Common types of microphone directivity used in noise testing include: cardioid, supercardioid, shotgun (highly directional), and omnidirectional.
Note: Cardioid, supercardioid, and shotgun types are generally referred to as unidirectional microphones, while omnidirectional ones are known as non-directional, and bidirectional types are figure-8 pattern mics.
Cardioid Microphones
Cardioid microphones are a traditional type of directional mic. They offer good front sensitivity and moderate side rejection, making them suitable for measuring stable sound sources in relatively controlled environments.
Supercardioid Microphones
These offer a narrower pickup pattern and stronger rejection of ambient noise and reflections. They are ideal for measuring sound behavior in complex environments with multiple reflections. However, they require careful alignment with the sound source to avoid measurement errors.
Shotgun (Highly Directional) Microphones
Shotgun mics have a very narrow pickup angle, making them suitable for capturing distant sound sources. Like supercardioid mics, they require accurate aiming; otherwise, the test results may be inaccurate.
Omnidirectional Microphones
Omnidirectional mics capture sound equally from all directions. They are ideal for measuring ambient noise or close-range sound sources. However, they can also pick up a lot of environmental interference due to their lack of directionality.
How to Choose the Right Mic for Noise Testing?
The choice depends on your specific use case:
- For distant or directional noise sources in complex environments, use a supercardioid mic.
- For stable and consistent sound sources, a cardioid mic is recommended.
- To capture long-distance sources in a straight line, opt for a shotgun mic.
- For ambient noise measurements, go with an omnidirectional mic.
