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Susannah Thorpe
tiny microphones to record environmental sound
on Sep 11, 2015 at 7:48:02 am

Hi,

We are beginning a new research project in which we want to be able to quantify the level and type of noise people experience in the journeys they make through towns, parks and forests on their way to work, walking or cycling. We want to instrument the participants, preferably on their head (but wires can lead to a back pack with data logging equipment in), so its important to have small but hiqh quality instrumentation.

With this in mind, could any one advise which microphone would be most appropriate? We would like to pick up all sounds like bird song, traffic noise, trees rustling in the wind, so the microphone needs to be sensitive, but not so sensitive we just pick up loads of 'noise'. I need to download it to some sort of data storage device (any advice?) probably stored in the backpack, and I was anticipating then analysing it with Avisoft-SASLab Pro software, which produces a spectrograph of the noise and I think can quantify volume.

Thanks for any advice and help you can give!


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Peter Groom
Re: tiny microphones to record environmental sound
on Sep 11, 2015 at 11:40:01 am

Hi
Others with more indepth mic knowlege will speak up im sure, but I feel you may have a bit of a conflict of interests here.
You want something small and possibly headworn - which is perfectly do able BUT in general these small mics (usually called lapel or lav mics) are designed to only pick up very nearby sounds. That is why theyre used and positioned where they are for speech pickup. They dont pick up general ambience very well.
Mic s that are designed to pick up more of the ambiance, have greater "reach" BUT this is achieved by the mic designers by creating a long or "shotgun" style mic, which isnt as neat and convenient as youre hoping for. So Im not sure what to recommend but you may need to re think the aims.
Performance versus size and convenience!.

Ty is more expert in mics and im sure can expand further.
Peter

Post Production Dubbing Mixer


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Susannah Thorpe
Re: tiny microphones to record environmental sound
on Sep 11, 2015 at 12:57:25 pm

Thanks so much, Peter. Thats really useful. I guess in my naivety I have assumed that if the microphone is positioned next to the ear, then it will pick up what the ear hears, but maybe that's not the case! I did find this one Sonic Studio’s DSM-6S/L: http://www.sonicstudios.com/dsm.htm#chart, which seems designed for ambient noise, but I have never tried it. Does anyone have experience of it? Thanks very much, Susannah


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Richard Crowley
Re: tiny microphones to record environmental sound
on Sep 11, 2015 at 5:17:57 pm

Tiny electret condenser microphone capsules or even smaller MEMS (micro-electro-mechanical systems) mics are quite plentiful and inexpensive. And they are remarkably accurate for their size and cost.

It is true that we normally try to minimize ambient sound when we are recording speech/dialog. But placement of one of these tiny mic capsules on a headband with the mic positioned at the back of the head would "optimize" the ambient sound pickup.

Some issues to address would include:

1) Minimizing wind noise with a foam gag or even a furry cover. That is what we use when recording outdoors to virtually eliminate wind nose. That is the wind noise that directly impinges on the diaphram of the mic. It would still properly pick up other wind noises like rustling leaves, etc. If the mic were positioned at the back of the head it would also reduce the wind noise from jogging cycling, etc. where the subject is moving through the outdoors.

2) Separating deliberate subject noises (specifically speech) from the ambient sound (or sound-level). Maybe you could convince your subjects to faithfully use a mute button when they are speaking, but that seems unlikely. Or maybe you could statistically throw out the outlying data points as uncorrelated anomalies.

3) Recording the data. Do you want to actually record the sounds, or do you just want to record the SPL (sound pressure level)? Depending on your resources, you could devise a relatively inexpensive gadget perhaps the size of an Altoids tin that would record average SPL every 10 seconds with a time-stamp. That could be done with a tiny Arduino microcontroller which is $5 and the size of a postage-stamp. Plus another $10-15 worth of circuit for the timestamp and audio level conversion. There are plans for time-of-day circuits (using RealTimeClock RTC chips) and for sound level measurement (both hardware and software) out there on the internet.

Here are just a few items of interest. There are hundreds more.
https://www.sparkfun.com/products/8635
https://www.sparkfun.com/products/10028
http://www.adafruit.com/products/1713
https://learn.adafruit.com/adafruit-microphone-amplifier-breakout/measuring...


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Susannah Thorpe
Re: tiny microphones to record environmental sound
on Sep 15, 2015 at 12:47:09 pm

Dear Richard and Ty

Thanks very much for your messages! I do want to record the actual noises not just sound level, because we will then use Avisoft software to analyse the spectrograph of sounds to try and ID different sounds such as bird song, traffic, to understand the noise environment and correlate different types of noise (or spectrograph patterns) with the participants physiological state. One final question! would the Tiny electret condenser microphone capsules or micro-electro-mechanical systems allow me to do that because they are clearly substantially cheaper than the microphone systems? I guess the other relevant thing to point out is that I will also get video data with a head cam and light data, so will need to synchronise all systems together. Thanks everyone, this is incredibly helpful! Best Wishes, Susannah


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Ty Ford
Re: tiny microphones to record environmental sound
on Sep 15, 2015 at 2:18:15 pm

Hello Susannah,

The Zoom micro cameras I have used and reviewed - the Zoom Q4 and Q8 have very respectable audio sections. I could envision one of them being used as both the audio and video recorder.

http://tyfordaudiovideo.blogspot.com/2014/11/zoom-q4-1080p-with-lcd-viewer-...

http://tyfordaudiovideo.blogspot.com/2015/05/zoom-q8-like-q4-but-more.html

You might also do well to consult with Julian Treasure who speaks a great deal about sound and noise. I was with him yesterday on a shoot concerning an Armstrong noise reduction product. He's given a number of TED talks about sound.

