In this paper, a method for two-sound-source tracikng is proposed based on speech spaseness. In our previous work, the two-sound-source tracking method was introduced using two successive algorithms, i.e., PAST (Projection Approximation Subspace Tracking) and IPLS (Interior Point Least Square) . In the method, appropriate initial values for the IPLS algorithm are required. In the proposed method, a weighted histogram of the DOA (Direction of Arrival) estimation results in time-frequency region is used for determining the appropriate initial values. Several experimental results in an actual environment are shown to verify the effectiveness of the proposed method.

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In this paper, we propose the method which improves the speech recognition accuracy on acoustically similar words in Japanese. For example, when there is a different consonant in two acoustically similar words where the sequences of their vowels are same, it is difficult to recognize them correctly under noise circumstances. In the proposed system, after a conventional HMM-based noise robust speech recognition is applied, the acoustic difference in these words is estimated and then noise robust speech recognition is again applied for their precise speech features. As a result, it is shown that the recognition accuracy can be improved under noise environments.

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A lossless transmission line of length l is called a unit element. By showing numerical examples, we demonstrate that resonance and eigen-oscillation can be obtained using a unit element as a circuit element. Because resonance and eigen-oscillation are responses in the steady state, the transient response that occurs until the circuit reaches the steady state should be considered. Although the transient response has been conventionally considered a phenomenon of exponential attenuation that depends on a time constant, we numerically demonstrate that the transient response of a unit element is a phenomenon of discrete attenuation that can be expressed using a z-transform. In addition, resonance and eigen-oscillation involve reactive power, which is not related to energy, because the transient response of the circuit using a unit element is closely related to the phases expressed by the z-transform. We also numerically show that the reactive power is confined in the circuit.

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