The most common reason is that music is muted or at zero volume on your side, or the room simply has no station playing. Work through the checks below in order; most players are fixed by step 2 or step 4.
1. Is a station actually playing?
Open the room's info panel and look at the radio control. If it says Radio Off, no station is set, so there is nothing to hear. If the control looks dimmed but shows a station name, music is muted on your device (see step 2). Only the room owner (or, in a Crew Room, a Crew Leader) can set a station. In Worlds, the creator decides whether there is a radio.
2. Is music muted for you?
A station can be playing for everyone else while music is muted on your device.
Tap the radio control in the room's info panel. For visitors, this switches the music back on if you muted it. If you manage the radio, make sure Mute for me is off on the Radio Stations screen.
Open Sound Settings and raise Music Volume above zero.
Muting through any of these sets your Music Volume to zero everywhere in Highrise, so one tap in a past room can keep every room silent.
3. Is your device volume and silent mode okay?
Turn up your device's media volume, switch off silent or ring-off mode, and disconnect any Bluetooth headphones you aren't using. On a computer, check the system output device.
4. Does leaving and rejoining the room help?
Some stations only start playing after you re-enter the room, and a stream that drops and reconnects can stay silent until you rejoin. Leave the room, wait a few seconds, and join again.
5. Is someone talking on Voice?
When someone speaks on Voice, the music is turned down so you can hear them. It comes back up when they stop.
6. Is the station itself down?
Internet radio stations go offline sometimes. If you see "There was a problem with radio station playback", the station isn't reachable right now. Ask the owner to pick another station. Room owners can test this by previewing stations from the station list.
7. Is Highrise up to date?
Install the latest version of Highrise from your app store, then fully close and reopen the app.
Still silent?
If music is silent in every room even with volume up and an active station, contact Support through How do I contact support? and include:
Your device model and app version
The room name and the station name shown in the room
Whether other players in the same room can hear it