Conversation so far:
who sang national anthem at 2017 super bowl?
Luke Bryan sang the national anthem at the 2017 Super Bowl.
what is the vocal range of Luke Bryan?
Bryan possesses a high baritone vocal range of two octaves from A2 to A4.
how have critics described the vocals of Luke Bryan?
Commenting on Luke Bryan's vocal performance in Tailgates and Tanlines, Slant magazine's Jonathan Keefer described Bryan's voice as a pleasant, if slightly nasal, baritone.“

Question: who are the influences?
Self-contained rewrite: who are the influences of Luke Bryan?