Australia’s television has some specifics for commercial advertising, some of these include decibel limits based on Rms levels and gain levels. There are problems involved with the current use of this but, we will read on that soon. LKFS is a relatively new term, which means “Loudness K-weighted relative to Full Scale.” It’s a scale for audio measurement similar to VU or Peak. However, rather than measuring gain, it’s measuring loudness. LKFS is based on the ITU-R BS.1770 Loudness Measurement Method. The loudness unit of LKFS is dB and is used the same way as a dB of gain. For example, a -15 LKFS program can be made to match the loudness of a -22 LKFS program by attenuating 7 dB. Incidentally, -22 LKFS is considered a Dialnorm of 22.
The Code of Practise contains provision which state;
- 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.
There are a few ways of measuring these values and limits. LKFS (Loudness L-weighted Full Scale) and LUFS (Loudness Units Full Scale) are measurements that are absoloute, depending on which broadcast standard is in use. They are identical but have a difference in total equal to 1db. the loudness target level could be e.g. -24 LKFS or -23 LUFS.
LU (Loudness Units) is the standard broadcaster’s target level rather then being -23 LUFS or -24 LKFS.
0LU limits have been placed on values for advertisement and programming. Below are some recommendations by TC Electronic on how to follow these guidelines.
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.
The commercial broadcasting standards for Australia’s ‘FreeTV’, tend to be focused on decibel limits. The loudest point in a show is the loudness limit for an advertisement. This has been an ongoing topic for debate as the transition from programmed television to advertisement creates a wall of noise which could potentially cause deafness to audiences watching.
There have been changes made and some new standards of broadcasting have been introduced to attempt to fix this issue. Australia currently uses standards system ‘OP 48’ which is what I was describing above. When a program reaches i’s loudest point, and advertisement comes in to take advantage of the loudness standards so that it can capture the listeners attention, but it gets to the point the the listener needs to rush to turn down the volume of their television sets. This is why ‘OP 59’ was issued in by The International Telecommunication Union or ITU which is referred to as ITU-R BS.1770, the current evolution of which is ITU-R BS.1770-3.
Using a meter that conforms to ITU-R BS.1770-3 you can actually get a quantitative measure of the loudness of a soundtrack. OP 59, like the US and European standards, specifically looks at (or listens to) the average or integrated loudness of the entire program . So if you were mixing a 30 second TV soundtrack you have to play the entire 30 seconds through the meter to arrive at your LKFS value, which for OP 59 -24LKFS.
OP 59 will likely address these common issues. Because we are now mixing to an average loudness, rather than a loudness limit.
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
Audio Loudness and the Calm Act, Dial Norm and LKFS. Retrieved 16 December 2015, from http://www.ensembledesigns.com/products/audio-loudness/