One of the problems with wildlife video photography is that you can get close to the animal with a telescopic video lens, but what about the sound? It's still far, far away.
Jerald Cogswell came up with a solution. He created a sonic telescope to grab sound and bring it as close to the user as the visual image. Biologists can also use this MEMS microphone to listen to insects and burrowing animals. The microphone can take the sound and match it to the proximity of the image.
Jerald Cogswell mounted a precision MEMS microphone in a satellite dish's focal point so it can feed its signal to an amplifier that enables simultaneous recording and monitoring via headphones.
That might be something I'll try Debera. I'm not sure how that would work but I'm into experimenting. Any references you can provide? The good news is that you can mount this microphone and amp in anything you want. With some circuit board layout it could be made smaller. I'm thinking of redeploying the circuit for other purposes.
Yes, Warren, unused dishes are plentiful. You can even find them in trash dumpsters. Mine was one that was left behind when I switched satellite providers. But I felt I needed to give a supply source for those who want something now. But, yep, why pay for it when you can find it free?
This is a creative device. The fact that hobyists can use these technologies in such a useful way is a great thing. There are a lot of mems devices available now, and with the other components that might make up a useful device the scope for creative development is wide open.
Using soundis a good way to find and identify wildlife as well. It is about this time of year that all the sounds come out.
I would think this is also usable in the movie industry. In many cases, it seems that movies are made with microphones on booms that only pick up the sound in the immediate area. That's especially true for nature documentaries, where the camera and sound equipment is often 100-200 yards away from the subject. Very innovative idea.
I was really impressed with the sound microscope modelling. The dishes are usually found in apartment dumpsters around the end of the month when people move out and don't want it anymore. I will look into the mems device itself, because I can think of some other applications for it. Great article.
Thanks, Jim S. If you build this amp I think you will be delighted with the sound quality. The sound quality of my video was compromised by the cheap voice recorder I was using. But through the Bose headphones, the noise level is inaudible and the sound is very clean; not surprising when you read the datasheet specs of the devices.
Since the article was written I have increased the output amp gain to 20 with excellent results. There are several benefits afforded by the balanced line architecture. Read the MEMS mic datasheet and application notes for tips on making the mic more directional by using an array of them. You could try mounting them in a conventional stethoscope. The MEMS mic's architecture will not give the "proximity effect" of other mics. Proximity effect is the boost of low frequencies when you talk close. This bass boost is used by late night DJs to get that crooning sound. Let me know if you find other uses. You could even use it for a singer's performing preamp if you shield the mic from saliva and dust.
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