Why does my Apple TV announce the volume levels?

I had a similar issue, it turned out that the person had an Apple TV and an LG TV. Listening to it, i would swear it was the Siri voice 'Samantha', but it turned out to be the LG TV that had an accessibility feature that announces the volume level. Turning that off on the LG TV resolved the issue.

• Apple TV has an on-screen visual indicator for volume that can be turned on or off (for Auto and HDMI volume control options). This may be double when the TV also does something similar. Settings﹥Remotes and Devices﹥Onscreen Volume Display﹥Show|Hide
• Any audio announcement (regarding volume) is not from Apple TV, but perhaps from the TV or audio system.

Check your TV settings. Apple TV does not provide audio cues on the volume level.