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Abstract: This paper provides an introduction to the acoustic–phonetic structure of English regional accents and presents a signal processing method for the modeling and transformation of the acoustic correlates of English accents for example from British English to American English. The focus of this paper is on the modeling of intonation and duration correlates of accents as the modeling of formants is described in previous papers (). The intonation correlates of accents are modeled with the statistics of a set of broad features of the pitch contour. The statistical models of phoneme durations and word speaking rates are obtained from automatic segmentation of word/phoneme boundaries of speech databases. A contribution of this paper is the use of accent synthesis for comparative evaluation of the causal effects of the acoustic correlates of accent. The differences between the acoustics–phonetic realizations of British Received Pronunciation (RP), Broad Australian (BAU) and General American (GenAm) English accents are modeled and used in an accent transformation and synthesis method for evaluation of the influence of formant, pitch and duration on conveying accents. [Copyright &y& Elsevier]

This paper presents a speech enhancement method based on the tracking and denoising of the formants of a linear prediction (LP) model of the spectral envelope of speech and the parameters of a harmonic noise model (HNM) of its excitation. The main advantages of tracking and denoising the prominent energy contours of speech are the efficient use of the spectral and temporal structures of successive speech frames and a mitigation of processing artefact known as the ‘musical noise’ or ‘musical tones’. The formant-tracking linear prediction (FTLP) model estimation consists of three stages: (a) speech pre-cleaning based on a spectral amplitude estimation, (b) formant-tracking across successive speech frames using the Viterbi method, and (c) Kalman filtering of the formant trajectories across successive speech frames. The HNM parameters for the excitation signal comprise; voiced/unvoiced decision, the fundamental frequency, the harmonics’ amplitudes and the variance of the noise component of excitation. A frequency-domain pitch extraction method is proposed that searches for the peak signal to noise ratios (SNRs) at the harmonics. For each speech frame several pitch candidates are calculated. An estimate of the pitch trajectory across successive frames is obtained using a Viterbi decoder. The trajectories of the noisy excitation harmonics across successive speech frames are modeled and denoised using Kalman filters. The proposed method is used to deconstruct noisy speech, de-noise its model parameters and then reconstitute speech from its cleaned parts. Experimental evaluations show the performance gains of the formant tracking, pitch extraction and noise reduction stages. [Copyright &y& Elsevier]

In this paper, the probability distribution functions (pdf's) of the formant spaces of three major accents of the English language, namely, British Received Pronunciation (RP), General American, and Broad Australian, are modeled and compared. The statistical differences across the formant spaces of these accents are employed for accent conversion. An improved formant tracking method, based on linear prediction (LP) feature analysis and a two-dimensional hidden Markov model (2-D-HMM) of format trajectories, is used for estimation of the formant trajectories of vowels and diphthongs of each accent. Comparative analysis of the formant spaces of the three accents indicates that these accents are partly conveyed by the differences of the formants of vowels. The estimates of the probability distributions of the formants for each accent are used in a speech synthesis system for accent conversion. Accent synthesis, through modification of the acoustic parameters of speech, provides a means of assessing the perceptual contribution of each formant parameter on conveying an accent. The results of perceptual evaluations of accent conversion illustrate that formants play an important role in conveying accents. [ABSTRACT FROM AUTHOR]