The Acer H233H does not have a microphone built into the monitor. Thus you do not have to put tape over the microphone. It does have integrated down-ward firing speakers; the speaker jack is next to the power cord on the back of the monitor. Make sure to connect the included audio cord to the Lime Green audio (speaker) out jack on your computer. All of the jacks on the monitor point down.
If this monitor had a microphone and the blue 3.5 mm audio port, you could keep the microphone disabled simply by not connecting the cable between the monitor and the computer's microphone port.
Acer has the documentation for the H233H monitor in their support section. The direct link to the manual is http://global-download.acer.com/GDFiles/Document/User%20Manual/User%20Manual_Acer_1.0_A_A.zip?acerid=633765057605336286&Step1=MONITOR&Step2=H%20SERIES&Step3=H233H&OS=ALL&LC=en&BC=ACER&SC=PA_6
. This file has the manual in a PDF inside of a compressed folder. You'll need to open the folder to read the manual.
I hope this helps. Web cameras often have microphones. Some laptops often have an integrated web camera; thus they have a microphone mounted on the bezel of the laptop. Blocking that microphone with tape might be useful. I'd block the camera too. For USB connected web cameras, simply unplug the data cable from the computer when you aren't using the camera to disable the microphone.