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Subject:recording in large lecture hall
Posted by: choy
Date:11/12/2003 1:31:54 AM

I do recordings of lectures using hand-held recorder in large lecture halls and auditorium where the speaker often use PA system. The voice results in artifacts (but not echo), or should I call it "mirror effect" (if I underestand it correctly from the description in SF)? While SF has tool to create the "mirror effect" in large hall, I want to get rid of this artifact so the audio become more crisp. Any advice is appreciated.

Subject:RE: recording in large lecture hall
Reply by: Rednroll
Date:11/12/2003 7:17:16 AM

The best you could do is to use some Eq and boost the presence range (3.5Khz to 7.5Khz area...try 4.5Khz as a start with a Q of 1). You might also try using a lowend shelf and reduce from 175Hz and below, to get rid of some of the boominess.

These are band-aids at best. This falls under one of the golden rules of recording: "GARBAGE IN EQUALS GARBAGE OUT"

Subject:RE: recording in large lecture hall
Reply by: DKeenum
Date:11/12/2003 12:20:14 PM

You may be describing what is refered to as slap back echo (old elvis recordings) or early refections. You can add these, but they are hard to take away. Sometimes you can use a gate or expander to soften their effect, but they are hard to deal with.

Subject:RE: recording in large lecture hall
Reply by: Geoff_Wood
Date:11/12/2003 5:39:23 PM

Your best bet is to address the problem at source - a higly directional mic will reduce pickup of slapback echos. Apart from that, noise gating is about all your can do, which can sound pretty unnatural in itself.

You could try suggesting a better venue ...

geoff

Subject:RE: recording in large lecture hall
Reply by: rraud
Date:11/12/2003 7:45:48 PM

To reinerate on what Geoff said, "Your best bet is to address the problem at source."
ie: Get the microphone as close to the sound source as possible.

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