Dave Moulton

I don’t know how many TV Technology readers know of Neil Muncy. However, it is highly improbable that any of us haven’t heard his work.

The protocol is for modifying the television audio signal to measure its magnitude in a way that more closely agrees with humans' subjective sense of loudness

Alert readers may recall that for the past year I’ve been devoting most of this column to the CALM Act and the related issue of audio levels and loudness in broadcast television audio.

We also seem to have fractured our physical audio delivery systems into four distinctly different genres, all served by the same HD digital audio feed embedded in our productions.

Their performance and effectiveness can be highly variable for a range of not-so-obvious reasons.

It seems appropriate to me that we go a little further with the discussion, simply to clarify what seems to be meant and desired in practice by A/85 and its authors.

Not all crumminess sounds the same.

24 dB below Full Scale (zero LKFS) is the new mandated nominal, or "target," level for audio broadcast.

We would like all equipment to play back at the same calibrated level, including in our viewers' homes. To achieve that, we use a protocol called dialnorm.

My measurements sought to examine the question of variance of audio levels between channels and how this variance has changed (or not) over time.

This process will have the effect of making your mixes clearer, more transparent, a little louder for a given maximum level and generally a little "nicer.

In this follow-up column I will reveal to you how to enhance and polish that sound once the warts are gone, or at least reduced.

I thought it might be nice to take a moment to consider the primary tool we use to cope with audio mayhem, the audio compressor.

Compressors go back and forth between the realm where the level change can occur to each individual sound and the realm where we are changing the overall level for a while.

Our perception of loudness varies as a function of amplitude, frequency, frequency bandwidth and time. It is a complex sensation.

One major determinant of timbre is the distribution of energy across the audio spectrum.

There can be hundreds of overtones present in a particular note or sound.

You may recall I've been ranting about variance in loudness levels on broadcast television for numerous years.

Stable, consistent and predictable bass is one of the hardest things to obtain in a monitoring situation.

As we've discussed, low frequencies don't do well coming out of small loudspeakers into smallish rooms.

A key ingredient of almost any successful stereo production

This is not easy to do, and impossible to do perfectly.

There are issues of dynamic range, maximum and minimum levels, subjective loudness qualities, spectrum and much more.