best mike to pick up audible voice in a classroom

[Maximo Salaberry]

I'm looking for the best mike (hot) that could pick up voices in a classroom. The goal is to transcribe dialogue only. The camera would be placed in a corner fo the room with a wide angle. This is the only non-obtrusive option for the placement of the mike.

With thise constraints in mind, I was thinking the ROde videomike could be an option but considering that this is indoors I wonder it other mikes could be better for the purpose of obtaining audible (not broadcast quality) audio.

thank you

maximo

[David Tamés]

Originally Posted by Maximo Salaberry

I'm looking for the best mike (hot) that could pick up voices in a classroom. The goal is to transcribe dialogue only

I've done lots of transcription of interviews and one thing that I find makes it easier, especially if there are multiple speakers, is record the dialog in stereo. This makes it easier to hear what speakers are saying and to separate their speech from the ambient noise, especially when there are several of them.

What kind of audio input does your camera have, 3.5" mini w/ plug-in power or XLRs? I use the little T stereo mic that came with my MicroTrack 24/96 compact fash recorder for stuff like this.

[Maximo Salaberry]

I would have both 3.5 input from camera and beachtek DXA2s available (no phantom though).

For reference I already have a RODE NT-3 hypercardioid (but I think it is not hot enough), a RODE videomike, and an Electrovoice RE-50 ND/B. Would any of these work best? Or should I consider another alternative?

thank you

[Ralph Keyser]

You mentioned the camera placement, but where will the mic end up relative to the speakers?

Also, when you use the term "hot", do you mean level of output signal from the mic relative to the input?

The RE-50 is a great dynamic mic, but really needs to be close to be effective. I probably wouldn't consider it for this application.

[David Tamés]

Given you already have a Rode NT3 hyper-cardioid condenser microphone and the option of working with it's own source of power from an internal 9V battery, this might be the one to use, getting it as close to the speakers as you can, and since this is just for transcription, as long as you hear the speakers clearly, you'll be OK. Crank the input gain on the camera and take a listen with closed-ear headphones to determine if what you're getting is sufficient for your needs.

[Maximo Salaberry]

That's my major constraint: I need to position the camera (and mike on top of it) in a fixed location where it can "see" the whole classroom. So distance mike-speaker will vary from about 10 feet to 30 feet.

However, as long as it's audible, it's ok for my purpose. Background noise is unimportant as long as the dialogue is audible.

So, obviously I can crank up gain, but then the only other variable I'm trying to determine is: Which is the best mike to work with? Would the Videomike be better than the NT-3 (despite it sounding a bit more hollow)?

thank you for all your responses.


maximo

[David Tamés]

Originally Posted by Maximo Salaberry

Would the Videomike be better than the NT-3 (despite it sounding a bit more hollow)?

If the video camera's mic is stereo, then the localization that comes from a stereo recording might help with improving the intelligibility of the dialog. Experimentation is one of the best ways to figure out this audio stuff, since it's all so aural, you have to hear it and "see."

[Stu Holmes]

Originally Posted by Maximo Salaberry

variable I'm trying to determine is: Which is the best mike to work with? Would the Videomike be better than the NT-3 (despite it sounding a bit more hollow)?

I would say, that if you're not goiung to use the internal omni mic, then for sure the NT3 would be better than Videomic. Videomic will be too directional - you've got a big classroom and if the mic is fixed it'll work GREAT for people roughly in front oif it, but far less well for people to the edges.
I think thje best place is to mount it in centre-line of room, highish up (say on top of tall mic stand) pointing down centre of room towards the students. Ramp up the gain, - should pick up everyone no problem i'd think without any re-orienting of mic.

[David Ennis]

I trust that the camera postion will be in a front corner facing the students. I shoot lessons for teacher portfolio submissions required in my state. I once shot from the rear to minimze privacy concerns, and it was a mistake in terms of intelligibility.

The use of stereo for increasing intelligibiltiy as mentioned by David hadn't occurred to me--iin terms of tonal quality it's usually inferior for dialog, but that's not the concern here. If I get a chance I'll try a test tomorrow. I have a Rode VideoMic, a Sony ECM-MS908C stereo mic and a Sony ECM-DS70P stereo mic (possibly the "T" shaped mic David referred to earlier), and some excellent isolating ear canal phones.

[Michael Wisniewski]

Could you get permission for 2 NT3s spaced out on mic stands? It's still not great, but it would be much more decent.

Or how about a mini disc recorder with the NT3 or lavalier to get closer to the speakers?