An example system includes a microphone sensor for an electronic device and a chamber coupled to the microphone sensor. The chamber is to be selectively filled with a fluid or having a vacuum therein. When the chamber is filled with the fluid, sound waves are allowed to travel through the chamber to the microphone sensor, and fluid pressure in the chamber causes an indicator to be in a first position. When the chamber has a vacuum therein, sound waves are prevented from traveling through the chamber to the microphone sensor and the vacuum in the chamber causes the indicator to be in a second position different from the first position.