Sunday Sound Thought 10 – Spectral Loudness
As the year continues, many of these posts will be philosophical in nature. Some will be in contradiction to previous postings. These are not intended as truths or assertions, they’re merely thoughts…ideas. Think of this as stream of consciousness over a wide span…though this week’s is a physiological than philosophical
This week’s thought isn’t anything new. In fact, it’s something that gets brought up randomly throughout the community. It’s recurrent for a good reason though…it’s the idea that you can make something seem louder by expanding the spectral content without actually increasing the volume. A wider spectral pattern activates more of the inner ear’s “critical bands.” The more bands that are activated, the louder something seems…even if the dB-SPL measurement stays the same.
Then there’s the distortion/clipping side of the coin. It makes use of this very effect to increase the perceived loudness. Distortion adds harmonics, increasing the activation of critical bands in the inner ear, but remember that it does this by changing the waveform…giving it more time in the “crest/trough zone” per cycle. It changes the RMS measurement. Depending on how it changes the wave form crest/trough, it can also increase the empirical, not just the perceived, loudness level.
Thanks for indulging me while I reminded myself of this…awareness of the spectrum is important in sound design.