AES 東京コンベンション 2009
Poster Session P3

P3 — 三次元音響と再生

Saturday, July 25, 12:00 — 16:00 (Core Time for Odd Numbers: 14:00-15:00, Core Time for Even Numbers: 15:00-16:00)
座長: 岩谷 幸雄 (東北大学)

P3 - 1   仮想環境のためのマルチチャネル音響合成法に関する検討

A method on multi-channel sound synthesis is proposed for creating virtual acoustic environment in computer graphics productions. Impulse responses with spatial information are generated from virtual sound source distribution. For desired reproduction channel setups, total impulse response is decomposed into channel components, and each response is convolved with source signal. The method is easily adaptable when location and direction of observation point in virtual graphical scene switches frequently.

P3 - 2   反響を含んだHRTFによる3D音響システム構築

佐治 晃, 丹野 慶太, 李 華康, 香村 和裕, 勝俣 達哉, 黄 捷 (公立大学法人会津大学)
In this paper, we proposed a new method using HRTFs that contain room reverberations(R-HRTF). The reverberation is not added to the dry sound source separated with HRTF but contained at their measured process in the HRTFs. We measured the HRTFs in a real reverberant environment for directions of azimuth 45, 90, 135 (left side) and elevation from 0 to 90 (step of 10 degrees) degrees then constructed a 3D sound system with the measured R-HRTF with headphones, examine if the sound reality is improved. As a result, we succeed to create 3D spatial sound system with more reality compared with traditional HRTFs sound system.

P3 - 3   3次元立体音響生成の為のバイノーラル反響の再構築

丹野慶太 , 佐治晃 , 李華康 , 勝俣達哉 , 斎藤伸彦 , 黄捷 (会津大学)
Artificial reverberation is often used to increase reality and prevent the in-the-head localization in a headphone based 3-D sound system. In traditional method, monaural reverberations were used. In this research, we measured impulse responses of an ordinary room by Four Point Microphone method, and calculated the sound intensity vectors by the Sound Intensity method. From the sound intensity vectors, we obtained the image sound sources. A binaural reverberation was reconstructed by the estimated image sound sources. Comparison experiments were conducted for 3 kinds of reverberations, i.e., monaural reverberation, binaural reverberation and binaural reverberation added with Head-Related Transfer Function. From the results, we could clarify the 3-D sounds reconstructed by binaural reverberation with head-related transfer function has the best spatiality.

P3 - 4   低周波数帯域における両耳間相関係数の弁別調査とダミーヘッドマイクを用いた実音場計測インパルス応答による検証

We investigated the discrimination of sounds that have interaural correlation coefficient (ICC) of low frequency sound below around 100 Hz by using 1/4 octave band noise in dichotic listening. We also measured ICCs at low frequencies in several rooms with different volumes. The ICCs were obtained from an impulse response recorded by a head and torso simulator. At reference ICC 1.0 the lower threshold is 0.98; at 0.9 it is 0.85, and the upper threshold is 0.96; and at 0.8 the lower one is 0.68, and the upper is 0.88. The equivalent subjective diffuseness for the 1/4 octave band noise with the center frequency of 106 Hz and ICC of 0.9, are obtained by ICC of 0.71 at 250 Hz and ICC of 0.34 at 500 Hz. The measured ICC in a small room with a volume of less than 100 m3 is almost 1, and the ICC in large room with a volume of more than 1700 m3 is about 0.8.

P3 - 5   耳の逆側における簡略化されたHRTFを用いた音像定位能力の主観評価

渡邉貫治 (秋田県立大学システム科学技術学部), 小玉亮介 (秋田県立大学大学院システム科学技術研究科), 佐藤宗純 (秋田県立大学システム科学技術学部), 高根昭一 (秋田県立大学システム科学技術学部), 安倍幸治 (秋田県立大学システム科学技術学部)
Simplification of head-related transfer functions (HRTFs) is important for effective implementation of their synthesis from computational point of view. It can be found from the frequency resolution of the auditory system that the detailed spectral form of the HRTFs is not evaluated at high frequency region. This may enable the simplification of the HRTFs to some extent. In this paper, the HRTF on the contralateral side was flattened in the higher frequency region than a certain frequency so as to retain the interaural level difference and interaural time difference. To evaluate the influence of simplified HRTFs, a localization test was carried out. The experimental results showed that HRTFs on the contralateral side could be simplified above 4 kHz.

P3 - 6   後方音源の頭部伝達関数における低域の周波数特性上の谷の空間分布

大谷 真, 岩谷 幸雄, 曲谷地 哲, 鈴木 陽一 (東北大学電気通信研究所)
Previously it was reported that the lowest-frequency spectral notch (first notch) on head-related transfer function (HRTF) play a role in sound image localization; high-frequency spectral notches (called N1 and N2) are important for sound image localization in elevation. However, another spectral notch (labeled N0) at relatively lower frequency appear in the same frequency range for sound sources behind a listener. In this study, we examined the spatial distribution of such low-frequency notches based on several subjects' measured HRTFs, and subsequently investigated whether such spectral notches can contribute to sound localization. The results showed that, in some cases, N0 exists at lower frequency than N1, indicating that a N0 provides localization cues for sound sources behind a listener.

P3 - 7   卵型スピーカシステム

茶谷 郁夫(ビフレステック株式会社)、中島 平太郎(ビフレステック株式会社)
This is a report on our challenge and achievement of creating unique performance specifications and sound quality through adoption of smooth curved surface for overall dynamic speaker system design. Enclosure is shaped like an egg and speaker diaphragm is curved to match the overall enclosure form. In order to achieve smooth and even sound radiation without any disturbance, speaker edge surround and frame are not visible from outside and there is no speaker grill. As a result, we were able to develop a speaker system with very high S/N ratio across wide frequency range, allowing reproduction of subtle nuances, and with ability to create superb sound stage. Furthermore, a large number of favorable attributes, in addition to wide dispersion and smooth sound radiation, could be observed.

P3 - 8   スーパーハイビジョン・22.2マルチチャンネル音響システムにおけるコンテンツ制作手法

山口朗史((株)NHKメディアテクノロジー), 緒形慎一郎(NHK), 下村浩一 (NHK).
The 22.2 multichannel sound system is a high-presence sound format that is superior to the 5.1 surround sound system, and NHK intends it to be the format for the next generation of TV broadcasting. NHK started to make Super Hi-Vision (SHV) content for experiments and exhibitions in 2002 and exhibited the 22.2 multichannel sound system as part of the SHV system for the first time at the Aichi World Expo in 2005. This system has also been demonstrated at the National Association of Broadcasters (NAB) convention and the International Broadcasting Convention (IBC). This paper reports on the 22.2 system's method of recording sound fields and the technique of achieving ``3D stereophony'' in post-production for the program "Gift" that was exhibited at NAB2009.

P3 - 9   22.2マルチチャンネルサラウンドによる大型音楽番組「紅白歌合戦」 の3次元立体音響のためのサウンドデザイン及びリアルタイムミキシング手法

下村 浩一(NHK)、緒形 慎一郎(NHK)、北島 正司(NHK)、山口 朗史(NHK-MT)
The public viewing of ``Kouhaku Uta Gassenn'', one of the most famous music programs in Japan, was held at NHK Fureai Hall in Tokyo on December 31, 2008. The program was mixed live using the 22.2 multichannel system, which is highly expected to be a potential audio format for future TV broadcasting audio format. This paper introduces an overview of this public viewing, including the 22.2 multichannel sound system flow and live three-dimensional sound mixing technique.

Last modified: Mon Jun 22 20:48:00 2009