Headphones

Matching the measured frequency response of a headphone via an artificial ear with the subjective experience of listeners remains a rich source of debate, particularly in respect of bass and presence. Some (uncorrected) responses published online fail to account for the 'real world' impact of the swirls of the ear's pinna and ear canal – and correlation with listening tests is typically poor.

Our headphone reviews usually include three weighted traces, starting with a simple free-field target response that emulates the perceived soundfield from a pair of stereo speakers. Then there's the standard diffuse-field response that targets a soundfield with no particular point source, an option 'tweaked' by researchers at Harman who are promoting an additional boost below ~200Hz.

However they are weighted, our own headphone tests continue to show big variations between the responses of many models. More specifically, a brief trawl of the forums suggests many listeners prefer a cranked up bass, perhaps compensating for the poor head/ear seal of their chosen capsules. Perhaps this is why iFi Audio, with its own ear tuned to the headphone community, continues to offer its 'XBass' EQ adjustment to 'rebalance bass-light 'phones'. This delivers a bass uplift below 100Hz, reaching a substantial +9dB/20Hz and +11dB at subsonic frequencies [red trace, inset Graph]. With no subtle trim offered here, this 'binary' bass boost should be applied with caution. PM