Akihiro Hirano

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A robust adaptive microphone array (RAMA) using a new adaptationmode control method (AMC) is proposed, and its evaluation results by hardware are presented. The adaptation of the RAMA is controlled based on an SNR (signal-to-noise) estimate using the output powers of the fixed beamformer and the adaptive blocking matrix. The RAMA is implemented on a(More)
This paper proposes a new robust adaptive beamformer applicable to microphone arrays. The proposed beamformer is a generalized sidelobe canceller (GSC) with a variable blocking matrix using coefficient-constrained adaptive filters (CCAFs). The CCAFs, whose common input signal is the output of a fixed beamformer, minimize leakage of the target signal into(More)
In this paper, a multilayer neural network is applied to 'Brain Computer Interface' (BCI), which is one of hopeful interface technologies between humans and machines. Amplitude of the FFT of the brain waves are used for the input data. Several techniques have been introduced for pre-processing the brain waves. They include segmentation along the time axis(More)
This paper presents convergence characteristics of stereophonic echo cancellers with pre-processing. The convergence analysis of the averaged tap-weights show that the convergence characteristics depends on the relation between the impulse response in the far-end room and the changes of the pre-processing filters. Examining the uniqueness of the solution in(More)
This paper proposes a stereophonic acoustic echo canceller with randomly time-varying second-order pre-processing filters. A quantitative approach for the convergence speed assessment by using time-averaged correlation matrix is also introduced. Simulation results show that the convergence speed of the proposed algorithm is more than twice as fast as that(More)
This paper proposes a stereo echo canceller with simultaneous input-sliding and sliding-period control. Periodic delays with different phases in two channels provide an additional condition for echo cancellation, leading to faster convergence. It also guarantees symmetrical shifts of a sound image around its original position for better subjective quality(More)