Hello! Just curious, can a MEM microphone can create feedback noise? How come my phone never creates feedback noise when mic and speaker are so close to each other? Response will be appreciated!

 

All microphones are susceptible to feedback.
Echo, feedback and noise cancellation is performed in software.

 

A handsfree (loud speaking) telephone or intercom has its speaker loud enough to produce feedback when the mic hears it. So it uses a manual switch for press-to-talk or it uses an electronic circuit to turn on the mic and turn off the speaker for "voice-switching". But background sounds usually mess-up voice-switching. Manual or voice-switching never allows both ends to talk and listen at the same time.

 

I'm pretty sure my cordless POTS phone allows simultaneous talking and listening when using the speaker, so it must have some electronic method of doing that.

 

If a circuit accurately matches the varying amount of impedance and phase shift of a telephone line then it can cancel what is transmitted from being received, which cancels feedback.

Motorola made an IC years ago that did pretty good voice switching of a loudspeaking telephone or intercom. It even adjusted itself so that background noise did not "hog" a voice direction.

Polycom and others make some loudspeaking telephones that prevent feedback but allow "full duplex" by using a digital echo-cancelling circuit. Sometimes the echo cancelling circuit got confused and produced weird sounds.

 

All microphones are susceptible to feedback.
Echo, feedback and noise cancellation is performed in software.

Hello, thank you for the answer. Good to know it is all done through software.

 

A handsfree (loud speaking) telephone or intercom has its speaker loud enough to produce feedback when the mic hears it. So it uses a manual switch for press-to-talk or it uses an electronic circuit to turn on the mic and turn off the speaker for "voice-switching". But background sounds usually mess-up voice-switching. Manual or voice-switching never allows both ends to talk and listen at the same time.

Thank you for mentioning about voice switching. Will definitely look more into this!

 

I'm pretty sure my cordless POTS phone allows simultaneous talking and listening when using the speaker, so it must have some electronic method of doing that.

Thank you for the response.