中山 雅人

・本発表では、頭部伝達関数の前方定位強調に基づくセミトランスオーラルシステムの検討を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・本発表では、極小オーディオスポット形成における音圧改善に向けたDSB変調型分離放射法の検討を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・本発表では、フレキシブルパラメトリックスピーカによるオーディオスポット形成の評価を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・本発表では、観測音声の後続減衰量に基づく残響時間推定に関する検討を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・本発表では、球形パラメトリックスピーカを用いた両耳間音圧差の時間変化に基づく移動音像構築に関する検討を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・本発表では、視聴覚統合による音源数推定を利用した多人数会話の話者ダイアライゼーションの検討を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・非定常性を評価できる連の検定に基づいて、雑音環境適応型重み付き反復スペクトル減算を行う雑音抑圧手法を提案した。 ・論文執筆の全般を担当。特に理論構築を主担当

・客観的な音声品質評価指標であるPESQと室内音響指標を用いた雑音・残響指標NRSR-PAに基づく雑音・残響下音声認識性能の予測手法を提案した。 ・論文執筆の全般を担当。特に理論構築を主担当

・遠隔発話音声の線形予測残差の尖度に基づいて、近接/遠隔話者を判別する手法を提案した。 ・論文執筆の全般を担当。特に理論構築の検証を担当

Recently, technologies for reproducing a 3-D sound field are required for providing highly realistic sensations. We previously proposed a system with multiple parametric loudspeakers that have a higher directivity by using ultrasound to reproduce an audible sound in a particular area. These loudspeakers can design sound images on walls, ceilings, and floors by reflecting an emitted sound, and thus, the proposed system can easily present incoming sound from various directions. However, it is difficult to maintain the performance of sound image localization when a listener moves away from the reproduction area of the emitted sound. In this paper, we propose a sound image design method with robust localization for moving listeners. In order to constantly present the sound image localization, the method needs to steer the direction of emission in accordance with the movement of the listener. To enable this, we developed a curved-type parametric loudspeaker consisting of ultrasonic transducers arranged in an arc. The proposed method can steer the emitting direction by switching the input ultrasonic transducers without moving itself. Experimental results clearly demonstrate the effectiveness of the proposed method.

The distance estimation method based on interference of linear chirp sound has been proposed. However, the measurement performance was degraded by additional noise. In this paper, we expand the method to a method that is robust to noisy environments by introducing a concept of synchronous addition and spectral subtraction. Finally, we confirm the validity and effectiveness of the expanded method through experiments.

・リニアチャープ音の干渉に基づく音響測距法における雑音環境下での性能評価と雑音対策手法を提案した。 ・論文執筆の全般を担当。共同研究者として、特に理論構築の検証を担当

・騒音環境下におけるRahmonicとMFCCを用いた叫び声検出手法を提案した。 ・論文執筆の全般を担当。特に理論構築の検証を担当

・本発表では、直接・間接型スピーカを用いた残響再現可能な反射型オーディオスポットシステムに関して検討を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・本発表では、帯域和音付与に基づく不快騒音の快音化に向けた最適帯域幅の検討を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・本発表では、曲面型パラメトリックスピーカを用いた移動音像構築の評価を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・本発表では、キャリア波と側帯波の分離放射におけるパラボラ反射型オーディオスポット形成による音圧改善の検討を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・本発表では、反復固有値解析に基づくサブスペース型スペクトルサブトラクションの検討を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・ペアマイクロホンのクロススペクトルにおける位相干渉を利用して、対象物の位置を測定する手法を提案した。 ・論文執筆の全般を担当。共同研究者として、特に理論構築を担当

・波動方程式の有限時間差分法（WE-FDTD）を用いて、頭部近傍スピーカアレーによるセミトランスオーラル方式に基づく3次元音場再現手法を提案した。 ・論文執筆の全般を担当。特に理論構築を主担当

・パラメトリックスピーカにおける振幅変調波をキャリア波と側帯波に分離し、放射することで、ピンスポットでオーディオスポットを形成する手法を提案した。 ・論文執筆の全般を担当。特に理論構築を主担当

Desired/undesired speech discrimination is as important as speech/non-speech discrimination to achieve useful applications such as speech interfaces and teleconferencing systems. Conventional methods of voice activity detection (VAD) utilize the directional information of sound sources to distinguish desired from undesired speech. However, these methods have to utilize multiple microphones to estimate the directions of sound sources. Here, we propose a new method to discriminate desired from undesired speech with a single microphone. We assumed that the desired talkers would be close to the microphone, and the proposed method could distinguish close/distant-talking speech from observed signals based on the kurtosis of the linear prediction (LP) residual signals. The experimental results revealed that the proposed method could distinguish close-talking speech from distant-talking speech within a 10% equal error rate (EER) in ordinary reverberant environments with less processing time.

Parametric loudspeaker can form an acoustic beam with sharper directivity by using multiple small ultrasonic transducers. In recent years, acoustic beam steering methods based on delay-processing for multiple small ultrasonic transducers is proposed. However, in these methods, spatial aliasing in ultrasonic waves has not been focused. Therefore, in this paper, we investigate the relationship between the spatial aliasing of ultrasonic waves and the acoustic beam of audible sounds. In addition, we propose acoustic beam steering with parametric loudspeaker by individual delay-filtering for carrier and sideband waves.

