crackling static sound from speakers

My iMac has suddenly been putting out an intermittent static/crackling sound. Also there's a high pitch sound too. Doesn't sound good. It continues even if the volume is turned all the way down. Also the headphone jack is not functioning. If you plug headphones in, all you hear is a bassy hum. With the multiple sounds, something serious has occurred. Obviously this is nothing hard shut downs will solve.

I might add, the sounds are a bit louder on the right side than the left?

This iMac is in a clean non smoking household and is very rarely moved around.

Just wondering if it might be a faulty audio out jack (doubt it with that high pitch sound) or what other audio related solution could it be. There's zero anything on this matter on the internet. I guess the million dollar question is, if we open it up to replace the audio jack, maybe something else needs to be done while we're in there? At this moment, the jack isn't even available at this time.

Any feedback will be greatly appreciated. I know, I know, my iMac is 8 yrs old, maybe it's getting to that time:). BTW, I see posts of people talking about a red light in the audio jack...no red light.

Thanks ahead of time,

Lori