> you have to substract a 10db echo to recover a 1db voice You would think so, but subtracting the (speaker-generated, i.e., known-signal!) sound from 1cm away

> you have to substract a 10db echo to recover a 1db voice You would think so, but subtracting the (speaker-generated, i.e., known-signal!) sound from 1cm away is trivial. The hard part is subtracting the echoes off your walls, laptop, desk decorations, etc. etc. etc. That's not 10db, but it's still on par with your voice! You are not wrong at a high level -- speakerphones are terrible -- but it's not because the speaker is right next to the mic!