4,495 research outputs found
Optimal source distribution for binaural synthesis over loudspeakers
No full textWhen binaural sound signals are presented with loudspeakers, the system inversion involved gives rise to a number of problems such as a loss of dynamic range and a lack of robustness to small errors and room reflections. The amplification required by the system inversion results in loss of dynamic range. The control performance of such a system deteriorates severely due to small errors resulting from, e.g., misalignment of the system and individual differences in the head related transfer functions at certain frequencies. The required large sound radiation results in severe reflection which also reduces the control performance. A method of overcoming these fundamental problems is proposed in this paper. A conceptual monopole transducer is introduced whose position varies continuously as frequency varies. This gives a minimum processing requirement of the binaural signals for the control to be achieved and all the above problems either disappear or are minimized. The inverse filters have flat amplitude response and the reproduced sound is not colored even outside the relatively large "sweet area." A number of practical solutions are suggested for the realization of such optimally distributed transducers. One of them is a discretization that enables the use of conventional transducer units
Systems for virtual acoustic imaging using the binaural principle
No full textAvailable from British Library Document Supply Centre- DSC:DN057050 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
Off-axis cross-talk cancellation evaluation of 2-channel and 3-channel OPSODIS soundbars
No full textOptimal Source Distribution (OPSODIS) theory enables binaural cross-talk cancellation (CTC) without significant losses in dynamic range and audio quality, associated with alternative forms of transaural systems. Two types of sound-bars, a 2-channel OPSODIS and a 3-channel OPSODIS, have been developed and have proven to offer good binaural reproduction for a central, on-axis listener. This paper aims to evaluate their ability to offer CTC for second and third listeners inoff-axis positions, within a realistic home listening environment
Low-complexity, listener’s position-adaptive binaural reproduction over a loudspeaker array
No full textThis work presents a method for binaural reproduction over a loudspeaker array that adapts to the listener’s position by using a cross-talk cancellation approach that is updated in real-time. This is obtained by combining the audio signal processing system together with a computer vision mechanism that estimates listener’s position. A novel approach to adapt the cross-talk cancellation filters is introduced here, which employs filters created for a central listening position using a free-field propagation model and far field beamforming techniques, hencerequiring little memory and processing. The paper introduces simulations to show the effectiveness and robustness of the formulation together with free-field measurements of performance using a 16 loudspeaker compact array
Creation of virtual sound environments using geometrical acoustics and finite elements method
No full textIn this paper, the sound pressure field of a small room was analysed using geometrical acoustics methods, a wave equation method in the frequency domain and binaural impulse response measurements in order to create virtual sound environments for specific source-receiver positions. The GA methods were applied using CATT-Acoustic, where the Randomised Tail-corrected Cone-tracing was implemented in order to generate binaural impulse responses. The wave equation technique was applied using ACTRAN, which utilizes FEM to estimate the sound pressure field. Afterward, a hybrid method combining GA and FEM was implemented via Off-line signal processing to create binaural impulse responses using the frequency ranges where each technique provides more reliable results. Finally, the realised virtual sound environments were verified against the binaural impulse response measurements by means of objective and subjective methods
A listener adaptive optimal source distribution system for virtual sound imaging
No full textThis paper describes the use of an optimal source distribution loudspeaker array for binaural reproduction. In this paper, the device is made adaptive to the listener’s position. This is obtained by using a fixed set of crosstalk cancellation filters created for a central listening position plus a listener-position dependent delay network, which varies the delay of each loudspeaker unit to maximise the cross-talk cancellation response at the listener’s position. The paper introduces the formulation required for the adaptive control and simulated results predicting the performance of the device for symmetrical and asymmetrical listening positions. It is also shown how the proposed formulation has been implemented on a Sherwood S7 OPSODIS soundbar
Binaural reproduction capability for multiple off-axis listeners based on the optimal source distribution principle
No full textThis paper presents a theoretical, analytical and experimental studies for synthesizing virtual auditory space to multiple listeners using binaural synthesis over two-channel loudspeakers. The optimal source distribution (OPSODIS) improves many of the problems arising with the binaural reproduction over loudspeakers. The principle utilizes the idea of a pair of conceptual monopole transducers whose azimuthal location varies continuously as a function of frequency. In this paper, theoretical considerations under free-field conditions and numerical calculations including the effect of head related transfer functions for off-axis listeners are presented. It is revealed that the OPSODIS can also provide the same binaural signals as for the on-axis target listener to the ears of multiple off-axis listeners.</p
Investigating multiple off-axis listening positions of an OPSODIS sound bar
No full textOPSODIS Ltd released a sound bar capable of reproducing binaural signals at a listeners' ear and create a surround sound environment for a small number of listeners' seated in front. The Optimal Source Distribution theory allows for the near perfect reproduction of binaural signals at a listeners ear with crosstalk suppression at the other ear without the drastic reduction in dynamic range and audio quality as seen with other methods of transaural playback.This removes the need to mount speakers around a listening space in order to achieve surround sound thus providing an often more elegant solution to otherwise cumbersome 5.1, 7.1 and 11.1 set ups
Letter from Takashi Matsuura to Mrs. and Mrs. S. Okine, October 19, 1948 [in Japanese]
No full textA letter from Takashi Edwin Matsuura to his uncle, Seiichi Okine. Takashi thanks Seiichi for his hospitality during his visit to the the Okines' place as well as the gift of the flowers. He informs that he arrived home safely at 9:00 PM on Monday and that Mr. Freitas was pleased to hear about Takashi's visit to the Okines. He also writes about an upcoming New Years performance in Los Angeles, and informs that his children, Shizuka and George will visit the Okines when Jokichi Yamanaka returns to the U.S. The arrival of the letter, October 22, 1948, and the reply date, [October] 25, are recorded on the backside of the envelope.The Okine Collection contains materials collected by Seiichi and Tomeyo Okine who were Issei flower growers in Whittier, California. It includes correspondence, photographs, financial documents, and a photo album. A large portion of the collection consists of family correspondence with Seiichi and Tomeyo Okine, including letters from their Nisei children, Masao and Makoto Okine, both soldiers overseas during World War II, to their Issei parents incarcerated in the Rohwer incarceration camp in McGehee, Arkansas. The correspondence also includes letters from their relatives and friends who are former incarcerees in the camps during the war and have “resettled” in Chicago, Illinois as well as letters from the Okines’ family members in Hiroshima, Japan during the Allied occupation of Japan. In addition, the collection includes a family photo album compiled by Dorothy Ai Aoki, a Nisei daughter to the Okines
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