Unlike microphones, our sensitivity to sound is different at different frequencies. Experiments have shown that we are most sensitive in the midrange (2-5 kHz) and less sensitive in the very low and very high frequencies. Thus, we can still fall asleep even with the noise of our heart pumping blood through our arteries. To make matters more complicated, the sensitivity of the ear depends not only on frequency, but also on the overall sound level. At very high sound levels, the ear response is much flatter and we are almost equally sensitive to low and high frequencies.
Audyssey
Dynamic EQ is an example of an algorithm that was developed to address these differences in loudness perception. Movie and music content is mixed at very high levels in the studio where mixers and artists make their decisions about how everything should sound. But, at home we turn the volume down and this changes our perception of the sound. Bass starts to disappear and, if we are listening to a movie, the surround sound starts to diminish. These need to be adjusted so we can appreciate it at lower volumes, not just when we are cranking it.
