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Best Microphone for an acoustically harsh environment?

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Best Microphone for an acoustically harsh environment?

Postby StrykerTim » Wed Feb 06, 2013 3:48 pm

I have a very unique scenario that I would like some professional input on. I work for a medical manufacturer who manufactures video and audio routers for operating theaters. Traditionally we have used headworn / lapel mics to grab a surgeons voice and minimize ambient noise. Recently there has been a huge increase in the number of surgeons requesting "open mics". As you can imagine, an operating room will be very difficult to mic. All surfaces are non-porus, HVAC function is elevated to provide positive pressure, and anesthesia equipment is constantly providing various alarms and med gas noise. We have tried shotgun mics with limited success. The problem withthe shotgun mic is that the surgical team moves around constantly which makes it difficult to "aim" the mic correctly. I am hoping someone may have some good suggestions on commercially available microphones or signal conditioning equipment that may help.

Thanks in advance for any help you can offer!

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Re: Best Microphone for an acoustically harsh environment?

Postby Hugh Robjohns » Wed Feb 06, 2013 4:48 pm

There are some effective noise reduction systems -- the CEDAR DN1000 and related models, for example -- that some broadcasters use in situations involving high ambient background noise. However, the results vary wildly depending on circumstances and the boxes aren't cheap.

Close miking -- headworn or lapel mics -- is the best bet. Get the mic as close to the source as possible, maximising the direct sound and minimising the ambient sound. Always the best solution.

Gun mics have higher directivity and so can be placed further away for the same ambient noise level as a less directional mic placed closer, but the difference in distance is no more than a factor of 2. So in reality, with moving ssound source targets, the only way to make gun mics work is to have someone move them -- which is why TV and Film have 'boom swingers' to do the job.

I know lots of sound recordists that have worked on medical TV programmes involving operating theatres, and lapel mics (the look of headset mics being unpopular with the directors) or actively positioned mics on booms are the preferred solutions.

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Re: Best Microphone for an acoustically harsh environment?

Postby StrykerTim » Thu Feb 07, 2013 3:32 pm

Thanks Hugh! It looks like Cedar has a pretty nice product line. I think we will look into the "DNS 8 Live", maybe it will be a better performer than the Polycom Vortex or BiAmp Nexia products. I know this sounds a little bit like science fiction, but do you have any experience with the "throat mics" similar what military personnel may wear. I admit I have only seen them on TV but they do not look like props. A web search only reveals a few actual products. It seems like a great idea if you could utilize smaller transducers to pick up voice quality audio. I think the reduction in fidelity might be a good trade-off for the ability to speak relatively quitely ann still maintain a high degree of intelligibility. Thanks again for the response!
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Re: Best Microphone for an acoustically harsh environment?

Postby Hugh Robjohns » Thu Feb 07, 2013 3:54 pm

StrykerTim wrote:do you have any experience with the "throat mics" similar what military personnel may wear.


Some experience. They are useful for hands-free communications purposes in noisy environments, but the the quality of the ones I've tried (admittedly a decade or two ago) was very poor in comparison to 'normal' broadcast-standard voice quality. They are, in essence, 'contact mics' -- and the throat doesn't make a very good sounding board!

However, I understand that there aer some throat mic designs now available for the iPhone and some internet gaming consoles, so maybe the technology is getting better... or at least cheaper!

Probably worth a try for your application, but i have no recommendations, I'm afraid.

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Re: Best Microphone for an acoustically harsh environment?

Postby John Willett » Thu Feb 07, 2013 8:20 pm

StrykerTim wrote:I have a very unique scenario that I would like some professional input on. I work for a medical manufacturer who manufactures video and audio routers for operating theaters. Traditionally we have used headworn / lapel mics to grab a surgeons voice and minimize ambient noise. Recently there has been a huge increase in the number of surgeons requesting "open mics". As you can imagine, an operating room will be very difficult to mic. All surfaces are non-porus, HVAC function is elevated to provide positive pressure, and anesthesia equipment is constantly providing various alarms and med gas noise. We have tried shotgun mics with limited success. The problem withthe shotgun mic is that the surgical team moves around constantly which makes it difficult to "aim" the mic correctly. I am hoping someone may have some good suggestions on commercially available microphones or signal conditioning equipment that may help.

Thanks in advance for any help you can offer!

Tim Frye
Stryker - USA

The solution may be the Gefell KM 907.

Image

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This has a cardioid response in the horizontal plane but a very narrow vertical angle.

As the mic. is about $12,000 in the USA, it may be an idea to hire rather than buy.

But it works very well in acoustically nasty environments and still works with people moving around.
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Re: Best Microphone for an acoustically harsh environment?

Postby Guy Johnson » Thu Feb 07, 2013 8:59 pm

A Bose stick in 'reverse'.
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Re: Best Microphone for an acoustically harsh environment?

Postby Hugh Robjohns » Fri Feb 08, 2013 10:27 am

John Willett wrote:The solution may be the Gefell KM 907.


I doubt it, personally, because while it has very narrow vertical directivity, it is still very broad horizontally and I think it would be difficult (if not impossible) to exclude all the noises sources the OP describes.

It is a very clever mic, though, and there are certainly some applications where it does a fantastic job. I reviewed the original version for a broadcast magazine HERE a few years ago.

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Re: Best Microphone for an acoustically harsh environment?

Postby StrykerTim » Fri Feb 08, 2013 1:47 pm

It does look like a very cool mic. The problem is (jsut to make thing s bit more complicated)that we need it to mount on a wall or ceiling mounted boom. We do this to try and keep it out of reach of the cleaning staff who love to spray everythign with a mixture of either bleach or alchohol. I will check out the companies website. We can definitely use a microphone like this one in conference room settings or possibly even surgeon dictation.

Thanks again for all the help guys! I think I will order one of the cheaper "throat contact microphnes" and see what the verdict is. I agree with Hugh that the poor quality might be an issue since we use alot of voice recognition in surgery. I will keep everyone updated!

Thanks again!

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