Wayne Parham Messages: 18755 Registered: January 2001
Illuminati (33rd Degree)
If you think about it, the various equal-loudness curves are sort of like filters. I mean, they're not a filter applied to a signal like the RIAA curve used on vinyl albums. But they are a representation of SPL/Frequency - a plot that represents how loud a frequency is perceived compared to other signals of other frequencies, given a specified amplitude.