Other possible Echo Cause

[Paul]

> If you mute either the mic or the earpiece there is no echo. If you use the
> wired headset there is no echo. The level of echo is affected by both the mic
> gain and the earpiece level. Using the speakerphone gives much more echo,
> which is expected because the volume is higher and the speaker is close to
> the mic.

Thank you for confirming this.

> It's possible, but the buzz is within the voice frequency range. If we could
> characterise the buzz sufficiently it may be possible to remove it by
> applying a suitable digital filter in the CPU, but a hardware fix is
> certainly preferable.

I was thinking a software noise gate would be preferable since it
requires less computing.  Also, anyone tried sound proofing the mic
with sound insulating foam to prevent the sound from traveling through
the phone?

-- 
Paul
Email - paultsai at gmail.com

There were moments when he looked on evil simply as a mode through
which he could realize his conception of the beautiful.
Oscar Wilde - The Picture of Dorian Gray