Publication: IEICE TRANSACTIONS on Information and Systems Publication Date: 2010/09/01 Vol. E93-DNo. 9pp. 2472-2482 Type of Manuscript: Special Section PAPER (Special Section on Processing Natural Speech Variability for Improved Verbal Human-Computer Interaction) Category: Voice Conversion Keyword: laryngectomees, esophageal speech, speech enhancement, voice conversion, eigenvoice conversion,