Takaaki ANAZAWA (Bitmedia) and Keisuke KINOSHITA (NTT Communication science laboratory) gave a lecture on overview of surround audio reproduction by using Reverberation Reduction and Control Technology.
Mr.Kinoshita gave us overview and a principle about how to separate direct sound and reverberation sound based on multi-step linear prediction algorithm, which the theory was published in November 2009 under the name 'Revtrina.'
Mr.Anazawa explained about philosophy of three-imensional audio based on separation and control of reverberation. He gave a demonsration of reproduction surround sound from original stereo and monoaural audio source. Participants experienced efficient and effective results made by the technology. Also, he refered to consider possibility for many kinds of application such as improvement for clarification of audio, room acoustic compensation, etc.
Many non-member participants were there at the meeting, and all of them seemed to be satisfied and had a great time.
Yamaha Corp. completed the construction of the new Yamaha hall in February, 2010, which is in a new Yamaha building on one of the main avenues in Ginza, Tokyo, Japan. This classical and yet modern new Yamaha Hall has 12 meters of height, 11 meters of width, 15 meters of seat depth, 6 meters of stage depth, and capacity of 333 seats.
The natural reverberation time is 1.8 seconds. However, the reverberation time can be controlled using a digital signal processing-based AFC (Active Field Control) technology of Acoustic Research Laboratories of Yamaha, which enables the reverberation to be up to 3.0 seconds.
It was possible to experience a change in the reverberation time while auditioning a session of a duo of an acoustic piano and a soprano singer.
The hall is on the 8th floor, and control room and recording studio in the 2nd floor below the ground level are tied with the Ether Sound digital network circuit.