In order to develop headphone calibration profiles, we at Sonarworks have measured over 7000 headphone units spanning 900 different headphone models using the same in-house developed methodology. Our preliminary internal listening tests concluded that while few headphone models sound nearly identical to all test participants, for most models each listener perceives the frequency response differently. In order to find the accuracy limits of our headphone calibration, we specifically trained an expert critical listening panel of 5 people, who by using an equalizer are able to fine-tune the calibration curves to match the perceived frequency response of headphones to a neutral reference: SoundID calibrated near-field studio stereo speakers, placed in an acoustically treated sound studio.
The graph above shows trained listener perceived frequency response deviation for Sonarworks flat frequency response calibrated headphones with a 90% confidence interval. Sonarworks calibration, as validated by the trained human listener panel of 5 people, is +/-3dB in the 200Hz to 2.5kHz range (dark blue) and +/-6 dB in the full audible frequency range (light blue). The increased deviation at low frequencies is due to individual headphone to ear and head fit and high frequencies are more affected by individual ear-specific acoustic properties. This deviation is an inherent characteristic of headphones that stems from the fact that the perceived headphone frequency response is dependent on the listener.
Continue reading about our other findings in our blog’s Research section.