B Relation between sound intensity and frequency

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1. May 22, 2017

Tulio Cesar

The sound intensity formula is given by: dE/dT*dS. So the variables are energy, related to the amplitude of the wave, area, related to wavefronts distribution on space, and time. So many times I don't see any reference about the relation between frequency and sound intensity, but if time is a variable, so shouldn't it be important to know how much time the energy of a wave does take to pass through an area? If so, is it correct to assert that the G note, having the same amplitude (and consequently being as loud) of A note, has therefore more sound intensity?
Please correct any conceptual mistake i may have done and elucidate the topic for me.

2. May 22, 2017

nasu

It depends on ow do you define the amplitude. If you describe the wave by particle displacement then indeed the intensity depends on frequency.
However, more common is to use pressure amplitude and in this case the intensity does not depend on frequency.

If you are talking about hearing a sound, then the sensitivity of the ear depends on frequency and sounds with the same intensity but different frequencies may be perceived as having different loudness levels.