Tatsuya Hirahara and Kazuo Ueda
Investigation of headphones suitable
for psychophysical experiments
Abstract:In order to find the appropriate headphone for the
psychophysical experiments, the frequency response of twelve
headphones were measured by three physical methods; on an IEC
coupler (B&K 4134), on a C coupler attached to a head and torso
simulator (Kohken SAMRAI) [K.Okabe et al. J. Acoust. Soc. Jpn. (E) vol.5
pp.95-104] and by using a probe microphone in actual ears. The
results showed a very few electro-static circumaural headphones (e.g.
STAX SR-Lambda Pro.), have relatively flat frequency characteristics
with excellent invariance among the measuring methods. In contrast,
many dynamic supra-aural headphones (e.g. Rion AD02, Beyer DT48,
Elegacous DR831, etc.), have poor frequency characteristics, especially
at lower frequencies, and differ a lot among the three measuring
methods. For these headphones, the energy leakage at lower
frequency region is inevitable, since the headphone pad fitting to the
pinna is usually incomplete, and acoustic impedance of the diaphragm
is very high. These undesirable characteristics might affect the
psychophysical experiments. As one example, results were severely
affected by headphone differences in the vowel identification test
using several synthesized vowels of which F0 component amplitude
were manipulated. The physically-determined frequency responses
were contrasted with those from a psychophysical loudness matching
procedure [K.Ueda, et al., J.Acoust.Soc.Am.87, Suppl.1].