Recently, technologies for reproducing a 3 dimensional sound field are required for providing highly realistic sensations. Therefore, we previously proposed a system with multiple parametric array loudspeakers (PAL). PALs can design sound images on walls, ceilings, and floors by using the higher directivity of ultrasound. Thus, the proposed system can easily present incoming sound from various directions. However, it is difficult to provide a realistic sensation depending on the reverberation time. In addition, the listening area of one PAL is small. In this paper, we therefore propose two approaches for overcoming these problems. First, we propose reverberation steering with indirect electrodynamic loudspeakers and PALs. We also attempt to expand the listening area of the sound image with a curved-type PAL. As a result of evaluation experiments for each proposed approach, we could confirm the effectiveness of each approach.

・3chマイクロホンアレーを用いて、空間・周波数領域多重解像度走査に基づき、実時間で近接音源位置を推定する手法を提案した。 ・論文執筆の全般を担当。特に理論構築を主担当

・マイクロホンアレーを用いた送信波と反射波の位相干渉に基づく360°の方位で周辺環境を探査できる音響イメージング手法を提案した。 ・論文執筆の全般を担当。特に理論構築を主担当

・ドーム型視聴覚融合型ディスプレイ（X-Media Galaxy）における移動音像を実現するため、反射型オーディオスポットによる音像を補間する手法を提案した。 ・論文執筆の全般を担当。特に音響側の理論構築を担当

・快適な打撃音を実現できるゴルフボールを開発するため、快適音印象の分析と打撃音と物理特性の関連を分析した。 ・データ収集、分析、執筆の全般を担当

・聴覚マスキングに基づいて、ピーク周波数をもつ室内騒音に対する不快感の低減手法を提案した。 ・論文執筆の全般を担当。特に理論構築を主担当

・本発表では、ブラインドインパルス応答推定に基づく残響下音源位置推定法における距離推定精度の評価を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・本発表では、間接動電型スピーカを用いた残響時間制御による全天周ドームにおける音像プラネタリウムの高臨場化の検討を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・本発表では、パラメトリックスピーカアレーを用いた壁面反射型オーディオスポット領域の拡大の検討を行った。評価実験の結果、提案手法の有効性を確認した。 ・論文執筆の全般を担当。特に理論構築を担当

・脳血管画像の濃淡に対するコスト関数を用いた3Dモデルによって脳血管を可視化する手法を提案した。 ・論文執筆の全般を担当。共同研究者として、特に理論構築の検証を担当

・多チャンネルのブラインドインパルス応答推定に基づき、高残響下で音源位置を推定する手法を提案した。 ・論文執筆の全般を担当。特に理論構築を主担当

・パラメトリックスピーカで再生が難しい低周波数帯域をDSBと両側波帯重み付けSSBで強調することで、パラメトリックスピーカの音質を改善する手法を提案した。 ・論文執筆の全般を担当。特に理論構築を主担当

・聴覚特性に基づいて減算係数を重み付けしつつスペクトルサブトラクションを反復する雑音抑圧におけるミュージカルノイズ低減手法を提案した。 ・論文執筆の全般を担当。特に理論構築を担当

・パラメトリックスピーカによる再生音の周波数特性に着目し、その概形を表すスペクトル包絡に基づく復調評価指標を提案した。 ・論文執筆の全般を担当。特に理論構築を主担当

We study near-field sound source localization, for which two-dimensional multiple signal classification (2D-MUSIC) has already been developed. However, this method requires a lot of elapsed time because it processes in each frequency. A localization method based on cross-power spectrum phase analysis (CSP) in the near field has also been developed. However, its localization accuracy is degraded by noise sources and reverberations. To overcome these problems, we propose a new localization method based on time delay and subspace methods. Experimental results of an evaluation experiment carried out in a conference room demonstrate that the method improves localization accuracy with less elapsed time in a diffused noise environment.

Beamforming with a microphone-array is an ideal candidate for distant-talking speech recognition. An adaptive beamformer can achieve beamforming with a small microphone-array, but it had difficulty extracting distant-moving speech and reducing moving noises, because it must rapidly train long multiple-channel adaptive filters by using observed noises with a microphone-array. However, if positions of both talkers and noises can be estimated, adaptive filters may not need to be trained in real noisy environments. Therefore, we propose a multiple-nulls-steering beamformer based on both talker and noise localization that does not require adaptive training with observed noises. Finally, we confirmed the validity and effectiveness of the proposed method through computer simulations and evaluation experiments in real noisy environments. © 2013 The Acoustical Society of Japan.

