Category Archives: Audio

Microphone Feedback

Aside from the cell phone-caused speaker interference, there are additional sources of noise/interference in an audio system, including mic feedback. Here are some more resources that describe ways to reduce feedback:
http://toonz.ca/bose/wiki/index.php?title=Microphone_Feedback
http://www.google.com/search?q=mic+feedback
http://en.wikipedia.org/wiki/Audio_feedback#Directivity
http://www.mediacollege.com/audio/howto/feedback.html
http://www.audiocourses.com/article113.html
http://proavmagazine.com/acoustics/designing-a-mix-minus-distributed-sound-system.aspx
http://en.wikipedia.org/wiki/Microphone#Microphone_polar_patterns
http://www.ccisolutions.com/worshiptools/learn-about-microphone-feedback

http://www.shure.com/idc/groups/public/documents/webcontent/us_pro_mics_for_music_sound_ea.pdf
http://www.shurenotes.com/issue23/article.html
http://www.shurenotes.com/issue27/article.html

http://www.dt4u.com/dtsystems/feedback.php
http://boards.straightdope.com/sdmb/archive/index.php/t-34057.html
http://www.behringer.com/EN/Products/FBQ2496.aspx
http://www.mp3backingtrax.com/article56.htm

Shielding Audio Equipment from Cell Phone Interference

In the words of Gary Guinn (AKG Acoustics), “The past two years have brought a whirlwind of engineering nightmares with Blackberry and other wireless units creating problems in wired and wireless microphones.” http://www.crownaudio.com/kb/entry/163/

Indeed, combining shielded and unshielded wires with wireless phones and other wireless devices can lead to interference and buzz (you can hear samples of the issue http://www.youtube.com/watch?v=sZEMoH2xRfM&t=0m13s, http://www.youtube.com/watch?v=emxPVUM3y54 and http://www.youtube.com/watch?v=HzufTbKiJzw

Solutions have been presented but none are ideal:

Another interesting solution (suggested here):
http://www.neutrik.com/content/products/level03.aspx?id=204_1603252336&catId=CatMSDE_audio
IEEE suggestion (add ferrite cores):
http://www.hottconsultants.com/pdf_files/aes-2007.pdf