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Topic: TT Dynamic Range Meter RMS question (Read 3850 times) previous topic - next topic
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TT Dynamic Range Meter RMS question

There are some websites posting RMS values of different albums to explain the loudness war issue, sometimes TT DR Meter is used.

Here is the question. I found that RMS value from TT DR meter is different from what I see in Adobe Audition. By default, Audition uses the parameter "0dB=FS square wave" and "50ms window width" and the help file says "average RMS power" is the value used to estimate perceived loudness. However TT DR meter's RMS value is very similar to Audition's "0dB=FS sine wave" and "total RMS power"

For example, when analyzing the same file, TT DR meter shows...
Left -15.1/Right -13.9

Audition shows...
Left -18.53/Right -17.59 ("0dB=FS square wave" and "average RMS power")
Left -15.12/Right -13.89 ("0dB=FS sine wave" and "total RMS power")

Which one is more correct when talking about perceived loudness? What is your opinion?

TT Dynamic Range Meter RMS question

Reply #1 –
Neither one is more correct...  It's just a different 0dB reference.  When you compare two songs, just use the same method on both songs.

A 0dB full-scale square wave has a higher average or RMS value than a 0dB full-scale sine wave...  The sine wave only touches + and - peak once per cycle.  A square wave is always hitting either the + or - peak.

The square wave has a higher RMS value, so if you use the square wave as your 0dB reference, your file will calculate to a lower level (compared to an RMS reference).   

If you use RMS as a reference and your sound file is square waves, your file can have an RMS value greater than 0dB.  (This will never happen with a music file...  Only with constant test-tone.)

The standard power-line voltage in the U.S. is 120VAC RMS, and the positive & negative peaks hit  about 170 Volts.    If you connect a light bulb to 120 Volts DC, it will have the same brightness (same power consumption in watts) as 120VAC.

If you connect the light bulb to a square wave with 170V peaks, it will glow brighter...  There is always +170V or -170V and it will glow at the same brightness as 170VDC.

TT Dynamic Range Meter RMS question

Reply #2 –
Thank you!