Besides the main flash modes listed above, the Nikon D3200's onboard speedlight can also be used in manual mode, in which you can set its power output to fixed levels of full, 1/2, 1/4 ...

The Nikon D3200 user manual says it's effective at all ISOs ... so you can see that the "Off" setting still applies some noise reduction. See for yourself how the two noise reduction settings ...