Open the brackets. Use the Past Simple or the Past Continuous. I (listen) to loud music when the keeper (turn) it off.

Let's analyze the sentence: "I (listen) to loud music when the keeper (turn) it off." We need to use either Past Simple or Past Continuous.

The correct form is: I was listening to loud music when the keeper turned it off.

Explanation: The action of listening was in progress when another action (the keeper turning it off) interrupted it. Therefore, we use Past Continuous for 'listen' and Past Simple for 'turn'.