INTERSPEECH 2012
13th Annual Conference of the International Speech Communication Association

Portland, OR, USA
September 9-13, 2012

Making Conversational Vowels More Clear

Seyed Hamidreza Mohammadi, Alexander Kain, Jan P. H. van Santen

Center for Spoken Language Understanding, Oregon Health & Science University, Portland, OR, USA

Previously, it has been shown that using clear speech short-term spectra improves the intelligibility of conversational speech. In this paper, a speech transformation method is used to map the spectral features of conversational speech to resemble clear speech. A joint-density Gaussian mixture model is used as the mapping function. The transformation is studied in both the formant frequency and the line spectral frequency domains. Listening test results show that in noisier environments, the transformed speech signal improves vowel intelligibility signif- icantly compared to the original conversational speech. There is also an increase in vowel intelligibility in less noisy environ- ments, but the increase is not statistically significant. The significance tests are performed by Tukey comparison and planned one-tail t-test methods.

Index Terms: conversational speech, clear speech, speech transformation, intelligibility

Full Paper

Bibliographic reference.  Mohammadi, Seyed Hamidreza / Kain, Alexander / Santen, Jan P. H. van (2012): "Making conversational vowels more clear", In INTERSPEECH-2012, 643-646.