One of the items that entered my mind are possibly cultural differences. Not exactly sure what they are - if there are any - between Tasmania and the US (or Canada). Our laws wouldn't be relevant, not that anyone has a law or "right" to listen to anything in the workplace, and the continuum of managers spans from transformational to narcissistic (managers are like things floating in a swimming pool... sometimes it's a Baby Ruth bar, sometimes it's some other kind of floatie).
If you were wearing ear buds or headphones, how would anyone know what you were listening to, to begin with? That kind of loses me. What was the initiator to all this?
For what it's worth, my work environment is usually completely silent. There are some hushed conversations in the background from time to time. The phones used to ring, but things have been slow, and they don't ring nearly as often as 5 years ago. People typically don't chit-chat, and a few people do have ear buds plugged into their smartphones or computers. Don't know/don't care what they listen to, although by the expressions on most faces all day, it appears to be John Jacob Jingleheimer Schmidt on a never-ending loop. I tend to have Broadcastify on listening to my hometown. Or, I have the scanner on listening to my current city's police, fire, and EMS (or sometimes just police). Right now, I've got the control tower to the local airport - not with headphones or ear buds, but just loud enough to overcome my tinnitus. I spent decades at work with the (public safety) radio on in the background hearing what's happening in my world and silence, to me, is mind-numbing. I find that, as a hobby, over the past 14 years here in the US, I've become more self-conscious while listening, and it's almost like I feel I have to conceal it.