The thing is that the amount of bass that is “correct” is not objectively determined or determinable - different people have different preferences on how much bass is “correct”.
This includes music producers and musicians (people who know exactly how much bass they want).
That’s why the amount of bass in a headphone should be dialled in by the user according to their own preferences.
We know from research (S.Olive et al, 2018) that there are roughly 3 groups of people:
- group 1 (2 out of 3 people, ~65%) prefer a bass boost of around 5 dB. That’s the amount of bass specified in the Harman Target. 2 out of 3 people will agree that this is the correct amount of bass (give or take 1-2 dB)
- group 2 (1 out of 5 people, ~20%) prefer less bass than that, somewhere between 0 and 3 dB of bass boost. That’s the amount of bass specified in the “Optimum HiFi Target”. 1 out of 5 people will agree that this is the correct amount of bass.
- group 3 (1 out of 7 people, ~15%) prefer much more bass than that, somewhere between 10 and 15 dB of bass boost. 1 out of 7 people will agree that this is the correct amount of bass.