenuate low frequency energy passively. Period, end of story. Stop torturing yourself. You may laugh at me for saying this, but one of the most effective solutions for you would be to get a pair of BOSE QC-2's and use them for noise reduction only (they work quite well for this purpose) and use some ear buds/IEM's underneath for tunes. An un-tested possible solution is the Sennheiser PXC-450. I've listened to the BOSE QC-2 and while the sound quality sux, the noise isolation is pretty good. You can wear them without the cord attached and just use them as hearing protectors. They will set you back about 300 bills, but the Sennheiser solution, which may or may not work, will set you back about $450.

Follow this advice, if you need to listen to music at your work, get an active sound isolation with IEM underneath. For the iaudiophile in you, enjoy it outside for the work environnement!!

 

[ilmari]

Well, "real" hearing protection foam plugs can attenuate 29.1dB @ 63Hz and 32.4dB at 125Hz passively, for example (E-A-R Superfit 36). QC2 seems to be in the same league as passive cups @ 125Hz.

But I think I'm going to trust headroom's measurements as guide, their synthetic head must be very similar to my own head when considering CX300

 

[slwiser]

I use ATH-ANC7s.

 

[edstrelow]

If low frequencies may enter your hearing through bone and body conduction as was suggested above, I don't think an active headphone noise cancelling system will do anything for that source of noise although I agree that it will reduce airborne noise.

I worked with soundproof labs for several years and to get rid of this kind of noise by passive means you need mass, i.e. foot thick concrete walls, and rooms within rooms with the inner room mounted on springs.

 

[scompton]

I use my UM1 under Peltor 30dB ear muffs when I want to block loud noise like power tools. It works very well. It might not work as well as the Bose, but it's a lot cheaper and probably good enough. I happen to own the UM1, but any IEM will work. You probably something with foam tips. The rubber tips used in the CX300 and Super.fi don't isolate all that well.

If you look at the chart, these IEMs reduce low frequencies by 10-20dB. Looking up the Peltor ear muffs, the top ones reduce 21dB at 120Hz (that the lowest their chart goes). You'll get about 50dB reduction at 120Hz. That's pretty good. The Bose might do better, but this looks good to me.

 

[kwkarth]

Quote:

Originally Posted by edstrelow /img/forum/go_quote.gif If low frequencies may enter your hearing through bone and body conduction as was suggested above, I don't think an active headphone noise cancelling system will do anything for that source of noise although I agree that it will reduce airborne noise. I worked with soundproof labs for several years and to get rid of this kind of noise by passive means you need mass, i.e. foot thick concrete walls, and rooms within rooms with the inner room mounted on springs.

Well, you are certainly entitled to your opinion.

I can tell you from personal experience that active noise cancellation is the only EFFECTIVE and practical means of reducing infrasonic and low frequency noise at someone's eardrum.

Do you expect someone to don a lead suit for the working environment?

Active noise cancellation is successfully used EVERY DAY all over the world, in thousands of applications for military, industrial, civilian, and aviation needs.

 

[kwkarth]

Quote:

Originally Posted by ilmari /img/forum/go_quote.gif Well, "real" hearing protection foam plugs can attenuate 29.1dB @ 63Hz and 32.4dB at 125Hz passively, for example (E-A-R Superfit 36). QC2 seems to be in the same league as passive cups @ 125Hz. But I think I'm going to trust headroom's measurements as guide, their synthetic head must be very similar to my own head when considering CX300

Again, from personal experience, I can tell you with 100% assurance that passive attenuation is not effective for low frequencies. A foamie may stop 63 Hz from passing through, but that same 63Hz, and more importantly, lower frequencies than that, will modulate your whole body, and you will hear/feel it in your head as well as everywhere else. Properly designed active noise cancellation will reduce what is hitting your eardrums, even if it's coming through your body. It works, it works, it works. Passive attenuation does not.