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Multiple dichotomies in timbre research

Papanikolaou G., Pastiadis C.

Archives of Acoustics

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2009

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Vol. 34, No. 2

137-155

EN

In this paper an overview of aspects, terminology and literature on contemporary research regarding timbre is presented. Timbre is a multidimensional entity, and research traces its multifaceted nature. The paper handles this structural complexity using a domain-task-results paradigm. Several domains of application are examined and various aspects of timbre questioning are outlined, although consideration of aspects in music and its contextual applications are postponed for a following detailed report for reasons of presentation compactness and extent. A self-evident differentiation of research categorization stems from the type of consideration of timbre as a perceptual attribute or as a manifestation of physical (either generative or modified after transmission) phenomena and processes. As more "axes" of differentiation also emerge, this work attempts to highlight issues that rise and propose possible research directions.

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Discrete cosine transform based de-noising of glottal pulses

Pastiadis C., Papanikolaou G.

Archives of Acoustics

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2004

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Vol. 29, no. 1

35-43

EN

Reliable estimates of the glottal function are of major importance in speech/voice processing for the characterization of voicing conditions, description of various phonation types, and identification of their parameters. This paper presents a new method for de-noising glottal wavelets (Differentiated Glottal Volume Velocity Pulses) and separation of the noise component, based on an approximation of their Discrete Cosine Transform as a sum of Exponentially Damped Sinusoids. The identification of the Exponentials' parameters leads to convenient estimation of ''clean'' glottal wavelets and thus separation of noise disturbances. The method is compared to standard Low-pass filtering and Wavelet de-noising using Monte Carlo simulations on synthetic Liljencrants-Fant glottal pulse models. As shown, the method supercedes for lower SNRs. Moreover, the method does not require exact determination of control parameters thus offering ease of implementation.

3

A preliminary study on greek esophageal speech and a method for quality and intelligibility enhancement

Pastiadis C., Papanikolaou G.

Archives of Acoustics

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1999

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Vol. 24, no. 1

25-38

EN

The present work is a preliminary study on Greek esophageal speech and is mainly concerned with the investigation of major features such as pitch, formant frequencies, and speech power envelopes. The implementation in esophageal speech of various well-known techniques for normal voice analysis is overviewed. An improved method for resynthesizing voiced sounds (such as vowels or nasal consonants) by convolution of an ARMA estimate of the speaker's vocal tract impulse response and a periodic glottal waveform is proposed as a tool for voice quality enhancement. Fundamental frequency values were confirmed to be close to previous works' findings. Fl and F2 formant alterations due to laryngectomy were not detected compared to normal speech values. However, speech power envelopes tended to be flatter as the speaker's training stage was higher. The proposed method for speech enhancement proved able enough to preserve speaker characteristics and provide cues for higher quality reproduction of vowels as well as nasals.