Just wondering what anyone thinks about testing headphones on a coupler, with pinna and simulated ear canal, versus no pinna and no canal. The second option would just be a simple plate with a mic or mics flush mounted in it.
The pro-pinna argument might be stated: Real conditions include pinnae and ear canal. Pinnae take up some of the coupling volume, and have an effect on the response, due to reflections/resonances, particularly the concha resonance. They also have an effect on leakage (though this is highly variable for some headphones, even on real heads). The ear canal impedance can interact with the source impedance of the headphones, much like the effect of a high output impedance amplifier (tube for example), and speakers with different input impedances. This effect, called Pressure Division Ratio for headphones, is significant for some types of headphones.
The anti-pinna argument goes something like: the pinnae you will use are "average" pinnae, so not correct for any one person. Measuring through the ear canal adds a resonance in the measurement which "obscures" it. The pinna and ear canal resonance are not "heard" by people, i.e. the brain takes it into account already, since we always listen through it. So no need to measure it.
My argument is that the pinna measurement is more accurate. Using "average" pinnae introduces some error, but using NO pinnae introduces more. Including the ear canal resonance and pinna response in the measurement is not a problem. If we want to make the measurement look visually flatter for a neutral measurement, we can use a standardized inverse ear canal filter to flatten the plotted curves, while still measuring at the ear drum (DRM reference point).
Thoughts? Fire away...