In a number of engineering fields, information on the distance to the target is very important. We previously proposed an acoustic distance measurement method based on interference between the transmitted and reflected waves, which can be used for distance measurement over a short range. The previously proposed method requires equipment such as a loudspeaker and a microphone for cancellation processing of background components due to the spectrum of the transmitted wave and the transfer function of the measurement system in real environments. Therefore, in the previously proposed method, a sound source of the transmitted wave must be known in advance. In the present paper, we propose a new acoustic distance measurement method based on phase interference obtained using the cross-spectral method with stereo microphones, which does not require the condition that a sound source of the transmitted wave is known. The conventional cross-spectral method requires a measuring remote microphone and a reference microphone to be placed near a loudspeaker, meanwhile the proposed method requires stereo microphones to be placed near a sound source. Finally, we confirmed the validity and effectiveness of the newly proposed method through computer simulations and evaluation experiments in real environments. © 2013 The Acoustical Society of Japan.

In a number of engineering fields, information on the distance to the target is very important. We previously proposed an acoustic distance measurement method based on interference between the transmitted and reflected waves, which can be used for distance measurement over a short range. In the previously proposed method, a sound source of the transmitted wave must be known in advance. In the present paper, we propose a new acoustic distance measurement method based on phase interference obtained using the cross-spectral method with adjacent microphones, which does not require the condition that a sound source of the transmitted wave is known. Finally, we confirmed the validity and effectiveness of the newly proposed method through both computer simulation and evaluation experiment in a real environment.

Since the distance to target is very important information, we have proposed an acoustic distance measurement (ADM) method using a standing wave, which is generated by interference between transmitted and reflected waves. This method is very simple in that the distance between the microphone and the target is estimated as the peak value of the range spectrum (i.e., the absolute value of the Fourier transform with respect to the power spectrum of the observed wave). However, in order to measure short distances, a transmitted wave with a wide bandwidth is required. Recently, we have theoretically developed the very-close-range ADM method based on the standing wave of audible sound using a single microphone (i.e., single-channel observations) by introducing an analytic signal instead of the power spectrum. The present paper newly describes a realization of compact system for very-close-range measurement and examines experimentally the effectiveness of the proposed system. © 2013 IEEE.

Noise reduction methods have been proposed for various large noises. However, we often perceive unpleasant feeling even if the small noise arises in quiet indoor environments. To overcome this problem, we focus on auditory masking which is phenomenon that human can't hear a target noise by composite sound. In this paper, we propose the unpleasantness reduction method based on auditory masking for indoor noise. In the proposed method, we discuss how to design the artificial sound for noise control. Furthermore, we develop an active unpleasantness reduction system based on the proposed method. As a result of evaluation experiments, we could confirm the effectiveness of the development system. © 2013 APSIPA.

Conventional near-field talker localization methods with microphone-array calculate spatial spectrum in each scanning position of discretized space and each frequency. Hence, elapsed time is increased and real-time processing is difficult. Real-time processing is important for achieving the natural interaction with the speech interfaces. To overcome this problem, we newly propose a talker localization method based on Multi-resolution Scanning in Frequency Domain (MSFD). MSFD utilizes lower spatial resolution in the lower frequency band and higher spatial resolution in the higher frequency band to reduce elapsed time. We also propose a calculation method for suitable spatial resolution at each frequency on the basis of the variances of phase differences among microphones. The results of evaluation experiment indicated that the proposed MSFD could reduce the elapsed time without degrading the localization accuracy.

The automatic speech recognition (ASR) performance is degraded in noisy and reverberant environments. Although various techniques against degradation of the ASR performance have been proposed, it is difficult to properly apply them in evaluation environments with unknown noisy and reverberant conditions. It is possible to properly apply these techniques for improving the ASR performance if we can estimate the relationship between the ASR performance and degradation factors including both noise and reverberation. In this study, we here propose new noisy and reverberant criteria which are referred as "Noisy and Reverberant Speech Recognition with the PESQ and the D-n (NRSR-PDn)". We first designed the "NRSR-PDn" using the relationships among the D value, the PESQ score, and the ASR performance. We then estimated the ASR performance with the designed criteria "NRSR-PDn" in evaluation experiments. Experimental evaluations demonstrated that our proposed criteria make the well suited for robustly estimating the ASR performance in noisy and reverberant environments.

Patients who have difficulty moving their muscles freely require support for various situations that occur in everyday life. A controllable robot arm without using muscles may make the patient's quality of life improve. By using a brain-computer interface (BCI), control of the robot arm is possible by thought alone. Therefore, we have constructed several robot arms with an ultrasonic range finder and a web camera for BCI system. By utilizing these devices, collisions between the robot arm and the user could be avoided and control could be partially automated. The distance is very important information in the system. In the present work, an acoustic distance measurement (ADM) device was used. It consists of equipment with easy acquisition and does not need an electronic circuit which is in the ultrasonic range finder. It is a new device and has a possibility of simplifying the ADM device.

Since the distance to target is very important information, we have proposed an acoustic distance measurement (ADM) method using a standing wave, which is generated by interference between transmitted and reflected waves. However, the amplitude-frequency characteristics of the measuring system between the microphone and the loudspeaker are not considered, but these characteristics cannot be ignored in a real environment. To remove the effect of the measuring system, our previous methods required a 2ch microphone or two measurements with targets and without targets. This paper describes a new ADM method considering a movement of transmitting-and-receiving system composed of 1ch microphone and loudspeaker. Finally, we examine the validity and effectiveness of our method by applying it to an actual sound field.