DIY modifications for acoustically transparent headphones

Acoustically transparent headphones are an important tool for Augmented Reality (AR) research. To supplement a real acoustic scene with virtual sound sources or virtual acoustics, previous studies have used the very open AKG K1000. Since this model was discontinued and is expensive on the second-hand market, we present modifications to a regular open headphone. Measurements show that cutting out pieces of the ear-pads can yield transparency characteristics comparable to the K1000. Fully surrounding transparency measurements of the original and the modified models are presented. Moreover, based on headphone transfer function measurements, minimum-phase filters are derived, to compensate for the loss of low frequencies after modification. The instructions and open measurement data make it easy to replicate this DIY solution.