2,987 research outputs found
A new perceptual and adaptive quantization method for live spectral frequency parameters based on noise-to-mask ratio
No full textNatural quality two-band LPC coding of speech at 880 bit/s with frame interpolation
No full textA novel frame interpolation technique for two-band linear predictive coding (LPC) vocoders is proposed for maintaining natural speech quality at bit rates below I kbit/s. Experimental results show that the speech quality of the proposed vocoder is quite natural at bit rates 880 bit/s and comparable to that of 4.8 kbit/s CELP
A new band-splitting method for two-band speech model
No full textIn this letter, a new band-splitting method for two-band speech model is proposed, whereby a score function based on the subband periodicity is calculated for each harmonic band and the band of maximum score is selected as the band-splitting frequency. Using the score function, tracking technique is applied to the algorithm for the continuity of the band-splitting frequencies between neighboring frames. This method has proven to be robust to the inaccuracy of pitch estimation and the frequency resolution problem in low-pitched speech
Fiber-optic sensor array based on Sagnac interferometer with stable phase bias
No full textWe propose and experimentally demonstrate a novel fiber sensor array based on Sagnac interferometer with very simple electronic signal processing. A stable quadrature phase bias was obtained using a phase modulator, and polarization-induced signal fading was suppressed by using a depolarizer and a broad-band source, Phase sensitivity of about 4.0 mu rad(rms)/root Hz at 5 kHz was obtained using a two-sensor array
Perceptual adaptive multiband excitation coder using masking properties of human ear
No full textA new multiband excitation ender that exploits the characteristics of human auditory perception is described. In the proposed method, all model parameters are estimated and quantised by utilising the noise-to-mask ratio. Experimental results show that the proposed method can reduce the perceptual distortion significantly at much lower bit rates
Multicodebook split vector quantization of LSF parameters
No full textA multicodebook quantization method for improving the performance of the split vector quantization (SVQ) is described. In the proposed method, multiple codebooks having different sizes are trained, and the minimal-size codebook and its codeword satisfying the condition based on the spectral distortion are determined. Several clustering techniques for reducing total bit rate and the analysis of the computational complexity are also presented. Experimental results have shown that the proposed method reduces the number of outliers significantly and achieves a better rate-distortion performance compared with the fixed-bit-rate SVQ, multistage VQ, and variable-bit-rate SVQ
A tension split Hopkinson bar for investigating the dynamic behavior of sheet metals
No full textThe dynamic response of sheet metals at high strain rate is investigated with a tensile split Hopkinson bar test using plate type specimens. The tension split Hopkinson bar inevitably causes some errors in the strain at grips with the plate type specimens, since the grip and specimens disturb the one-dimensional wave propagation in bars. To validate the experiment, the level of error induced from the grips is estimated by comparing the waves acquired from experiments with the Pochhammer-Chree solution. The optimum geometry of the specimen is determined to minimize the loading equilibrium error. High strain rate tensile tests are then performed with auto-body sheet metals in order to construct their appropriate constitutive models for use in crash-worthiness evaluation
Mixed Multi-band Excitation Coder Using Frequecy Domain Mixture Function(FDMF) for a Low Bit-rate Speech Coding
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Variable Rate Vector Quantization of LSF Parameters Based on Perceptual Distance Measure
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