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stevegong
2010-05-14, 11:02
I want to make binaural (http://en.wikipedia.org/wiki/Binaural_recording) audio recordings.

I have a pair of headphones, but when I plug them into the line in jack of my MacBook Pro, the input levels are very low, even if I crank up the gain all the way. I presume this is because my headphones are not providing an amplified audio signal.

So what can I do about this?


On another note, I've just ordered this portable recording device (http://www.wired.com/reviews/product/pr_olympus_ls11). How do I figure out if this device supports plugging in headphones into the mic jack and whether it is able to amplify the signal?

Thanks.

Bryson
2010-05-14, 11:18
While a pair of headphones will theoretically work as a pair of microphones, they won't work well. Sound quality (and level, as you've noticed already) will be extremely poor.

I did a project a few years ago that involved binaural recording and we used a polystyrene head designed for storing wigs with two holes drilled in it and a couple of condensor mics embedded in it. Sounded great.

stevegong
2010-05-14, 11:20
What kind of mics did you specifically use? Do I just need condenser mics, and that will yield a more powerful signal? What recording equipment did you use?

Can I see your project?

I seem to think part of the reason is that line-in jacks need amplified signals, whereas mic jacks can take anything.

sunrain
2010-05-14, 12:29
Go here:

http://www.soundprofessionals.com/cgi-bin/gold/category/110/mics

They have head-mounted binaural microphones to fit many budgets. They've been selling to the concert bootleg crowd for years, so a lot of them are made for unobtrusiveness.

Bryson
2010-05-14, 14:28
What kind of mics did you specifically use? Do I just need condenser mics, and that will yield a more powerful signal? What recording equipment did you use?

Can I see your project?

I seem to think part of the reason is that line-in jacks need amplified signals, whereas mic jacks can take anything.

Condensors tend to be better for "ambient" noise, rather than dynamics that tend to be more useful for close-micing an instrument or voice. We used AKG 300Bs with CK91 capsules, although that was more an artifact of what we had in the mic cupboard rather than an specific choice. Recording went straight into the laptop via a MOTU interface. Portability, obviously, was low. It needed it's own AV cart and a tall mic stand for the "head".

You can see the project...but...you'd have to go to DanceCity in Newcastle-Upon-Tyne and use the "jukebox" in there. It's not online. ;)

Mic level and Line level are miles apart. Line level is -10dBV*. Mic level is -60dBV. dB is logarithmic, so there's a lot of difference between those two... ie: it's a case of what the input is "expecting". Plug a line-in source into a mic input and you'll peak the crap out of it. Plug mic level into a line-in and you'll get virtually nothing. Sometimes equipment has built in switchable "pads" that allow you to deal with both on the same input, although I don't see any evidence of that on the unit you're buying.

The link that Sunrain gives looks promising for a low-fuss solution - I would be concerned about handling noise though.

Short answer; use real microphones. Headphones aren't microphones.






* = Or +4dBu. But then we have to mess around comparing different units.

Bryson
2010-05-14, 14:35
Feeling Rich? ;)

http://www.neumann.com/img/photosGraphics/Zooms/KU100_Z.jpg (http://www.neumann.com/?lang=en&id=current_microphones&cid=ku100_description)

A snap at....$8000