To be honest I never felt the need for one
As the others say yes at a fee
Rip off Britain is heaven compared to the German economy.
I am not sure because all of the people on my tour had our own audio devices supplied by Viking--our cruise provider. After doing a bit of online research it appears that this service is available for an extra fee--there were a lot of additional fees here!
Get quick answers from Roman-German Museum (Romisch-Germanisches Museum) staff and past visitors.