garbled audio - but not in headphones

Hi there,

I have rendered a few videos which work fine on various computers and phones, through earphone jacks but played through speakers the music is fine and the voice over is garbled.

I have tried

rendering out sound only in mono

updating all drivers

checking whether my hardware is MME or AISO

playing video back on various devices. for some the video plays fine on their phone, laptop whether earphones are in or out. Others its garbled when playing either way too.

I have uploaded the video to youtube or downloaded through google docs with the same result. Its always the same machines with the same results.

Here is a link to one video so you can see if it works for you

Introduction to Paramount Independent Property Services - YouTube

The laptop is new and the first video I made was fine. I have made 2 since then which have this issue with sound. I have no idea what to do next

Best Wishes

Ed