Give it a good blowout, into the outlet vents with compressed air can
Run Ccleaner, ADWCleaner and Malwarebytes.
Full de-fluffing would require a complete stripdown.
You can find the Maintenance Guide Manual pdf at HP Support and Downloads.
You could try getting the Sound Drivers again while you are there.
Or you may have to backup all your stuff and do a Factory Restore (+hours of updates)
Or it may be a hardware fault.