No sound from right speaker (laptop). Hardware or software problem?

I have an Asus Zenbook 13 laptop and I am using Ubuntu 20.04

Recently the right speaker of my laptop stopped producing sound. I am trying to work out
if this is a software issue or a hardware issue.

The speakers were working fine until I noticed on a Zoom call that the sound from one of the speakers was crackling. The next day, I was watching a Zoom seminar and I noticed that the sound quality was changing intermittently, probably from the use of both speakers or just the left. After 15 minutes, the sound quality became consistently poor. The right speaker has not produced sound since then.

If I am using headphones, then sound comes out for both ears. I have a dual-boot laptop, and I am having the same issues on Windows 10. These things suggest to me that I have a hardware issue.

On Ubuntu, I have already checked pavucontrol to ensure that the left and right speakers are balanced. When I test the right speaker only, I hear no sound. I have checked alsamixer also and everything seems fine.

It seems likely that this is a hardware issue, but how can I know this definitively before I try to repair my laptop?

Thank you