Evaluating Noise Rejection Performance Of Microphones With Different Polar Patterns And Frequency Response In Different Noise Environments

The purpose of this experiment is to evaluate the noise rejection performance of omni-directional, cardioid and bi-directional (noise cancelling) microphones in simulated noisy environments.

3 microphones with different polar responses were tested on their performance in various noisy environments:

• Omni-Directional Microphone with flat frequency response (peak at around 10-12kHz)
• Bi-Directional (Noise-Cancelling) Microphone
• Cardioid Microphone

The simulated noise environments are:

• Traffic noise at 90dB
• Helicopter noise at 106dB
  * Noise is measured in C-weighting

The experiment was carried out in IntriCon’s test room. The “human” voice is produced via a B&K 4227 artificial voice, placed in the centre of the room and surrounded by 8 loudspeakers. Noise is generated through all loudspeakers to achieve the desired sound level right in front of the artificial mouth (lip ring). Voice output from the artificial mouth is set at an average of 94dB (C-weighted) at the lip-ring position.

Diagram showing setup of experiment

Basic information on the various microphones used

Audio recordings taken from the output of these respective microphones

 

Wave forms of recorded signal