Comment by jloughry

That hardware capability is exploited in the following paper, if you want to know the details:

Mordechai Guri et al. (2016) 'SPEAKE(a)R: Turn Speakers to Microphones for Fun and Profit'.

http://cyber.bgu.ac.il/advanced-cyber/system/files/SPEAKE(a)...

By Mordechai Guri, Yosef Solewicz, Andrey Daidakulov, and Yuval Elovici.