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Re: Loudness (ITU BS 1770 / EBU R128) Normalization
It would be worthwhile for people to search old threads on this subject. As I have posted here before, the choice of -23LuFS/LKFS or thereabouts in the various loudness standards was based on the levels used in professional television broadcast applications (for which the standard was written and intended). Professional broadcast audio levels in the plant are very much lower than the levels that have typically been used for digital consumer products like CDs. There are various historic reasons for this, not the least of which has been "loudness wars" in the music business. But historically, most CDs were normalized for a peak level somewhere slightly below 0 dBFS. This was typically after a fair amount of dynamic processing (limiting/compression) to reduce the dynamic range, particularly on "pop" music.
The end result of this is that if you actually take some commercial CDs and ingest the audio to an editor with an accurate loudness meter, you'll typically see loudness of -12 to -18 LKFS. This is some 6 to 12 dB louder than the levels recommended by SMPTE and now the loudness specs for professional television broadcast.
So why wouldn't you want to use -23 for your library. If you put the files with the -23 audio on your smart phone, you probably won't be able to turn the headphones up enough to properly listen to the music, particularly in Europe, which has limits on headphone loudness to protect hearing. The gain, and the limits in smartphones were based on the louder files, recorded at -12 LKFS or so.
The other issue is when playing the files on a device with more than one source like a receiver with a tuner or a car radio. You might well be able to turn the gain up enough to hear the -23 tracks at a reasonable level, but if you then switch the input to, let us say the tuner, you are going to be blasted with really loud audio from the tuner. This is because the circuit designers designed the gain structure for the levels to come close to matching with audio sources like commercial CDs or downloads, which are usually in that -12 to -18 LKFS range.
Finally, there has been some considerable discussion and research in the commercial recording business about using the loudness measurements for CD and download releases, but they all revolve around suggested levels of -14 to -18 LKFS. There have been several suggestions to standardize on -16. -18 as used now by dBpoweramp is a nice conservative choice which will play nicely with most consumer equipment with a little more headroom than you find in most pop recordings.
FYI, I am retired from a 36 year career as an audio/video systems engineer with one of the major USA commercial broadcast networks, and was responsible for overseeing the installation of loudness monitoring and control equipment there when the FCC passed a rulemaking enforcing loudness limits on television broadcasting. I also do quite a bit of live music location recording and use loudness software in processing my recordings.
It would be worthwhile for people to search old threads on this subject. As I have posted here before, the choice of -23LuFS/LKFS or thereabouts in the various loudness standards was based on the levels used in professional television broadcast applications (for which the standard was written and intended). Professional broadcast audio levels in the plant are very much lower than the levels that have typically been used for digital consumer products like CDs. There are various historic reasons for this, not the least of which has been "loudness wars" in the music business. But historically, most CDs were normalized for a peak level somewhere slightly below 0 dBFS. This was typically after a fair amount of dynamic processing (limiting/compression) to reduce the dynamic range, particularly on "pop" music.
The end result of this is that if you actually take some commercial CDs and ingest the audio to an editor with an accurate loudness meter, you'll typically see loudness of -12 to -18 LKFS. This is some 6 to 12 dB louder than the levels recommended by SMPTE and now the loudness specs for professional television broadcast.
So why wouldn't you want to use -23 for your library. If you put the files with the -23 audio on your smart phone, you probably won't be able to turn the headphones up enough to properly listen to the music, particularly in Europe, which has limits on headphone loudness to protect hearing. The gain, and the limits in smartphones were based on the louder files, recorded at -12 LKFS or so.
The other issue is when playing the files on a device with more than one source like a receiver with a tuner or a car radio. You might well be able to turn the gain up enough to hear the -23 tracks at a reasonable level, but if you then switch the input to, let us say the tuner, you are going to be blasted with really loud audio from the tuner. This is because the circuit designers designed the gain structure for the levels to come close to matching with audio sources like commercial CDs or downloads, which are usually in that -12 to -18 LKFS range.
Finally, there has been some considerable discussion and research in the commercial recording business about using the loudness measurements for CD and download releases, but they all revolve around suggested levels of -14 to -18 LKFS. There have been several suggestions to standardize on -16. -18 as used now by dBpoweramp is a nice conservative choice which will play nicely with most consumer equipment with a little more headroom than you find in most pop recordings.
FYI, I am retired from a 36 year career as an audio/video systems engineer with one of the major USA commercial broadcast networks, and was responsible for overseeing the installation of loudness monitoring and control equipment there when the FCC passed a rulemaking enforcing loudness limits on television broadcasting. I also do quite a bit of live music location recording and use loudness software in processing my recordings.
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