Accession Number : ADA188661

Title :   Time-Frequency Representations for Speech Signals.

Descriptive Note : Doctoral thesis,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE ARTIFICIAL INTELLIGENCE LAB

Personal Author(s) : Riley, Michael D

PDF Url : ADA188661

Report Date : Jun 1987

Pagination or Media Count : 153

Abstract : This work addresses two related questions. The first question is what joint time-frequency energy representations are most appropriate for auditory signals, in particular, for speech signals in sonorant regions. The quadratic transf for the representation: (1) shift-invariance, (2) positivity, (3) superposition, (4) locality, and (5) smoothness. The second question addressed is how to obtain a rich, symbolic description of the phonetically relevant features om these time-frequency energy surfaces, the so-called schematic spectrogram Time-frequency ridges, the 2-D analog of spectral peaks, are one feature that is proposed. If non-oriented kernels are used for the energy representation, then the ridge tops can be identified with zero-crossings in the inner project of the gradient vector and the direction of greatest downward curvature. If oriented kernels are used, the method can be generalized to give better orientation selectivity (e.g., intersecting ridges) at the cost of poorer time-frequency locality.

Descriptors :   *AUDITORY SIGNALS, *SIGNAL PROCESSING, *SPEECH ANALYSIS, COSTS, CURVATURE, DYNAMICS, ENERGY, FREQUENCY, RIDGES, SCHEMATIC DIAGRAMS, SIGNALS, SPECTRA, SPECTROGRAPHY, SPEECH, SURFACES, TIME, ARTIFICIAL INTELLIGENCE, PHONETICS, VOWELS, FEMALES, VOICE COMMUNICATIONS, TRANSITIONS, TRANSFORMATIONS(MATHEMATICS), TWO DIMENSIONAL, KERNEL FUNCTIONS, SPECTRA, THESES

Subject Categories : Voice Communications
      Cybernetics

Distribution Statement : APPROVED FOR PUBLIC RELEASE