It's tempting to look at the prices for some of these Head And Torso Simulators (HATS) and ear-simulators thinking that one needs this level of equipment in order to test headphones. Also, it seems that some manufacturers can change headphone characteristics even within the same product line - for example, check out the variability with the Campfire Andromeda IEM. The variability among humans and measurement techniques are also well laid out in this 2008 Stereophile article by Keith Howard.īy the way, do not forget the variability between the same model of headphones as well! Quality controls will affect the variability between each headphone made. Unlike speakers where we can generally agree on measurements based on how a speaker would perform anechoically, headphone performance by definition is affected by the interface or "coupling" between it and whatever measurement system it's being applied to, whether just a flat plate, some kind of simulated "ear" system, or even live human subjects in some instances (I believe Rtings does this, check out their "Challenges & Solutions" video). It's interesting when we look around at headphone measurements online and notice just how variable the frequency response graphs presented are among sites like In-Ear Fidelity/Crinacle, InnerFidelity, DIY-Audio-Heaven, Rtings, Reference Audio Analyzer, and Audio Science Review. Nonetheless, I do believe the inexpensive US$199 price has indeed brought "headphone measurement capability to the masses" and opened up the opportunity for the hobbyist audiophile to explore relative sound quality of headphones without aiming for absolute "industry standard" results. I can certainly understand Brent Butterworth's concerns and article about the miniDSP EARS back in 2018. Regardless, a compensation curve will need to be applied to correct for the resonances (miniDSP includes their IEM Diffuse-Field "IDF" compensation which we'll look at another time). Be careful with IEMs, especially those with longer tips that could jam against the microphone. Human external auditory canals are more complicated than this which would affect the resonance characteristics leading to the tympanic membrane.
Getting good, consistent on-ear headphone measurements has been by far the most difficult task I've tried thus far (hint: use some large, thick rubber bands around supraaural headphones to clamp down on the pinnae helps).Īnother area of concern is that the ear canal is just a straight tube leading to the measurement microphone inside. The higher density and lower compliance of the pinnae will also make it a bit more difficult to measure on-ear (supraaural) headphones with a proper seal however, leading to inaccurate poor bass response. Generally, with a bit of care, I have not found this to be a big problem. I know some folks have removed the screws and I've also had some success with using thin foam tape (like the soft skin-hugging tape used in Band-Aids) to smooth out the irregularities as well. If you have one of these, be mindful of the 4 screws holding down the synthetic ear/head in place these areas of depression can make it more difficult to create a good seal.