Go to the Acer laptop to the tab "Sound". For this in control panel in the right corner click the icon to configure the sound (most drawn by a speaker). The screen will open a dialog box with multiple tabs. If the icon in the control panel there, click the "start" button. Select "settings" and then "control Panel". In the opened window, other settings, search for "Sound equipment". This module can have a different name depends on the operating system of your laptop.
Go to the tab "Recording" - it is responsible for the built-in microphone. If it is, you will see the appropriate icon. Click on it or click Properties.
In the opened settings window, the microphone check that all parameters have been correctly included. In the "General" tab verify that "Use of devices" contain the parameter "enable". Go to "Levels" and move the sliders in the "Microphone" and "microphone boost" to max. Click "Apply" and test the microphone.
To test the microphone you can use the standard Windows utility "Recorder" in the menu "start". Press record, say it, save and try to reproduce. In case of failure, try to set "Exclusive mode", which is responsible for the loudness of sound transmission. To do this, navigate to the sound settings and in the Advanced tab put a tick in the presented points. Test the microphone again.
If again no result, try updating the controller driver. This can be done in the same sound settings in the "General" tab, click the Properties button next to "Controller".