著者

César D. Salvador Shuichi Sakamoto Jorge Treviño Yôiti Suzuki

出版者

ACOUSTICAL SOCIETY OF JAPAN

雑誌

Acoustical Science and Technology (ISSN:13463969)

巻号頁・発行日

vol.38, no.1, pp.1-13, 2017-01-01 (Released:2017-01-01)

参考文献数

26

被引用文献数

3 5

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This paper derives a continuous-space model to describe variations in magnitude of complex head-related transfer functions (HRTFs) along angles and radial distances throughout the horizontal plane. The radial part of this model defines a set of horizontal-plane distance-varying filters (HP-DVFs) that are used to synthesize the HRTFs for arbitrary sound source positions on the horizontal plane from initial HRTFs obtained for positions on a circular boundary at a single distance from the head of a listener. The HP-DVFs are formulated in terms of horizontal-plane solutions to the three-dimensional acoustic wave equation, which are derived by assuming invariance along elevation angles in spherical coordinates. This prevents the free-field inaccurate distance decay observed when assuming invariance along height in cylindrical coordinates. Furthermore, discontinuities along the axis connecting the ears are also overcome, which appear when assuming invariance along the polar angle in interaural coordinates. This paper also presents a magnitude-dependent band-limiting threshold (MBT) for restricting the action of filters to a limited angular bandwidth, which is necessary in practice to enable discrete-space models that consider a finite number of sources distributed on the initial circle. Numerical experiments using a model of a human head show that the overall synthesis accuracy achieved with the proposed MBT outperforms the one achieved with the existing frequency-dependent threshold, especially at low frequencies and close distances to the head.

著者

Yôiti Suzuki Hisashi Takeshima Kenji Kurakata

出版者

ACOUSTICAL SOCIETY OF JAPAN

雑誌

Acoustical Science and Technology (ISSN:13463969)

巻号頁・発行日

pp.e23.66, (Released:2023-10-25)

参考文献数

14

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As significant errors were reported in 1985 for the international standard related to equal-loudness-level contours (ELLCs) for pure tones, the earlier international standard was fully revised in 2003 as ISO 226:2003, after 18 years of revision work. Twenty years later, the standard has been revised again as ISO 226:2023. One motivation for the revision was to reflect the lowering of the threshold of hearing at 20 Hz by 0.4 dB in ISO 389-7:2019. In addition, the following two points of substance were revised: (1) implementation of the power exponent relating loudness perception to physical intensity formulated in an academic paper published in 2004, which describes the derivation of ELLCs relating to ISO 226:2003, and (2) adoption of mathematical expressions that preserve the appropriate number of significant digits. In this review, the process of the revision and the technical details of the changes are described. The differences from the 2003 edition are only 0.6 dB at most, and the 2023 standard can be regarded as the same as the 2003 edition in terms of practical use.

著者

Kenji OZAWA Yoshihiro CHUJO Yôiti SUZUKI Toshio SONE

出版者

Japan Society of Kansei Engineering

雑誌

KANSEI Engineering International (ISSN:13451928)

巻号頁・発行日

vol.3, no.4, pp.25-30, 2002 (Released:2010-06-28)

参考文献数

8

被引用文献数

7 11

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A psychoacoustical experiment was conducted to examine the basic characteristics of auditory presence as the first step to obtain a full understanding of the multi-modal sensation of presence. Twenty-three sounds were binaurally recorded using a dummy head and reproduced to four subjects by headphones. The experiment was carried out using Scheffé's paired comparison method modified by Ura using a scale of five categories. Analysis of variance revealed that the auditory presence as the main effect was highly significant. As a result of scaling, the sounds of moving sound sources were evaluated as having a higher presence than the sounds of stationary sound sources. As for the latter, sounds with larger sound images were rated as having a relatively higher presence. The effects other than the main effect and the interactions between them, however, were also significant. In the interactions, the individual differences for the main effect tended to be explained as the difference in weights of the subjects on the psychological factors involved in the auditory presence.