This commercial was shot in Portland. The agency is Weiden & Kennedy - I have partied in their fantastic office space [Full disclosure: so have a lot of other authors, for Wordstock.]
This commerical features what is believed to be his voice.
Was a wax cylinder recording made of Walt Whitman reading one of his poems in 1890? The cylinder seems lost to history, but nearly 20 years ago a scholar in Texas found a recording made in 1951 of a radio show that featured what the host said was Whitman reading one of his poems. There’s no clue to negate the idea, and people find it compelling that the poem is an obscure one - if you were going to dummy it up or simply have an actor record a poem, it would probably be a well-known one.
You can read more about this mysterious wax cylinder here.