I'm trying to clear some confusion I have when writing in different verb tenses. I found Purdow OWL's tutorial, but the explanation is not clear to me.
Here's the example from the website: Example 2: Simple present narration with perfect and progressive elements
In this scene...
By the time Tom notices the doorbell, it has already rung three times. As usual, he has been listening to loud music on his stereo. He turns the stereo down and stands up to answer the door. An old man is standing on the steps. The man begins to speak slowly, asking for directions.
Purdue OWL explanation: In this example as in the first one, the progressive verbs has been listening and is standing indicate action underway as some other action takes place. The present perfect progressive verb has been listening suggests action that began in the time frame prior to the main narrative time frame and that is still underway as another action begins. The remaining tense relationships parallel those in the first example.
I've bolded the part that's confusing to me. The present perfect progressive action began prior to the main narrative time frame (this part I understand, it's referring to the the present tense notices) but I don't know what is that "another action" that begins while Tom has been listening. What is that "another action" that begins while Tom has been listening to loud music in his stereo? Thank you!