When do you use heard and when do you use hear?

Answer 1

"Hear" is a present tense verb. Use it when you want to give the impression that an action seems to be happening right now:

Today I hear the sparrows singing.

"Heard" is a past tense verb. Use it to indicate that something happened some time ago:

Yesterday I heard the cardinals singing.

"Heard" is also used in the perfect and pluperfect tenses, as in the following sentences:

I hear the finches now, but I have heard them on two earlier occasions too. (Perfect)

Before I heard the finches, I had heard the thrushes. (Pluperfect)

Answer 2

"Heard" is the past tense of "hear" and is used to describe something that was listened to in the past. For example, "I heard a loud noise yesterday." "Hear" is the present tense of the verb and is used to describe the act of listening to something in the present moment. For example, "I can hear music playing in the background."