Annie (Wei) Dai from Cornell University sent in this Vowel Voice Decoder System she did for the ECE 4760 Class.
“The audio input is sampled through a microphone/amplifier circuit and analyzed in real time using the Mega644 MCU. The user can record and analyze his/her speech using both hardware buttons and custom commands through PuTTY. In addition, the final product also supports a simple voice password system where the user can set a sequence of vowels as password to protect a message via PuTTY. The message can be decoded by repeating the same sequence via the microphone.”