Can someone please tell me what 'mic check' means?

[Paper Roses]

This old timer is a little behind the times!

[taterguy]

1. Yes

[Electric Monk]

2. Tuning up the Human Microphone

http://en.wikipedia.org/wiki/Human_microphone

A human microphone, also known as the people's microphone, is a means for delivering a speech to a large group of people, wherein persons gathered around the speaker repeat what the speaker says, thus "amplifying" the voice of the speaker without the need for electrical or pneumatic amplification apparatus.

The speaker begins by saying "Mic check". When the people near the speaker respond "Mic check", the speaker knows they have the group's attention. The speaker says a short phrase, part of a speech, and then pauses. Those that can hear what the speaker has said repeat the phrase in unison, and when finished, the speaker says another phrase, then pauses again waiting for a response, etc. until the speaker's speech is complete.

[Phentex]

3. DU has a good thead about it...

you aren't alone!

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=439&topic_id=2377263&mesg_id=2377379

[PassingFair]

4. Sibilance, sibilance, sibilance...

[frogmarch]

5. "Testing 123" is what

I take it to mean - just a way to let the audience know you're testing the mic to make sure it's working right.