Audio HDR?

[egproductions]

I was thinking...

its probably already a method of recording but are there microphones that are dedicated for catpuring low to mid frequnces and microphones that are good for mid to high. Could you then later mix the two tracks for really excellent audio? Maybe people already record with mics that are better for one range or another and mix them. But I am kind of thinking like the equievelent to a prime lens that can produce excellent quality audio but has a fixed focal length/frequency.

 

[Alex H.]

In a way, this does happen.

For instance, micing a guitar cabinet with two mics: a dynamic centered on the cone, and a condenser off-center. The two can be mixed together to bring out some very nice sound from the electric guitar. The mics may each be EQed to accentuate their individual strengths, but they're both still using their full responses. The same can be done for kick drum, and AT has even built a mic just for this that houses both a dynamic and a condenser element in one chassis.

http://www.audio-technica.com/cms/wired_mics/4359efa46266c7e9/index.html

And also using the drum kit as an example, you'll have a mic that is adjusted specifically for the kick, one for the snare, at least one for toms, and then a couple of overheads that fill out the sound and pick up the brass as well. Often, in recording, there's also a room mic (usually an omni) that is set a few feet in front of the kit. Each mic is EQed to accentuate its individual drum or purpose, and they are all mixed to create a full sound. And I guess you could really use this analysis for something as large as an orchestra, where sectiones are miced individually and then mixed together.

Even in on-camera dialog, you'll often hear the mix between a couple different sources. The actor's dialog may primarily come from a lav, but a little signal from a boom mic (shotgun or hyper) may be mixed in under that to give some depth to the sound by adding a little bit of the room/environment.

But dual-mic techniques don't generally "expose" one for only lows and low-mids and the other one for high-mids and highs. They take two mics in their full responses and blend them. It's a much different practice since sound waves don't interact with mics the way light waves do with lenses. You have to be careful mixing two mics in order to avoid phase cancellation. This is not at all like HDR compositing.

The idea of using one mic to record low and one to record high just won't work so well, if we're talking about a single source especially. There will be problems with the crossover frequencies that will keep it from being a really good, wide-spectrum sound. Truly, the best way to get a full spectrum in sound recording is to invest lots of money into a mic that can record a full spectrum with as little coloration as possible.

Add to that the fact that you'd be adding a lot of unnecessary work in post.

 

[Brad S.]

Though I've never done this myself, I've seen music engineers rewire speakers so that they act as microphones and use them to record the ultra low frequencies of a kick drum. A dynamic microphone is essentially the same as a speaker, except it's wired in reverse. I don't know the technical details of this so maybe one of the other folks on this forum can chime in on how this works.