Loudness Control: 3 Things to Watch

Loudness Control: 3 Things to Watch

DimensionThreeLoudnessHere are three critical things to watch on the mixing desk and what you need to know about them for effective loudness control.

1. VU indicator. The VU meter (now in digital bar graph form) has been around for 80 years for a reason. It’s predictable, with predictable integration times and predictable release times so you can predictably read volume units. Remember it is an averaging meter and the peaks are far higher than indicated. For this reason you can expect to have about 20dB of audio headroom above 0dBVU to encompass them.

2. Peak level indicator to read the transient peaks of the signal. This indicator tells you if peak levels are in danger of overloading the dynamic headroom limitations of the console. The clipping point is usually at 0dBFS. “Clipping equals distortion, so don’t go there unless you absolutely have to. Stay within a reasonable gain structure that is not going to cause distortion,” says Steve Dove, Wheatstone Minister of Algorithms. Peak signal levels run usually at or above -20dBFS, with transient peaks kicking up to about -6dBFS occasionally.

3. Loudness indicator for compliance with the ITU BS.1770-3 and similar television loudness standards. This indicator came about initially in response to the need to assess and regulate the loudness of adverts compared to regular programming. The Loudness Unit Full Scale (LUFS) or Loudness K-weighted Full Scale (LKFS) measurement shows the averaged loudness level of audio over time, usually much longer than that of a VU meter. “Ideally, you should measure at a very long integration time (30 seconds), because that would be most accurate. But if you need to know fairly quickly if you’re going to be over the top or too far under, then you might want to go for a shorter integration time of, say, 3 or 10 seconds,” says Dove. The average loudness target level is -24 LKFS or -23 LUFS, depending on your location. By the way, you can’t miss this on a Wheatstone audio console – the LKFS/LUFS numbers are two inches high on the display screen. One LU (loudness unit) is equivalent to 1dB, so there's a direct correlation between how far the meter says you're over/under and how far you move a fader to compensate.

Site Navigations