A cardioid microphone, also known as a unidirectional microphone, mainly records sound from 1 direction. Cardioid microphones are very sensitive at the front and limited at the rear. This means that you only register the sound source and you avoid recording reflections through the walls. You choose a cardioid microphone with hot shoe adapter when you combine the microphone with your video or photo camera. A model with USB port is ideal for recording podcasts, voice overs, and streams.