IEEE Transactions on Acoustics, Speech, and Signal Processing

It seems that there is much confusion and misunderstanding with respect to the nature of helium speech and in the design of helium speech unscramblers. This is due to the lack of collective studies covering not only physical properties but also human factors. Some comments on the problem are presented on the basis of author's own experimental results. View full abstract»

Different fast Fourier transform (FFT) algorithms for hardware implementation have been considered. We propose an implementation whereby two radix-N1/2passes are carried out in parallel and in which each N1/2-point transform is carried out via a serial input parallel output transform circuit. The processing rate is one clock cycle per input point for the N-point transform reg... View full abstract»

Although much has been learned about the relationships between design parameters for finite impulse-response (FIR) low-pass digital filters, very little is known about the relationships between the parameters of multiband filters. Thus given a set of design specifications for a multiband FIR filter (e.g., filter band edge frequencies and desired ripples in each of the bands) it is difficult to cho... View full abstract»

A new approach to the implementation problem of digital filters is presented. This approach capitalizes on recent advances in semiconductor memory technology and is shown to offer significant reductions in cost and power consumption for the same speed of operation as that of existing realizations. Furthermore, this approach makes possible speeds of operation which cannot be achieved by existing re... View full abstract»

The delta modulation (DM) of signals which are already in digital form is of interest in a variety of signal-processing applications. It is shown that a delta modulator for digital inputs may be usefully interpreted as a process of slope bias, accumulation, and overflow detection leading to designs which are simpler than those based on analog techniques. Applications are discussed including a divi... View full abstract»

In this paper a fast algorithm for the transformation of the logical autocorrelation function to the arithmetic autocorrelation function is derived, and a computationally efficient procedure for estimating an arithmetic autocorrelation function via fast Walsh transform (FWT) techniques is described. The savings in computer time over straightforward lagged-product computations or the fast Fourier a... View full abstract»

In this paper we describe an application of a real-time isolated-word recognition system, to the recognition of sentences of a language used in numerical command of machine tools. The acoustic level operates with dynamic matching procedure and knowledge about syntactics and semantics of the language is used to predict the incoming words. With such a syntax-directed system, real-time recognition of... View full abstract»

Recent work by Thajchayapong and Rayner [1] demonstrated a technique for designing recursive infinite impulse response (IIR) digital filters by linear programming. By using an algorithm, described by Barrodale et al. [2], the differential correction algorithm, we will show how one may obtain optimum rational approximations to a given magnitude-squared frequency response in the Chebyshev norm. This... View full abstract»

The application of the "branch and bound" technique for nonlinear discrete optimization, due to Dakin, to the problem of finding the coefficients of a recursive digital filter with prescribed number of bits, to meet arbitrary response specifications of the magnitude characteristic, is investigated. Due to the fact that the objective function is nonlinear and the stability constraints are linear wi... View full abstract»

The digital filtering of two-dimensional signals offers the many advantages characteristic of digital computers, such as flexibility and accuracy. Applications exist in the processing of images and geophysical data. A technique is presented for designing stable two-dimensional recursive filters whose magnitude response is approximately circularly symmetric. This is achieved by cascading a number o... View full abstract»

The exact impulse response of field parameters for any field point on or off axis for the case where a circular disc radiator face is subjected to a displacement step corresponding to a velocity impulse is reviewed. By convolution, the transient field pattern for any arbitrary motion of the disc can be obtained. The exact response for a half-sine monopulse is computed. An approximate representatio... View full abstract»

The purpose of this paper is to present the theoretical differences and results of experimental comparison of the stationary (autocorrelation) and nonstationary (covariance) linear prediction formulations when applied to voiced speech analysis. In this experimental study three criterion used for comparison purposes are: 1) total minimum normalized squared error, 2) accuracy in estimating speech sp... View full abstract»