Cheap Sound Meter?

nomoon · Post by **nomoon** » Wed Apr 20, 2005 7:21 am

Does anyone know if a cheap sound meter is available? A friend of mine used to have a Radio Shack sound meter which cost around $35, though they don't seem to sell this item anymore. I don't remember how sensitive it was, but it did have two settings.... I think "A" and "B". I would just like to be able to make objective quantitative measurements of various things around the house in addition to my computer mods.

Does anyone know how to quiet a dachshund?

Jason
(extreme dachshund photos on my website below)

sthayashi · Post by **sthayashi** » Wed Apr 20, 2005 8:03 am

It looks like they stopped carrying their old SLM, but they got a new one for almost the same price.

33-4050
It only goes down to 50dB, which is WAY too loud for SPCR use. This SLM is better used for tuning a home theater system such that each speaker is producing the same volume of audio.

The two settings were the weightings. A-weighting and C-weighting. C is supposed to be flatter, but A is closer to what we actually hear.

I have no idea how to humanely quiet a dachshund.

yeha · Post by **yeha** » Wed Apr 20, 2005 8:33 am

hm if i was looking to measure sound levels, i'd get a microphone with very low self-noise. there are $200 models that are rated 12-13 dba self-noise, and if that's true (i'd test one before buying) you could do decibel measurements on most anything above 16-17 db. i believe many sound editing programs support dba weighting analysis.

these microphones are the kind used to record animal noises in the dead of night - they're expected to pick up digging, sqeaking and eating noises from several dozen yards away, and if you've ever heard the clarity of nature documentaries i think they'd be perfect for quiet pc analysis. i looked up a bunch of these micrphones a while back - the best (obviously) are around $1000 for self-noise figures around 5 db and at that price you may as well buy the spl meter that mikec uses, however there were several $150-$200 models that seemed pretty good, like the rode nt3.

Green Shoes · Post by **Green Shoes** » Wed Apr 20, 2005 9:14 am

yeha wrote:hm if i was looking to measure sound levels, i'd get a microphone with very low self-noise. there are $200 models that are rated 12-13 dba self-noise, and if that's true (i'd test one before buying) you could do decibel measurements on most anything above 16-17 db. i believe many sound editing programs support dba weighting analysis.

these microphones are the kind used to record animal noises in the dead of night - they're expected to pick up digging, sqeaking and eating noises from several dozen yards away, and if you've ever heard the clarity of nature documentaries i think they'd be perfect for quiet pc analysis. i looked up a bunch of these micrphones a while back - the best (obviously) are around $1000 for self-noise figures around 5 db and at that price you may as well buy the spl meter that mikec uses, however there were several $150-$200 models that seemed pretty good, like the rode nt3.

Don't forget that those dB ratings are just for the microphone. To actually measure the decibel level on, say, your computer, you have to go through both a preamp and an A/D converter. Under normal circumstances this can easily add 15dB to your noise floor, so you're looking at dropping another $1,000 or so just to be able to accurately measure with your $200 mic. I like Rodes, they're good mics (especially their tube mics), but probably not so hot for that purpose.

Also don't forget that nature documentaries are using either shotgun or parabolic mics.....both of those basically have hyper-hyper-hyper cardioid patterns, and are designed specifically to be able to localize sound (think of the guys on the side of a football field holding those weird mini-satellite contraptions...it's how they can record a crushing hit or a snap count with clarity). A basic cardioid pattern like most any mic you can get for under $200 is going to pick up much more ambience, which of course raises the noise floor higher than we can really measure.

So, long answer to short question...

I don't know of a cheap way to be able to monitor such low levels of noise. The equipment has to be so sensitive (read: expensive) in order to do so.

