Polar patterns describe how microphones pick up sounds. In particular, it describes the sensitivity of the microphone to sound waves as they come from different directions. The directional or polar pattern characteristic of a microphone should be a very important consideration in determining whether a certain microphone is a right or the wrong choice meant for a particular application or situation. Therefore, it is important that sound engineers or fieldrecordists know what the different characteristics are, how they work, and also, in what situations they should be used.
Hypercardioid polar pattern
The hypercardioid polar pattern is a misunderstood relative of the more popular cardioid microphone polar pattern and again, it is confused at times with the supercardioid polar patterns. The Understanding of the hypercardioid polar pattern, its ideal use or application, is sure to improve how you use them and their effectiveness in the studio and on stage.
What is a hypercardioid microphone?
The hypercardioid microphone is a microphone with a very directional or hypercardioid polar pick-up pattern. These microphones are more sensitive to on-axis sounds (the direction where the microphone “points”). It has zero or null point at 110° and 250° and a rear sensitivity lobe. Due to their high directionality, Hypercardioid microphones are quite popular in movies and on stage.
The hypercardioid pickup pattern is an excellent directional pickup pattern for recording isolated audio. Although you may find some lay microphones with hypercardioid pickup patterns, this pickup pattern is usually only obvious on shotgun microphones. Although each brand is different, what is known to be the biggest difference between a supercardioid and a hypercardioid microphone is the amount of rear and side noise that is picked up. Hypercardioid microphones are generally used for the recording of instrumentals.
Cardioid polar patterns (which is the parent polar pattern of hypercardioid polar pattern) has a completely positive polarity for pickups, while the bidirectional is positive at the front and negative at the back.
The hypercardioid pattern is obtained in a similar way to the other unidirectional cardioid polar pattern. i.e. the cardioid and supercardioid patterns. This is done when a carefully designed rear acoustic labyrinth that balances the timing of the sound waves hits the back of the microphone diaphragm.
When two cardioid patterns are superimposed, both rid of the cardioids rear null point and replaces it with a lobe of sensitivity. Also, the side null points of bidirectional patterns are moved toward the rear or back at about 110° and 250°. The result you’d get is something like the hypercardioid pattern.
The acceptance angle of the hypercardioid polar pattern is approximately 150° if we measure a drop of 6dB compared to the reaction on-axis. They are approximately 90° when a difference of 3dB is measured. When compared to a cardioid microphone, the hypercardioid option is very directional.
It is pertinent to note that when the diaphragm of a microphone experiences the same acoustic pressure at the front and rear, it will not move, therefore it will not produce a microphone signal. This is from where the “null points” in the polar patterns are derived.
Null points are established at 110° and 250° on Acoustic labyrinths of the typical hypercardioid capsules.
The sound waves which approach the hypercardioid capsules at 110° and 250° strikes the acoustic labyrinth and may take some time to reach both the rear (through the labyrinth) and the front of the diaphragm (around the external part of the capsule). The sound waves cancel each other out and create a null point in the hypercardioid polar pattern.
What can I use a hypercardioid microphone for?
This polar pattern has a high directionality. The high directionality makes the microphone’s ideal in some situations, but below average in others. So, let’s talk about those instances when using a hypercardioid microphone is better than otherwise, and also, those instances where you may not get the best result in using them.
The following are the best applications for hypercardioid microphones
- This polar pattern is ideal for on-camera microphones, recording of documentaries, and instrumentals.
- In recording films or movies as a boom microphone or a camera mounted microphone (i.e. a moveable microphone).
- In the front of dual monitoring foldback systems used for live sound reinforcement (make sure the monitors are at the null points of the hypercardioid).
- They are used to capture certain sounds in an environment.
- To isolate/close-mic individual sound sources in a noisy environment.
- For picking up sound from closely positioned individual sound sources (such as that of a drum kit).
Pros of the hypercardioid pattern
- The main pro of using the hypercardioids is the stronger off-axis sound rejection.
- There is more lateral rejection.
Cons of the hypercardioid pattern
- The only drawback to these types of microphones with narrower patterns is the more expensive price they’re sold for. This is because they are less useful when a larger capturing is to be done (e.g. it will be difficult for two singers to share the microphone).
- And in addition, there is less rear rejection.