Dolby LM100 Tackles Loudness Problems
September 17, 2008
For a sound designer like me working every day on "sound for pictures" projects, loudness inconsistency in broadcasts is a real issue and one which we at Fox Channels Italy have aggressively addressed in the past few years. This was especially true as we moved into HD broadcasting with 5.1 audio, so a tool like the Dolby LM100 Broadcast Loudness Meter has really had a significant impact on the work we do.
We installed the first one in 2006 when we launched our two HD channels: National Geographic Channel HD and Next:HD. At the time, we upgraded our Pro Tools suites to full HD and with our other Dolby hardware designed for encoding Dolby E streams, the LM100 was the natural choice to give us the loudness measurement and control we desired. What's more, we knew it would match perfectly with the other Dolby equipment we had installed.
I can't stress enough how important loudness consistency is for audio. Television viewers shouldn't have to change volume in between programs or when switching channels. However, with the peak metering previously used sound levels may not have exceeded the maximum permitted signal peak levels, but perceived sound levels were often remarkably high, especially during interstitial breaks. At Fox Channels Italy we aim to offer a non-stop pleasurable TV experience for our viewers, and loudness metering has contributed very much to that. In my mixes I'm no longer constrained by signal peak levels or hampered by over-compression. The LM100 allows me to control and maintain the program loudness within the satellite broadcaster's recommended levels, while keeping its dynamic range at the level I like. It gives me much greater flexibility so I can ensure that a broadcast program sounds as I want it to.
In addition, due to the small audio dynamic range in television and the fact that viewers use speech levels to adjust volume, I found the "Dialogue Intelligence" feature very effective. The meter guarantees a reliable overall loudness reading. This ensures speech levels in my mixes are always aligned with the platform target loudness level and that the program dynamic range will be maintained within a comfortable range.
Recently, Dolby released a new firmware version complying with the ITU Recommendations BS.1770 and BS.1771 that specify the algorithms that should be used to measure audio program loudness. This will help in exchanging material among broadcasters, and will be especially important as governments and standards bodies in Europe demand action on loudness inconsistencies.
The Dolby LM100 proved an easy choice for us, especially as Dolby Laboratories and their distributor, Audio International SRL, worked so closely with us in setup, training and familiarization with the capabilities of the entire Dolby E family.
In the end, what we want to do is provide the best quality experience for the TV viewer and with a tool like the Dolby LM100, issues with loudness inconsistency are becoming a thing of the past and the overall audio quality has benefited tremendously.
For additional information, contact Dolby Laboratories at 415-558-0200 or visit www.dolby.com.