If you downloaded the 1.1 version of BitVoicer, you have to use the BitVoicer11.h library. Also, The code in this sketch is no longer supported by the new version. Use the code in this post instead: Wireless Audio Streaming and Speech Recognition (PART 2) - #7 by leandro4b - Audio - Arduino Forum, but if you are not using an electret microphone, you will have to make some changes to the code.