Kazuo UEDA, Tatsuya HIRAHARA
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.