title: Envelope expansion methods for speech enhancement.
abstract: The last decade has seen increasing interest in techniques for the enhancement of digital speech signals. Significant gains have been made in terms of signal-to-noise ratio (SNR) and quality, but few techniques have produced improvements in intelligibility. A method for speech enhancement based on nonlinear expansion of the spectral envelope is presented. The expansion is consistent with both the long-term spectrum of the speech and with the probability that speech is present in a given sample. Objective SNR measures are used to compare this algorithm with the well-known spectral subtraction method, with an alternative expansion scheme, and with limiting SNRs resulting from perfect recovery of the amplitude spectrum. For the purpose of intelligibility assessments, a simplified version of the algorithm has been implemented on a Texas Instruments TMS320-C25 system. Listening trials with this real-time system, conducted using a modified rhyme test, have produced small, but consistent, improvements in articulation scores.
authors.affiliation: Electrical and Computer Engineering Department, Illinois Institute of Technology, Chicago 60616.
authors.forename: P M
authors.initials: PM
authors.lastname: Clarkson
authors.forename: S F
authors.initials: SF
authors.lastname: Bahgat
mesh_terms: D000162:Acoustics; D000465:Algorithms; D008722:Methods; D013065:Speech Intelligibility