To cough down

to silence or put down (an objectionable speaker) by simulated coughing.

See also: Cough

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in classic literature ?
Serjeant Buzfuz rubbed his eyes very hard with a large white handkerchief, and gave an appealing look towards the jury, while the judge was visibly affected, and several of the beholders tried to cough down their emotion.