How Does An Electret Condenser Microphone Work? 

Microphones convert sound energy (sound waves) to electrical energy (an audio signal).  An electret condenser microphone (ECM) consists of two plates, one fixed (back plate) and one moveable (diaphragm).  There is a small gap between each plate and when sound waves hit the diaphragm, the movement causes the capacitance between the diaphragm and the back plate to change.  This generates a flow of variable electric current and these electrical signals are sent to the designated output device.

A permanently charged electret material, either on the diaphragm or back plate, means that ECMs do not need a constant source of electrical charge making them very efficient and economical.

Typical electret condenser microphone circuit diagram –

Electrical connections are made either by PCB pins, leads or solder joints.

ECM Directionality – this is a microphone’s sensitivity to sound from various directions:

• Omnidirectional microphones are microphones designed to pick up sound equally from all directions—360 degrees around the microphone. Unlike unidirectional microphones, which capture sound primarily from one direction (typically from the front), omnidirectional mics have a wider, more uniform sensitivity to sound. This makes them highly versatile in many recordings and audio-capture scenarios.
  These microphones do not favour any particular direction, making them ideal for situations where sound needs to be recorded from multiple sources around the mic or in a natural, environment-friendly way.
• Uses:
  o Field recording
  o Capturing natural ambience
  o Roundtable discussions

• Noise-cancelling microphones are specialized microphones designed to reduce or eliminate unwanted ambient noise from the audio signal, making the desired sound (typically voice) clearer and more intelligible. They’re used in various applications where background noise can interfere with the quality of recordings or communications, such as in telephones, headsets, and professional audio equipment.
  This technique uses electronic circuitry to create a sound wave that is the exact inverse (anti-phase) of the unwanted noise. When the anti-phase sound wave interacts with the unwanted noise, they cancel each other out. This process effectively reduces low-frequency background noise, like hums or engine noise.
• Uses.
  • Reduces background chatter, typing, and AC noise
  • Ensures clear communication for customer support or remote work
  • Headsets with built-in DSP (Digital signal processing)
  • Cockpit headsets and helmets
  • Cuts out engine noise, wind, and cockpit ambient sounds
  • Suppresses fan, keyboard, and room noise
  • Allows streamers or gamers to communicate clearly
• Unidirectional microphones are microphones that are designed to pick up sound predominantly from —usually from the front—while rejecting sound from the sides and rear. These microphones are essential in many applications where the goal is to isolate a specific sound source from the surrounding environment.  This defines how the microphone picks up sound from different directions. Unidirectional microphones come in various polar patterns, each offering different degrees of directionality.
• Uses.
  • Isolates the speaker’s voice
  • Reduces room noise and echo
• Avoids picking up background noise like fans, keyboards, or other people

Applications –

ECMs are widely used to enable communication and recording as they are inexpensive and offer good performance.  Key applications include:

• Telephones
• Smartphones
• Desk top computers
• Tablets
• Headsets
• Hearing aids
• PDAs
• Access control systems
• Lift controls
• Parking meters
• Surveillance equipment
• Audio visual products

Microphones with IP67 Rating

We offer microphones with an IP67 rating for the aperture of the microphone

For more information on our extensive range of electret condenser microphones, visit our website at https://www.abcomponents.co.uk/electret-condenser-microphones/ or call 01258 456360.  We are able to customise our standard microphones by changing the lead length or type of connection and we will be happy to discuss this with you.