Red Line noise levels
Jan. 17th, 2010 07:49 pm![[identity profile]](https://www.dreamwidth.org/img/silk/identity/openid.png){kind=small}
philipph.livejournal.com posting in ![[community profile]](https://www.dreamwidth.org/img/silk/identity/community.png){kind=small}
davis_squareTo follow up on a previous thread that discussed noise levels on the Red Line on this side of the river, I've had to take the T a few times since then (mostly I bike), and I brought along my sound meter. Some rambling and some numbers after the cut...
The ambient noise level at Davis on the platform is about 60dB, with announcements going up to 80dB, at least if you're standing in the right spot.
Trains arriving and departing take the noise up to 95dB, and they idle at about 80dB.
There's a great variety in noise levels at various points between the stations. I've really only written down the peaks, some of which only last for a few seconds.
I'd need more patience and/or different equipment to really track how loud things are for extended periods of time.
In general, the 018xx series of cars are definitely quieter (inside) than the 017xx, 016xx and 015xx ones. By about 5dB.
There's a huge variation in noise levels based on how fast the train is moving. This difference seems to overwhelm pretty much anything else (number of passengers dampening the sound, and even old/new car models).
I really don't have enough raw data (well, 6 trips inbound, 4 outbound) to say much, given the variety of trainsets.
In general, however, peaks between the stations I travel on are all around 89dB to 91dB or so. I go between Davis and Kendall generally (and lately into Boston, too, but after Kendall, the noise level drops dramatically, both due to reduced speed and increased outside-ness, no doubt). I have no idea what things are like between Davis and Alewife.
I did go on one rather overwhelmingly louder trainset, I think it might have been 01700, that consistently peaked around 95dB between every station.
Both inbound and outbound, the stretch between Porter and Harvard seems to be the loudest (probably because of the max speeds and/or the squealing right by Harvard), but not by all that much.
Then again, it's hard to have any kind of conversation in the high 80s.
For the record, this is all measured on a Radio Shack Analog Sound Meter (currently available there for about $45... not sure what I paid for it when I bought it a number of years ago, probably something similar), set to "Slow" response and "A" weighting settings, in case you know/care what that means.
Hope this wasn't too much of a ramble.
If anyone wants to take more careful notes, I'd be willing to lend them my sound meter. I don't take the T often enough, but maybe someone else is obsessive enough to get all detailed about it and post their results more coherently.
The ambient noise level at Davis on the platform is about 60dB, with announcements going up to 80dB, at least if you're standing in the right spot.
Trains arriving and departing take the noise up to 95dB, and they idle at about 80dB.
There's a great variety in noise levels at various points between the stations. I've really only written down the peaks, some of which only last for a few seconds.
I'd need more patience and/or different equipment to really track how loud things are for extended periods of time.
In general, the 018xx series of cars are definitely quieter (inside) than the 017xx, 016xx and 015xx ones. By about 5dB.
There's a huge variation in noise levels based on how fast the train is moving. This difference seems to overwhelm pretty much anything else (number of passengers dampening the sound, and even old/new car models).
I really don't have enough raw data (well, 6 trips inbound, 4 outbound) to say much, given the variety of trainsets.
In general, however, peaks between the stations I travel on are all around 89dB to 91dB or so. I go between Davis and Kendall generally (and lately into Boston, too, but after Kendall, the noise level drops dramatically, both due to reduced speed and increased outside-ness, no doubt). I have no idea what things are like between Davis and Alewife.
I did go on one rather overwhelmingly louder trainset, I think it might have been 01700, that consistently peaked around 95dB between every station.
Both inbound and outbound, the stretch between Porter and Harvard seems to be the loudest (probably because of the max speeds and/or the squealing right by Harvard), but not by all that much.
Then again, it's hard to have any kind of conversation in the high 80s.
For the record, this is all measured on a Radio Shack Analog Sound Meter (currently available there for about $45... not sure what I paid for it when I bought it a number of years ago, probably something similar), set to "Slow" response and "A" weighting settings, in case you know/care what that means.
Hope this wasn't too much of a ramble.
If anyone wants to take more careful notes, I'd be willing to lend them my sound meter. I don't take the T often enough, but maybe someone else is obsessive enough to get all detailed about it and post their results more coherently.
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no subject
Date: 2010-01-18 12:59 am (UTC)So the difference of -5dB on the 018xx train cars means that they sound about 25% quieter than the other train cars, but in terms of things like damage to your ears (raw audio power) you're taking about 50% of the loudness.
At least, I think :)
Please read here if you really want to know more, don't take my word for it:
http://www.sengpielaudio.com/calculator-levelchange.htm
And here is a reference for loudness levels:
http://www.hyperacusis.net/hyperacusis/decibel+guide/default.asp
no subject
Date: 2010-01-18 01:07 am (UTC)85 decibels seems to be the consensus threshold for hearing loss. I usually wear earplugs on the T. Now I feel a little more justified in doing so.
no subject
Date: 2010-01-18 01:46 am (UTC)no subject
Date: 2010-01-18 01:49 am (UTC)no subject
Date: 2010-01-20 02:09 pm (UTC)no subject
Date: 2010-01-20 02:11 pm (UTC)Philipph you're the man!
Date: 2010-01-18 01:51 am (UTC)Here is some information regarding noise and hearing damage...
http://www.dangerousdecibels.org/hearingloss.cfm
no subject
Date: 2010-01-18 02:42 am (UTC)Sound is not something most people are particularly sensitive to (RE: all the ignorant snark over the jet noise in DS ;-)
Especially if they are already deaf...
Date: 2010-01-18 02:47 am (UTC)Re: Especially if they are already deaf...
Date: 2010-01-18 05:29 am (UTC)Re: Especially if they are already deaf...
Date: 2010-01-18 02:53 pm (UTC)no subject
Date: 2010-01-18 04:56 am (UTC)The audio geek in me is so happy you did this.
no subject
Date: 2010-01-18 04:58 pm (UTC)Ooops. fixed weighting in original
Date: 2010-01-18 05:13 pm (UTC)I've adjusted it in the original post now.
Re: Ooops. fixed weighting in original
Date: 2010-01-18 05:21 pm (UTC)Re: Ooops. fixed weighting in original
Date: 2010-01-18 06:40 pm (UTC)a) I was having to keep an eye on it and take notes as I watched it and
b) I sincerely doubt that there are spikes that come close to actually doing damage for the short periods of time they occur
I didn't bother.
Next time I take the T I might just give the fast option a try once to see how high it goes (since I have to pick the 10dB rage ahead of time, it'll be a bit tricky)
Re: Ooops. fixed weighting in original
Date: 2010-01-19 07:15 pm (UTC)Based on today's trip inbound, there don't appear to be any real sudden spikes in noise that make the "fast" setting show anything particularly different from the "slow" setting.
Then again, this was a surprisingly quiet 016xx trainset. Very loud on the outside, fairly quiet ride inside.
no subject
Date: 2010-01-19 03:25 am (UTC)Now I wonder if taking audio recordings of T rides using my iPhone could be analyzed for a plot and cumulative/average reporting of noise levels. Calibration might be hard.
no subject
Date: 2010-01-19 04:30 pm (UTC)