Removing reverberation is very difficult and not possible with readily available tools. It may help to pass the audio through a gate which attenuates low level sounds.
Thanks for the info Peter. I found in the "dynamics" effect a "auto gate". I checked the box, can't tell what if any effect it has on the audio until I run it through our sound system. I haven't dealt with audio effects much so any suggestion is appreciated. Thanks for the post.
If you are not doing so, I suggest you monitor your audio work with a decent pair of headphones. If there is reverb in your audio it should be clearly heard, together with any artefacts you might introduce with too much gating.
Over in the Audition forums there's a couple of broadly relevant FAQs on this subject -
One of the suggestions via Ozpeter's links was to model the impulse response from speaker to microphone in the reverberant environment. This is roughly what Gloftis would have to do:
Put the speaker back in exactly the same position in the original room with the same lapel mic in exactly the same position. Add a small high quality microphone close to the lips of the speaker. It would have to be so close that the reverberation was negligible and positioned so that breath pops didn't occur. Then get the speaker to say or read a few minutes of speech, and record the output of both microphones simultaneously. From this, the room acoustic and lapel microphone response as a whole could be computed (a black box filter response). The inverse response then needs to be computed, and you hope that such a filter is stable (not guaranteed). Then pass the reverberant speech through this inverse filter and voilà!
Another solution suggested was expanding the low levels downwards. That is essentially what I suggested in my first post. Expansion should be less obtrusive than gating (hard on/off).
Finally, the most straight forward method, if practicable, is to re-record the voice material in a non-reverberant environment. He/she could listen to the original speech and read out the material in synchronism, with the same mannerisms, to preserve lip-synch.
During the interview, I was using a good set of headphones and the audio I was hearing sounded perfect, crisp and clear. That's what's so puzzling about this problem.Sounds good on the computer but sounds awful when played through a digital console on suspended line array speakers in the 1200 seat auditorium. Go figure! Thanks
I think you might need the advice of some audio savvy people on site to resolve this one. Try to pinpoint where the problem lies. Is it the PA system or your recording? Do any other recordings with that mic in a definitely non-reverberant environment also sound reverberant? A cheap microphone with sharp resonances may give colouration like reverberation.
If the original audio sounds OK, then the problem is probably with the acoustics of the playback environment.
Just because the audio is being routed through a 'digital console', it won't change the laws of physics! If the playback auditorium has a reverberant characteristic, then any audio being reproduced in that area can 'excite' this reverberation, and above a certain volume level the resulting reflections can cause the problem you describe. In your example it sounds as if the spoken audio is loud enough to excite the reverberation, and create troublesome reflections, whereas the background music is not.
The traditional way of solving this problem is to reduce the audio level, so that it doesn't excite the reverberation, but this usually requires that more loudspeakers are distributed, to cope with the lower volume level.
In recent years, some loudspeaker manufacturers, like 'Intellivox' for example, use advanced DSP processing in conjunction with adjustable line source arrays to help combat the problem. How successfully, I'm not sure, but I have heard good comments of that type of installation fitted into railway stations, for example.
It's very expensive though!
Make sure the auditorium system is not introducing any reverberation or surround sound processing. And what you are describing sounds a lot like a phasing issue.... a stereo source combined into mono with the phase reversed on one channel. Was your original sound track mono? And did you by any chance apply any sort of surround sound processing?
If the sound system is actually programmed to add reverberation, then that is definitely going to add to the problem. I can't see that phase reversal would though. It might reduce the bass response a bit, but it's unlikely to affect the reverberation problem.
Surround sound processing might - especially if any digital delays are involved.
I think this is just an example of the traditional problem that has plagued public address in large internal spaces for years. If the direct to reveberant ratio is too low, you won't understand the speech!
You can Google 'direct to reverberant ratio' for a whole load of data on the problem. Some of it is readable!!
In large listening spaces such as a sound shell with multiple speaker clusters, an electical delay is sometimes introduced in the feed to the speakers closer to the audience to compensate for the acoustical delay from the speakers further away. Without the delay the speakers would give an echo sound. Reverberation is multiple echos. If Gloftis's church has multiple speakers and no compensating delays then reverberation might result.
Reverberation is indeed multiple echos.....thousands and thousands of them! That is not quite the same thing as delay line correction for multiple source control.
You are of course absolutely right in describing the requirement for timing correction in different loudspeaker locations, so that an audience can hear an apparent single source response, where otherwise signal delays would cause several 'sources' to be sequentially heard. Irritating, but not reverb!
The reverberation problem comes from reflected sound, not direct source sound, and if there is too high a level of reflected sound, to direct sound content (direct to reverberant ratio), then it all becomes an unintelligible 'mush.'
I had the exact same problem using the internal laptop microphone. When I went to a desktop microphone all reverb was gone. I also selected the muted playback option when recording.
It seems some microphones are more prone to this issue than others.
Hope this helps.
Have you looked into microphone options in this regard now 2015 and then 2008 when this thread was created and written to last?
I have not, just asking.