Green Shoes · Post by **Green Shoes** » Wed Apr 20, 2005 9:17 am

Oh, and I don't have any personal experience with extreme dachshunds, but I know that your everyday garden-variety dachshunds can be effectively quieted by suspending them in clothing elastic

yeha · Post by **yeha** » Wed Apr 20, 2005 9:56 am

Green Shoes wrote:Don't forget that those dB ratings are just for the microphone. To actually measure the decibel level on, say, your computer, you have to go through both a preamp and an A/D converter. Under normal circumstances this can easily add 15dB to your noise floor, so you're looking at dropping another $1,000 or so just to be able to accurately measure with your $200 mic. I like Rodes, they're good mics (especially their tube mics), but probably not so hot for that purpose.

is the preamp necessary, and are a/d conversions really that bad nowadays? i was looking at an m-audio external recording box, snr upwards of 100 dba. basically, if i could try out one of those microphones i'd record some known noise levels with it - panaflos, nexus, etc. - see if they can actually pick up anything but self-noise from 1 metre away, then use those recordings (if they're good) as a base for dba comparisons.

frankgehry · Post by **frankgehry** » Wed Apr 20, 2005 10:51 am

Hi,

I bought a $50 audio technica ATR55 thinking it was a really good mike and connected it directly into my motherboard sound card and had fair results. MikeC measures fan noise 3 inches away so its hard not to be directional that close. The ATR55 is a video mike with a shotgun and normal position. I picked up a m-audio preamp DMP3 which is a pretty good mid line model. This helped quite a bit as far as getting a good signal, but I really need a better mike. A Rodes shotgun for $150, which is also made for video recording, is pretty good. I didn't really know good mikes where that expensive. I'm sure my on board audio card is not very good, but if I had the Rodes mike, the DMP3, and an m-audio sound card I'm sure I could make excellent recordings. I've lost interest for the moment, but a salesperson at bhphoto.com in NY helped me quite a bit with microphones after I told him what I was trying to do. www.bhphoto.com has a real good selection of microphones and other equipment to browse through. - FG

Devonavar · Post by **Devonavar** » Wed Apr 20, 2005 11:52 am

frankgehry wrote:MikeC measures fan noise 3 inches away so its hard not to be directional that close.

No, MikeC records fan noise at 3". We measure it at 1m.

frankgehry · Post by **frankgehry** » Wed Apr 20, 2005 12:04 pm

This is what I read, so now its 1 meter. Fine. Which ones are measured at 1m and which ones are measured at 3" and what distance will be next.

http://www.silentpcreview.com/article190-page4.html

Post by **Rusty075** » Wed Apr 20, 2005 12:19 pm

FG, you missed the subtlety of Devon's comment:

The 3" distance is used to make recordings of noise, for listening comparisons. Measurements, as in dBa level, have to be made at 1m to be useful.

"Recording" and "measuring" are not interchangable. A close recording distance is used to maximize differentiation of the source from the ambient, but the nearfield distortions induced are too large in proportion to the source sound spl to make dBa measurements taken at that distance useful, which is why the standard distance of 1m is used for measurements

frankgehry · Post by **frankgehry** » Wed Apr 20, 2005 12:51 pm

R,

Oh I see. Recordings at 3", and sound meter readings at 1m. And I thought I was going to have to redo all of my 100 noise recordings again. - FG

Green Shoes · Post by **Green Shoes** » Wed Apr 20, 2005 5:37 pm

yeha wrote:is the preamp necessary, and are a/d conversions really that bad nowadays? i was looking at an m-audio external recording box, snr upwards of 100 dba. basically, if i could try out one of those microphones i'd record some known noise levels with it - panaflos, nexus, etc. - see if they can actually pick up anything but self-noise from 1 metre away, then use those recordings (if they're good) as a base for dba comparisons.

Because of the quality of A/D converters a preamp is necessary, just to get the signal above the noise floor. And yes, I use an M-Audio external box myself, but they aren't what I would call cheap. And it's very good, but still much more distortion than you would get from a good analog or digital recording path (well, one without the PC).

Cheap Sound Meter?

Cheap Sound Meter?

sound recording

Re: sound recording