Following Adam Taylor’s question, which I covered in yesterday’s podcast, the guys at Nugen Audio have given me permission to post a video I made for them in which I show how I use their VisLM Loudness meter in my normal audio post production workflow.
Also I thought it would be useful to unpack some of the terms used in loudness metering so any good loudness meter should display at least these four measurement criteria….
Momentary Loudness (often described as ‘M’)
The Momentary Loudness measures a moving 0.4 second window of the programme and is then displayed by the meter. In the case of the Nugen Audio VisLM it is the vertical meter, other plug-ins display ‘M’ differently.
Short-Term Loudness (often described as ‘S’)
The Short Term loudness measures a moving 3.0 second window (this is often called integration where the meter produces a loudness figure for a specific window length) and should update the display at least 10 times a second. On the VisLM this is diplayed in the box labelled Short Term and also as a moving pointer on the vertical bargraph display and this is also what produces the histogram trace on the VisLM.
Integrated Loudness (often described as ‘I’)
This is the overall figure given for the complete programme and this value should be updated on the display at least once per second. On the VisLM this is displayed in the Integrated box. This is the figure that should be -23LUFS for the EBUR128 spec for Europe and -24LUFS for the ASTC A/85 spec for the US.
Loudness Range (often described as LRA)
This measurement gives a measurement to describe the dynamic range of the programme. This is helpful when mixing as we now have a consistent measurement for dynamic range. On the VisLM is is displayed in the Loudness Range box.
Because with the loudness specs we no longer need to work to a peak level spec measured with a quasi peak meter like the BBC PPM we do need to know where the peaks are and also we need to know where the true peaks are as there can be a higher peak level between two samples that can be up to 6dB higher. So any decent loudness meter should also include a True Peak meter as the R128 spec allows True Peak level up to -1dBTP (ATSC A/85 specifies -2dBTP). In this context we use the TP descriptor to specify that we are measuring true peaks rather than sample peaks which we would describe by dBFS. When I made this video Nugen Audio hadn’t made their new ISL True Peak limiter but this is now my preferred true peak limiter.
30 day demo
If you want to tryout a loudness meter then you can download a 30 day free trial of the VisLM from the Nugen Audio site.