The SRD language-specific 'ASR' files required for voice command operation are those obtained via WebUpdater/GarminExpress [offered along with software version updates, Voices, Vehicles etc], and they should not be confused with the ASR & SRX files which are map-specific and downloadable with the unit's OEM map update along with other associated map-specific files such as JCV.

Have a look at x-trail's post which explains it nicely, here: [Only registered and activated users can see links. ] Post #13.