rdgrimes is correct, Blu-ray audio is a normal blu-ray, just authored in a way to not need a video screen to navigate the menu. It will play when first inserted into a player. Previous/next buttons work the same as a CD, and pressing the red/green/blue/yellow buttons correspond to the stereo/surround/lossless/etc audio tracks, again so you don't need a tv to see the on-screen menu. I forget which button color maps to which audio tracks. Pressing the numbers on the remote work the same as a cd too. Mark Waldrep of AIX records is not a fan because he says he would have to delete the videos from his BDs to get the Blu-ray audio sticker, which he finds silly. He also says that if you really don't want to see the video, then press the Pure Audio(1) button, or equivalent on your remote control. I noticed that the just released Sgt Pepper's 50th anniversary BD has a really nice never before released video interview by Giles Martin, and therefore can't be a blu-ray audio BD.
(1) Oppo remote controls have a button named "Pure Audio" which simply blanks the video output but not the audio output.
U-Turn Orbit Plus turntable, Marantz SR-7009 AVR, iNuke 6000DSP, DIY LinkwitzLab speakers, MartyCube + JohnnySub, BenQ W1070, Roku stick, Plex