Strange sound produced by Android Emulator when turned on in Android Studio

That sound was actually the notification sound of the emulator. Since my app is in landscape mode, it needed me to configure the keyboard in landscape mode. So the notification came out.

Try using emulators, like genymotion or bluestacks. They are pretty good. On the other side, in my experience, Android Studio emulators are very slow and buggy.

Turn off Touch Sounds on the Android device/emulator.

You can find it under Settings -> Sound & notification -> Other sounds -> Touch sounds