When they mapped our these curves also known as 'Equal Loudness Contours' they looked something like this: When you look at these curves, you'll notice that when the kHz range is at 0dB or just barely audiblefrequencies at 20Hz about as low as you can perceive a distinct tone have to be raised over 60 dB which is 64 times as loud.
Likewise, you might turn down the upper mids and highs because they sound louder in comparison. The effect they describe has a big impact on your approach to mixing music. Don't drive yourself nuts though.
So you so turn it up.
Munson published their seminal paper in the Journal of the Acoustic Society of America entitled "Loudness, its definition, measurement and calculation. When listening to music through your studio monitors or headphones … As the actual loudness changes, the perceived loudness our brains hear will change at a different rate, depending on the frequency.
Equal loudness curves in mastering All this psychoacoustic research into quantifying loudness has a big impact on your masters. Among his achievements: the invention of the 2-A audiometer creating one of the earliest hearing aids contributing to experiments that earned a Nobel Prize for Physics membership in countless scientific societies and the accolade of being known as the father of stereophonic sound.
Your goal is to minimize the difference as much as possible by achieving a pleasing mix at all volumes. After a sound wave enters your ear canal, your eardrum transmits the vibrations to the fluid in your inner ear with small bones called ossicles. But every time you turn it up it gets slightly harsher and more irritating to listen to.
It also causes music producers to consider how they want to attract people to their music, and keep them interested in it.
If you try to compensate first, then there will be double compensation and too much bass!