Are your books available in audio?
The MacLeod trilogy, The Campbell trilogy, and the twelve novels of the Highland Guard series have all been released in audio by Recorded Books and Tantor Audio. Look for them at your favorite audio bookstore or on Audible.
There are no plans at this time to have audio versions of the two Regency set novels (The Unthinkable and Taming the Rake) or the two novellas (The Knight and The Rogue)