Yes. there is quite a lot to know about how sound affects us; not only physically, but psychologically…and spiritually. I do believe that noise pollution can be toxic; more so to some than to others. Likewise, sound therapy can be expected to be more or less effective, depending on the individual.

I've been working with therapeutic sound for about eight years now.

http://www.tyford.com/Ty_Ford_Chakra_Soundscapes.html

Regards,

Ty Ford
Cow Audio Forum Leader

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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Ty Ford
Re: tiny microphones to record environmental sound
on Sep 11, 2015 at 5:25:19 pm

Hello Susannah and welcome to the Cow Audio Forum.

There are several companies that sell smal mics that clip on eye glasses to record ambient sound.

http://www.core-sound.com/mics.html

There are also mic systems from SonicStudios. http://www.sonicstudios.com/dsm.htm

Here's a review I did some time ago for their DSM mics.

Regards,

Ty Ford

DSM Mics

Pro: easy to use, hard to spot Con: slightly noisy

Ty Ford Baltimore, MD

Surreptitious recording, stealth mics, recording stuff when you don't want
somebody (or anybody) to know about it. That's not EXACTLY what Sonic
Studio's DSM mics allow you to do, but it's a fair description. I mean, if
you saw somebody walking around with two small wired pods, each the
size of a dime, attached to their glasses frames, it would raise some
questions. That's provided you noticed in the first place. I've worn the DSM
mics in public without them being noticed. The bigger the crowd, the less
likely anyone will notice.

DSM stands for Dimensional Stereo Microphone. The DSM-6 Signature
series ($400) I tried are hand-selected for full frequency response, -.25dB
and phase matched. The DSM-6 Standard set ($300) is matched within 1dB
at 1KHz. Sonic Studios in Reedsport Oregon makes these high-quality,
electret condenser mics and other cabling paraphernalia to hook them up
to DAT machines and other audio devices. Granted these are electret mics,
so there is some noise relative to RF condensers, but in cases where
portability is important and the sound levels are high enough, the smaller
electrets are hard to beat. And, there's no phantom power supply to worry
about.

Each mic is an omnidirectional pressure type, using a proprietary back-
electret omni-directional condenser element. Frequency response starts
at 5Hz and goes as high as 23KHz. The capsule is totally sealed except for
a pressure relief hole for altitude equalization. Omni they may be, but like
the human ear, they are directional at higher frequencies. Each mic is
encased in water-proof vinyl and comes with a small loop that slides over
the side pieces of a pair of glasses. There's a windscreen/headband (DSM-
WHB, $100) or you can try the 16lb. dummy head (DSM-GUY, $1,000 with
head, tripod, WHB and two cases) which means you don't have to stand in
one place not moving your head during recording. The good thing about
using your own head and headphones is that you can move to precisely the
right spot to get a very nice stereo recording.

DSM's will also power the hard-to-find Sony 24-bit SBM-1 (Super Bit Map)
outboard A/D converter that uses the proprietary 7-pin I/O on the Sony D3,
D7 and D8. Super Bit mapping is always ON on the SBM-1 and requires a
heavier outboard battery, which of course, Sonic Studio also has. They
even have a $75 mic plug-in upgrade that allows direct power and input
deck connection for the D8, so you don't need the PA-6 power adapter for
powering the electret. The DSM-6 and 6S both come with a 1/8" molded
stereo plug. I needed XLR's. Sonic Studios had them plus six others kinds of
connectors, a number of headphone/line drivers and external power pack
that can greatly lengthen continuous recording time.

IN THE FIELD I've walked up on live performances wearing the mics and a
portable DAT machine, and walked away with a very good representation
of the performance. You get better results when the performance is done
without a PA. With a PA you get a nice recording of the performance
through a PA. You also get better recordings when the audience doesn't
make noise, which never happens. So, logically, that means the DSM's are
really good at recording people ambiences.

They're also useful in the studio. I got some very nice stereo acoustic
guitar recordings by attaching the mics to my glasses and leaning over the
face of my D28S Martin while I played. The binaural effect made for an
extremely and natural sound. If you've got some extra tracks, recording a
few instruments this way could add a lot of dimension to the mix, even if
you pan the pairs around a bit to make room for other instruments. Instead
of using delay on a single track to spread the sound of the instrument, this
method may result in something more real or dimensional. Combining the
two tracks to mono caused a very minor amount of high frequency loss due
to the expected phase cancellation. Also, if the sound source is low in
level, you have to get very close to keep the electret noise minimized.

For standard playback you'll have to tweek your monitors to reproduce the
stereo image correctly. Angling them in to cross at a point a few feet in
front of me resulted in success, otherwise I had trouble placing elements
of the sound in the right place on the stereo spectrum. The same sort of
thing happens with X/Y mic techniques. Headphones work best. If you're
planning on a "headphones only" show, the DSMs are indispensable.

Ty Ford may be reached at http://www.tyford.com

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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Richard Crowley
Re: tiny microphones to record environmental sound
on Sep 11, 2015 at 5:45:00 pm

I was assuming that you already knew that what you are describing is an "audio dosimeter" and they are available commercially. Here is an example...

http://www.amazon.com/Etymotic-Research-ER200-Personal-Dosimeter/dp/B00P9X7...


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