1. A microphone array comprising: a first virtual microphone comprising a first combination of a first microphone signal and a second microphone signal, the first virtual microphone having a first linear response to speech and a first linear response to noise, the first linear response to speech being substantially similar across a plurality of frequencies for a speech source located at an angle relative to an axis of the microphone array, wherein the first microphone signal is generated by a first physical microphone and the second microphone signal is generated by a second physical microphone; and a second virtual microphone comprising a second combination of the first microphone signal and the second microphone signal, the second virtual microphone having a second linear response to speech and a second linear response to noise, the second linear response to noise being substantially similar to the first linear response to noise, and the second linear response to speech being substantially dissimilar to the first linear response to speech, wherein at least one of the first linear response to noise and the second linear response to is being non-zero in a direction towards a source of noise.