In Australia There are code’s and standards that set the recommended loudness levels (db) for commercial advertising on Tv. These code’s and provisions limit peak volume levels and Rms volume levels to make programs and advertisement adjacent in volume.
The Code of Practise contains provision which state the following
- 1.11 Commercials must not be excessively noisy or strident;
- 1.12 Licensees must do everything reasonably possible to ensure that commercials do not sound louder than adjacent programming;
- 1.13 Studio transmission must not be increased from normal levels during program breaks
- 1.14 A licensee shall be deemed to have complied with Clauses 1.11 and 1.12 provided it ensures that the relevant requirements of Free TV Australia’s Operation Practice Note on Loudness of Advertisements, as amended from time to time, have been met. This requirement is satisfied if a person submitting a commercial certifies to the licensee that all requirements of the Operational Practice Note on Loudness of Advertisements concerning compression, limiting and equalisation have been met.
Programming tends to have a large dynamic range as it is subversive especially if you are watching a drama movie as audio may be very quite to portray emotions on screen. Advertisement on the other hand is optimised to be as loud as possible using FX like multi-band compression, reverb and EQ to grab the audiences attention.
The problem is volume and loudness are perceived differently. Volume is accurately and objectively measured using peak’s in amplitude. Loudness however is subjective and is measured using rms. rms (average) is a closer representation of what the human ear can hear. Rather than audio being measured from sample-peak level, K-Weighting is applied to each audio channel to bridge the gap between subjective and objective volume levels. This basically means that volumes between programming and commercials with be closer in perceived volume levels.
There are three different ways of measuring loudness that you need to be aware of. While very similar, there are some small differences between the measurement methods.
LKFS (Loudness L-weighted Full Scale) and LUFS (Loudness Units Full Scale) despite the different names are actually identical and are equal to 1db. LKFS/LUFS is an absolute measurement and depending on which broadcast standard is in use, the loudness target level could be e.g. -24 LKFS or -23 LUFS. LU (loudness units) is now the standard broadcaster’s target level rather then being -23 LUFS or -24 LKFS, The new standard is 0LU.
In Australia a 0LU Limit have been placed on values for advertisement and programming. Other limits and recommendations for audio mixing and processing are listed below.
Compression: The Appropriate use of compression should be used throughout the production process to constrain the dynamic range of vocals,music tracks to produce a consistent sound track
Audio Limiting: is a useful tool that prevents distortion in audio systems. When recording a television commercial limiting must not be used for producing excessively noisy or strident material.
Spectral Manipulation (Equalisation): Like Audio Limiting (Spectral Manipulation) must not be used for the purpose of producing excessively noisy or strident material. Equalisation is a very basic tool and is often used in audio production, but care should be taken to avoid excessive amounts of equalisation that could cause overloading of broadcast audio chains.
Milne, S. (2012). OP 59 and Loudness Standards for Australian TV | Sound and Code. [online] Sandymilne.com. Available at: http://www.sandymilne.com/op-59-and-loudness-standards-for-australian-tv/
Tcelectronic.com,. (2015). Loudness Explained | TC Electronic. Retrieved 16 December 2015, from http://www.tcelectronic.com/loudness/loudness-explained