a1667203

command

% setterm -blength 0       # bell length to 0.0sec
% setterm -bfreq 0         # bell frequency to 0Hz
% setterm -blength 1000    # bell length t0 1.0sec
% setterm -bfreq 100       # bell frequency to 100Hz
% setterm -bfreq 20000     # bell frequency to 20KHz

note

cf.
% man setterm