Frequency response of headphones measured in free field and diffuse field by loudness comparison

Abstract

Loudness comparisons were performed by four subjects, under two experimental conditions: free field (anechoic room) and diffuse field (reverberation room). Each subject adjusted the headphone level of critical band noise bursts until they were equally loud as those from a reference loudspeaker (70 dB SPL). Measurement scatter was smaller in the diffuse field than in the free field. To examine the reliability of loudness judgments at high frequencies, another method—hearing thresholds by Békésy tracking—was employed. Each subject's threshold was measured with both loudspeakers and headphones. After compensation was made for the loudspeaker and room transfer functions, headphone frequency response was extrapolated from the results. This method led to high-frequency responses similar to those from loudness comparison. A loudness comparison experiment in which the subjects continuously wore a headphone was performed. However, the method of sound pressure loss measurement should be reconsidered. © 1991, Acoustical Society of Japan. All rights reserved.