Are mics on Android phones with Android 4.3 always registering sounds? Religious question for Shabbat Hi I am Jewish and on Shabbat we are forbidden from creating even the tiniest electrical spark. I recently noticed that on my laptop the mic was always listening and I could see the little green bar register sounds when I spoke, so I turned it off during Shabbat.

I use my phone as a white noise machine with an app for that, so I am wondering if I have an HTC rezound and also a Samsung Note II, will the mic on those phones have the same thing where the mic will always be listening and registering sounds, or when I am not using a call or voice recognition feature will it be truly "Off"?
It depends on the phone, the operating system, and apps installed on it.

Older Android phones do not activate the microphone unless it is required by an app (e.g. phone, voice dictation, etc.)

Newer phones such as Google's Nexus 5 or Motorola's Moto X for example, have a dedicated low-power audio processing module that can be configured to be always on, and listen for particular trigger phrases (e.g. "Ok, Google"), even when the phone's screen is off.  There are some 3rd-party apps that mimic this functionality on phones without the dedicated sound processors, but at the expense of higher battery drain.

Generally such features can be disabled within the system or app settings.

The religious implications of using a phone are up to you and your particular sect to determine.  Such discussions are out of scope of this site.