TAC System NML RevCon-RR ReviewPLUG-IN REDUCES AMBIENCE EMBEDDED IN RECORDED MATERIAL 10/25/2010 2:49 PM Eastern
One fundamental problem that has always plagued audio engineers is the detrimental impact of excessive levels’ reverberation on the intelligibility of recorded speech tracks. So what happens in a film or TV production when a particular recorded take is the “best” take, yet speech articulation is lost to excessive reverberation? You can try to fix it in post-production—maybe.
Removing excessive reverb from speech tracks is the aim of NML RevCon-RR, a Pro Tools Audio Suite plug-in designed by NTT Communication Science Laboratories for manufacturer TAC System. The company’s Website calls it the “world’s first plug-in for speech de-reverberation.” The only similar such product I’ve come across is the “De-Verb” MicroPlug from SPL, which offers a simple, single-knob solution for reducing the room’s role in a recording. On the other hand, NML RevCon-RR is designed specifically to increase the intelligibility of speech, and it does so by offering advanced controls and powerful processing.
The user interface of this Audio Suite–only plug-in is large and eye-catching. It doesn’t offer an overwhelming number of controls, but does provide some complex and truly unique means of achieving its goal and making the results sound better. The most apparent control is the largest knob in the window, which adjusts the balance of the original recording to the processed version. For quick and dirty applications, this might be enough to get the job done. However, the struggle here is walking the line between the desired effect and an unlistenable, digital-sounding outcome—and, of course, this outcome is dependent on the source.
As with any plug-in processor, the quality of the original recording plays a big part in the results of processing. In this case, noise in the track causes inaccurate detection of the actual reverb decay envelope. RevCon’s solution is to allow the noise to be analyzed and extracted before the de-reverberation processing is calculated, and then re-introduce the noise later to add realism. While RevCon’s NR toolkit is good, I obtained better results when using BIAS’ SoundSoap 2 for my noise reduction and then let RevCon apply the deverberation. After this, I used a long sample of ambience recorded before the voice to add as much as I needed for dynamics back into the mix from an extra track in Pro Tools. This was helpful in hiding the gating effect imparted by the processing and masking low-level sounds, which seemed to turn to artifacts very readily.
If the first approach falls short, you can apply more advanced controls. This is where the GUI’s large, visual readout displaying waveform envelopes and a spectrogram became useful. By toggling back and forth between the before/after views, the actual effect of removing decay is visually evident. The Attack Suppression control let me attenuate early reflections that were not reduced by the plug-in’s basic Reduction knob, while its Release Suppression control allowed me to tailor the cut-off of the reverb decay. With the proper balance of these controls—and just the right amount of the basic reduction—I was able to take dialog recorded in a variety of reverberant environments and successfully attenuate the echo to the point of improving dialog intelligibility.
DID IT DE-LIGHT ME?
RevCon does a standup job of reducing embedded ambience in a track, but not without some caveats. A fast machine with plenty of RAM is recommended when using this product, as processing on a slower machine is a bit sluggish. Also, the effectiveness of this process is heavily dependent on the quality of the audio.
Don’t expect that NML RevCon-RR can suddenly transform ADR sessions tracked in a shower stall and universally translate them for any physical space. Likewise, if you’re charged with the task of polishing poorly home-recorded music into a hit release, don’t expect that this plug-in can resurrect super-roomy vocals and make them sound like those recorded in a pro studio.
However, for well-recorded production sound that contains just a bit too much natural reverb to cut through the score and sound effects in the finished mix, RevCon-RR might be just the thing to help you create more distinguishable syllables.
Brandon Hickey is an independent engineer and film audio consultant.