Making a list into a piece of writing is one of the simplest ways to write, so if you haven't written in awhile, here's your chance to make it easy.
Make a list of sounds you typically hear in a day. Add that all important detail staying away from vague and general. You might find a rhythm if you put "I hear ..." in front of each item on your list. Then embellish, what can you add? Think of ways of varying the sentence before those things you hear, for instance adding, "If I listen closely ..." or "Once I heard."
Make up your own instructions around this if mine don't excite you.