Where to point the microphone?
Different microphones have different pickup patterns. These patterns are 3D but can be represented on a type of graph called a polar plot. This type of graph lets you see a slice of the pickup pattern from different angles to give you an idea of what the pattern looks like. The other issue is that the pickup pattern often varies with frequency – so there will be multiple traces on the polar plots to show you what shape its pickup pattern will be at different frequencies. Why have different pickup patterns? Because different microphones can be used for different things. You might want to only pickup sound from a certain direction, and reject sound form others. You might want to put the microphone further away from a sound source and still pickup a good level from the source.
The pictures below give you an idea of some of the commonly used pickup patterns.
Omnidirectional
Omnidirectional microphones pickup sound coming from any direction. Interestingly, most head worn microphones in theatre are actually omnidirectional. Quite a lot of the sound they pickup comes from vibrations going through the actor skull – bone conduction. Sometimes, having a more directional microphone on someones face can cause more problems if it ends up pointing in the wrong direction.
Cardioid
The following picture from Shure Microphones is a great 3D representation of how the microphone will pick-up sound. You can see that the microphone is less sensitive the sound form behind the capsule – the part that you hold/attach to a stand. You can see it is most sensitive in front of the microphone, where you would sing into it. As you move from directly in front of the capsule, the sensitivity begins to drop off. Hopefully you can see how the 3D picture translates to the 2D pattern above.
Supercardioid & Hypercardioid
Supercardioid is a progression of Cardioid. It is even more sensitive in front of the capsule and less so at the sides. However the drawback of this is it begins to pickup sound directly behind the capsule – which could translate into handling noise if holding it. Hypercardioid is a further extension on this. This type of microphone is also known as a shotgun microphone – typically used in TV & Film by a ‘Boom Operator’ that has the microphone on a boom pole above the actors to pick up the dialogue in a scene. Not exactly practical in a theatre, but they are sometimes used to pickup dialogue on a stage.
