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May 5, 2011

by The Conversations Network

What is The Levelator®?

Do you believe in magic? You will after using The Levelator® to enhance your podcast. And you’ll be amazed that it’s free, now even for commercial use.

So what is The Levelator®? It’s software that runs on Windows, OS X (universal binary), or Linux (Ubuntu) that adjusts the audio levels within your podcast or other audio file for variations from one speaker to the next, for example. It’s not a compressor, normalizer or limiter although it contains all three. It’s much more than those tools, and it’s much simpler to use. The UI is dirt-simple: Drag-and-drop any WAV or AIFF file onto The Leveler’s application window, and a few moments later you’ll find a new version which just sounds better.

Have you ever recorded an interview in which you and your guest ended up at different volumes? How about a panel discussion where some people were close to microphones and others were not? These are the problems the post-production engineers of Team ITC here at The Conversations Network solve every day, and it used to take them hours of painstaking work with expensive and complex tools like SoundTrack Pro, Audacity, Sound Forge or Audition to solve them. Now it takes mere seconds. Seriously. The Levelator® is unlike any other audio tool you’ve ever seen, heard or used. It’s magic. And it’s free.

When we developed the IT Conversations component-based show-assembly system, we realized all the components had to be of the same loudness or the results would sound awful. We limped along for many months using the RMS normalization functions in various applications, but the results weren’t satisfactory and it required tools and skillsets that some of our post-production audio engineers didn’t have. One of our best engineers, Bruce Sharpe, offered to write a standalone software RMS normalization utility, which we’ve been using as part of our production system CNUploader since 2005.

The CNUploader’s normalizer acts similar to an intelligent RMS-based compressor/limiter combination, and it therefore affects primarily the short-term (transient) sounds and the long-term overall loudness of the file. It doesn’t make the kind of adjustments that a skilled audio engineer can perform in software or at a mixing console, riding the levels up and down to compensate for medium-term variations.

There are some hardware devices such as various AGC (automatic-gain control) components that can do moderate leveling, but since they have to operate in real time (i.e., without look-ahead), they can’t do much. And they aren’t cheap, let alone free. Even a skilled human can only react to changes unless s/he is lucky enough to be present during a recording session and can use visual cues to anticipate coming variations. Software can do better by performing multiple passes over the audio, generating a loudness map of where the volume changes. (It’s not actually that simple, but the metaphor is helpful.)

Bruce, with help from his son, Malcolm, had proven that he knew how to tackle these problems in ways that no one else anywhere in the audio/software industry has done to date. So we asked him, “Bruce, do you you think you can write a leveler that corrects for medium-term variations in loudness instead of the short-term and long-term variatons processed by compressor/limiters and normalizers, respectively?” Bruce and Malcolm took on the challenge, and eight months later we began testing The Levelator®.

You’ll believe in magic.

Do you believe in magic? You will after using The Levelator

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