Answer:
HEARD.
Step-by-step explanation:
An action verb is the form of a verb that shows the actual doing of an act by the subject. It expresses the actual happening of a physical or mental action. They are single words that describe what a subject can d or is ding or will do.
In the sentence,
"Today I heard my favorite song twice on the radio"
the action / verb is "heard". And it also shows the actual expression of the action f the subject "I". So, the action verb in the sentence is "heard".