Re: formant filtering (Eckard Blumschein )

Subject: Re: formant filtering
From:    Eckard Blumschein  <Eckard.Blumschein(at)E-TECHNIK.UNI-MAGDEBURG.DE>
Date:    Fri, 28 Feb 2003 08:47:28 +0100

At 21:45 27.02.2003 -0500, Ramdas Kumaresan wrote: >Alain de Cheveigne pointed me to the following. > >de Cheveigné, A. (1999). Formant bandwidth affects the identification >of competing vowels. Proc. ICPhS, 2093-2096, available as: > This paper starts with the words: 'Formant bandwidth is known to have little effect on the quality or intelligibility of isolated vowels'. Look at Fig.1. Don't worry about Hz instead of kHz. Narrowing of bandwidth made about 12 dB(A) more difference between peaks and inter-formant valleys as compared with widening. So the observed effect on mutual masking is bound to a basic assumption: Both competing vowels have the same RMS. This difficulty to have an adequate basis for comparison reminds me of own experience. We tried to use spectral smearing for mitigation of an annoying highly tonal noise which was caused from a pulsed arc due to precise power electronic switching. The method can avoid dangerous mechanical resonance. We were also able to make the acoustic noise less 'cutting'. However, this required to randomize frequency over a considerable range of deviation from its technologically required mean value. We achieved a satisfactory decrease of tonality only on condition this range exceeded the critical bandwidth, while in this case the noise did perhaps not get less annoying but, as expected, even louder. Eckard

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