For Voice Command to work you need to have the entirety of Garmin's EU mapping installed. Do you get any error message when you try to use it? Read this to see if helps you figure out your problem with ASR: [Only registered and activated users can see links. ]. Note that some ASR related files are map-specific (i.e. they change with each map version), There are also 2 versions of the files which are device-specific (in that they may be "ASR1" or "ASR2") and i recall, without absolute certainty, that 37xx uses ASR1 and 34xx uses ASR2 so you should check the voice command files you downloaded for 37xx can in fact be used on 34xx. You also need to have in the device's on-board memory the language-specific ASR file (*.SRD) for the language you're using for voice commands, but other voice command files may be on a media card.

JCV files are also both map version-specific and device-specific however both 37xx and 34xx use the same file-type. If you have JCV files for an earlier map version than the one loaded it won't work though.