When testing noise, the commonly used directional microphones include cardioid, supercardioid, hypercardioid (shotgun), and omnidirectional microphones.
Note: Cardioid, supercardioid, and hypercardioid microphones are often referred to as unidirectional microphones, while omnidirectional microphones are known as all-direction microphones. The figure-eight pattern microphone is categorized as a bidirectional microphone.
Cardioid Microphone
This traditional directional microphone has a moderate pickup pattern and interference rejection capabilities, making it suitable for measuring stable sound sources.
Supercardioid Microphone
A relatively newer type, the supercardioid microphone features a highly directional pickup pattern and superior interference rejection. Its main advantage is its ability to minimize the effects of reflected sound, making it ideal for measuring sound propagation and reflection in complex environments. However, it is essential to maintain a constant orientation between the microphone and the sound source to avoid measurement errors.
Hypercardioid Microphone
This type offers strong directionality and interference rejection, making it suitable for measuring distant sound sources. However, due to its narrow pickup pattern, it requires precise alignment with the sound source to ensure accurate measurements.
Omnidirectional Microphone
Capable of capturing sound from all directions, the omnidirectional microphone is ideal for measuring ambient noise and nearby sound sources. However, its lack of directionality makes it susceptible to interference from the surrounding environment.
Microphone Directionality Considerations
When choosing a directional microphone for noise testing, it's crucial to consider the specific requirements of your measurement situation:
- For measuring distant sound sources or sound distribution in complex environments, a supercardioid microphone is recommended.
- For stable sound sources, a cardioid microphone would be appropriate.
- For distant sound sources, opt for a hypercardioid microphone.
- To measure environmental noise, an omnidirectional microphone should be used.
