Masashi Ito Keiji Ohara Akinori Ito Masafumi Yano An effect of formant amplitude in vowel perception. 2490-2493 2010 INTERSPEECH http://www.isca-speech.org/archive/interspeech_2010/i10_2490.html conf/interspeech/2010 db/conf/interspeech/interspeech2010.html#ItoOIY10