In terms of speech recognition, two microphones are better than one, and sound waves
reaching multiple microphones can exhibit varying degrees of time delay, which can be used to
enhance the intensity of signals from a particular direction while reducing signals from other
Researchers at the Amazon Alexa division have developed a novel acoustic modeling
framework that enhances performance through unified speech enhancement and speech
recognition. They used a dual-microphone system in their experiments, compared to systems
that used seven microphones. They said the new system reduced the error rate of speech
recognition by 9.5%.