How to keep albums playing at the same volume

You know how when that commercial comes on the TV, it’s so much louder it makes you jump out of your chair?  Albums also seem to be produced at different sound levels.  When I listen to a playlist off my NAS, some albums are softer than others and it has definitely made me jump when listening to my office.

Does anyone make a device that will make sound levels more uniform without screwing up anything else?

Thanks.

JD