Reading decibel levels in a waveform

[AGC]

I'm just beginning to try to learn Pro Tools, and one thing I can't figure out -- even after searching through the user's manual and the Pro Tools Visual Quickstart Guide -- is how to read the decibel level of a given sound.

I'm trying to compress the dynamic range of a simple voice track. I've been told to set the threshold to three to six decibels below the highest peak in the track. But I can't figure out what the decibel level is of the highest peak in the track.

I'm sure this must be ridiculously easy to do, but I can't figure it out.

Little help?

Thanks.

[Peter Groom]

I say that your ears are the final assessor. You cant have a numbers setting and just enter them. Fair enough people will through experience be able to put in values thatw will be their favourites, but ears and listening must be the final judge.
When numbers and stats in an audio chain become all thats needed, then sound engineers and dubbing mixers have effectively become accountants.

Peter

[AGC]

I say that your ears are the final assessor. You cant have a numbers setting and just enter them. Fair enough people will through experience be able to put in values thatw will be their favourites, but ears and listening must be the final judge.
When numbers and stats in an audio chain become all thats needed, then sound engineers and dubbing mixers have effectively become accountants.

Peter

Well, I don't disagree with you there. Still, I don't think it's too much to ask, in an audio program, to know what the decibel levels are.

[AGC]

Just use the meters

The track has one in the mix window

The meter in the mix window doesn't show the decibel level, as far as I can tell. I need to know that, in numeric form.

I did figure out one way to do it, and that's by using the Gain plugin in AudioSuite. You select any part of a waveform and the Gain plugin will give you the decibel reading of the peak in that selection.

[calacain]

Cmd+click the volume indicator to switch it from volume (level) to peak (in dB).

-kirk

[Mikeren]

The meter in the mix window doesn't show the decibel level, as far as I can tell. I need to know that, in numeric form.

I did figure out one way to do it, and that's by using the Gain plugin in AudioSuite. You select any part of a waveform and the Gain plugin will give you the decibel reading of the peak in that selection.

The tick marks on the meters are -3,-6,-12, etc., but they are a rough indicator at best.

You're right on about using the gain plug-in for a forensic peak read. I'll read the whole track (not a section) to check for overs and such. Just avoid the temptation to manually 'normalize' every track. 24bit is quiet enough to record at -6 or -12. PT's mix bus will like you for it.

[Mikeren]

Oh shoot. I missed your original point.

Chris(binary) said it all (and well) with regards to compression.

MR

[AGC]

I would suggest that the gain reduction meter is more relevant to you. It will give you a clear indication of how much of the signal is above threshold. Pull down the threshold and you'll see the compressor start to work. 3 - 6dB of reduction is a good starting point. The ratio setting will determine how much compression is applied. Attack will determine the speed at which the compressor reacts. Release is how long it waits before restoring full gain after the signal falls below threshold.

A helpful technique when learning is to pull the threshold right down, say 12 - 18dB of gain reduction. This is pretty severe but it will help you hear what is going on when you change attack/release and ratio settings. Bring the threshold back up when you're done. Messing around with extreme compression helped train my ears to hear much more subtle amounts of gain reduction.

Although compression is a purely scientific process, applying that science effectively is an art form. Practice is the only way to become good at it. Don't worry too much about the numbers.

Chris

Thanks. That's exactly what I want to do -- mess around with this stuff and get a feel with my own ears of what it's capable of and what I need. Can you point me to the gain reduction meter? I can't find it. It it a plugin?

[AGC]

Never mind -- I think I found it. Is it the Compressor plug-in in AudioSuite? That has adjustments for threshold, ratio, etc.