I have no experience with the CM-i3, but I see by the specs, it's a
cardioid. A
cardioid mic is directional, but is not considered "noise cancelling." A
cardioid has one null in its pickup
pattern but can still
pick up sound from most other directions. Most handheld vocal microphones, such as an
SM58, are cardioids.
A noise cancelling mic is much different. They are a two port device that only picks up sources that are closer to one port compared to the other. They are very effective in noisy places, but have the downside of being picky about placement. The mic has to be right in front of your lips, or your voice will get cancelled along with everything else.
Thank you
@FMEng for 'breaking the ice' on this one.
@John Palmer and yourself are harkening back to what is / was a legendary micing technique first brought to the forefront of
arena rock concerts by the Grateful Dead with their
ground breaking "
Wall of Sound" touring
system in which each vocal mic was two identically matched capsules mounted adjacent to each other but with their outputs connected in 'series opposing' rather than 'series aiding'. Please forgive my sketchy / hasty, lacking in detail explanation and failure to fully support my assertions with properly documented references. If you saw / heard / remembered any of their tour's stops along the way, you couldn't help but be impressed by their audacity to flaunt the rules of physics and standard operating practices by having the
gall to put themselves and their vocal mics directly IN FRONT of their towering main stacks and stand there playing, singing, and shifting your hearing
threshold WITHOUT a
trace of
feedback. You're definitely correct (as usual)
@FMEng in your post and I'm sure
@John Palmer is paying rapt attention along with joining me in thanking you for your post. I'm CERTAIN 10 seconds of Googling "Grateful Dead /
Wall of Sound" will unearth more than you ever wanted to know about the pioneering micing techniques employed on their tour. Similar canceling techniques were employed by the military for tank, field, artillery, bomber and helicopter inter-communications applications, although with greater emphasis on intelligibility than pleasingly natural fidelity.
Thanks again.
EDIT 1; Link:
https://en.wikipedia.org/wiki/Wall_of_Sound_(Grateful_Dead)
EDIT 2; Quote from link: The
Wall of Sound acted as its own
monitor system, and it was therefore assembled behind the band so the members could hear exactly what their audience was hearing. Because of this, Stanley and Alembic designed a special
microphone system to prevent
feedback. This placed matched pairs of
condenser microphones spaced 60 mm apart and run
out of phase. The vocalist sang into the top
microphone, and the lower mic picked up whatever other sound was present in the
stage environment. The signals were added together using a differential summing amp so that the sound common to both mics (the sound from the Wall) was canceled, and only the vocals were amplified.
Toodleoo!
Ron Hebbard