Patents by Inventor Katsumasa Nagahama

Katsumasa Nagahama has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20130142343
    Abstract: With conventional source separator devices, specific frequency bands are significantly reduced in environments where dispersed static is present that does not come from a particular direction, and as a result, the dispersed static may be filtered irregularly without regard to sound source separation results, giving rise to musical noise. In an embodiment of the present invention, by computing weighting coefficients which are in a complex conjugate relation, for post-spectrum analysis output signals from microphones (10, 11), a beam former unit (3) of a sound source separator device (1) thus carries out a beam former process for attenuating each sound source signal that comes from a region wherein the general direction of a target sound source is included and a region opposite to said region, in a plane that intersects a line segment that joins the two microphones (10, 11).
    Type: Application
    Filed: August 25, 2011
    Publication date: June 6, 2013
    Applicant: ASAHI KASEI KABUSHIKI KAISHA
    Inventors: Shinya Matsui, Yoji Ishikawa, Katsumasa Nagahama
  • Patent number: 8112272
    Abstract: A sound source signal from a target sound source is allowed to be separated from a mixed sound which consists of sound source signals emitted from a plurality of sound sources without being affected by uneven sensitivity of microphone elements. A beamformer section 3 of a source separation device 1 performs beamforming processing for attenuating sound source signals arriving from directions symmetrical with respect to a perpendicular line to a straight line connecting two microphones 10 and 11 respectively by multiplying output signals from the microphones 10 and 11 after spectrum analysis by weighted coefficients which are complex conjugate to each other. Power computation sections 40 and 41 compute power spectrum information, and target sound spectrum extraction sections 50 and 51 extract spectrum information of a target sound source based on a difference between the power spectrum information.
    Type: Grant
    Filed: August 11, 2006
    Date of Patent: February 7, 2012
    Assignee: Asashi Kasei Kabushiki Kaisha
    Inventors: Katsumasa Nagahama, Shinya Matsui
  • Publication number: 20090055170
    Abstract: A sound source signal from a target sound source is allowed to be separated from a mixed sound which consists of sound source signals emitted from a plurality of sound sources without being affected by uneven sensitivity of microphone elements. A beamformer section 3 of a source separation device 1 performs beamforming processing for attenuating sound source signals arriving from directions symmetrical with respect to a perpendicular line to a straight line connecting two microphones 10 and 11 respectively by multiplying output signals from the microphones 10 and 11 after spectrum analysis by weighted coefficients which are complex conjugate to each other. Power computation sections 40 and 41 compute power spectrum information, and target sound spectrum extraction sections 50 and 51 extract spectrum information of a target sound source based on a difference between the power spectrum information.
    Type: Application
    Filed: August 11, 2006
    Publication date: February 26, 2009
    Inventor: Katsumasa Nagahama
  • Publication number: 20050043948
    Abstract: A speech recognition method can be preferably applied to equipment for constantly performing speech recognition, converts speech into an acoustic parameter series, calculates for the acoustic parameter series the likelihood of a hidden Markov model 22 corresponding to the speech unit label series about a registered word and the likelihood of a virtual model 23 corresponding to the speech unit label series for recognition of speech other than the registered word, and performs speech recognition based on the likelihoods.
    Type: Application
    Filed: December 17, 2002
    Publication date: February 24, 2005
    Inventors: Seiichi Kashihara, Hideyuki Yamagishi, Katsumasa Nagahama, Tadasu Oishi