Field Generation System Research Articles

Sound field generation system

A signal of a whole audio frequency band is input to input lines CHL and CHR having band-split digital band pass filters BFL1 to BFLn and BFR1 to BFRn, attenuators ATL1 to ATLn and ATR1 to ATRn, delay elements ZL1 to ZLn and ZR1 to ZRn, and adders 21 to 24, thereby causing speakers 25 and 26 to generate sounds. The reproduced sounds are picked up by microphones 27 and 28 placed at listening positions. The obtained pick-up signals PR and PL are passed through band-split digital band pass filters BFL1′ to BFLn′ and BFR1′ to BFRn′ which are set to the same bands as those of the band-split digital band pass filters BFL1 to BFRn, to generate test data DL1(t) to DLn(t) and DR1(t) to DRn(t). On a basis of the test data, an interaural correlation coefficient ρRL is calculated. Attenuation factors of the attenuators, and delay times of the delay elements are adjusted so as to approximate the interaural correlation coefficient ρRL to a target interaural correlation coefficient ρRL′ which is previously acquired on a basis of a transfer function of a target reproduced sound field.

Opportunities and challenges for private industry

With the orderly entry of private firms into the business of volume greenhouse tuber production derived from meristem/tissue culture programs, the industry as a whole should see a continuing reduction in the number of field seed generations required to supply the commercial grower with certified seed. The further reduction in field generations will be aided by product push and market pull with quality potato seed being supplied at the beginning of the field generation system and the commercial growers demanding access to earlier generation material as commercial seed. This process is already in motion and should begin to accelerate once adequate knowledge of product performance is available to the seed potato industry members. Potato variety quality should continue to improve rapidly with the availability of new laboratory based technologies that accelerate the identification of new genetic material for evaluation and introduction. A more comprehensive integration of field and laboratory plant breeders has begun and should continue at a rapid pace. Each has an important role to play in the development of new improved germplasm for the industry. Automated tissue culture production systems are very close at hand and should have a direct impact on cost of production. These robotic breakthroughs will also contribute to more cost efficient production systems for greenhouse tubers.