tailieunhanh - Báo cáo khoa học: "VOICE SIMULATION: FACTORS AFFECTING QUALITY AND NATURALNESS"

In this paper we describe a f l e x i b l e analysls-synthesls system which can be used for a number of studies In speech research. The maln objective Is to have a synthesis system whose characteristics can be controlled through a set of parameters to realize any desired voice characteristics. The basic synthesis scheme consists of two steps: Generationof an excitation signal f r o m pitch and galn contours and excitation of the linear system model described by linear prediction coefficients, W show that e a number of basic studies such as time expansion/. | VOICE SIMULATION FACTORS AFFECTING QUALITY AND NATURALNESS B. Yegnanarayana Department of Computer Science and Engineering Indian Institute of Technology Madras-600 036 India . Na1k and . Childers Department of Electrical Engineering University of Florida Gainesville FL 32611 . ABSTRACT In this paper we describe a flexible analysis-synthesis system which can be used for a number of studies In speech research. The main objective Is to have a synthesis system whose characteristics can be controlled through a set of parameters to realize any desired voice characteristics. The basic synthesis scheme consists of two steps Generation of an excitation signal from pitch and gain contours and excitation of the linear system model described by linear prediction coefficients. We show that a number of basic studies such as time expansion compression pitch modifications and spectral expansion compresslon can be made to study the effect of these parameters on the quality of synthetic speech. A systematic study is made to determine factors responsible for unnaturalness In synthetic speech. It Is found that the shape of the glottal pulse determines the quality to a large extent. We have also made some studies to determine factors responsible for loss of Intelligibility 1n some segments of speech. A signal dependent analysis-synthesis scheme Is proposed to Improve the Intelligibility of dynamic sounds such as stops. A simple Implementation Of the signal dependent analysis Is proposed. I. INTRODUCTION The main objective of this paper is to develop an analysis-synthesis system whose parameters can be varied at will to realize any desired voice characteristics. This will enable us to determine factors responsible for the unnatural quality of synthetic speech. It is also possible to determine parameters of speech that contribute to Intelligibility. The key Ideas 1n our basic system are similar to the usual linear predictive LP coding vocoder 1 2 Our main contributions to the