Unable to hear voice notes

Hey everyone. I'm posting here on behalf of my friend who is having an issue with her Whatsapp. When she tries to listen to voice notes she is unable to get any volume to actually hear them; the microphone icon with a cross through pops up on the screen and she is unable to do anything to sort it. I've included a screenshot of what she sees when she tries to play it. And the message does play in the sense that the little blue ball (must be a better way to describe that lol) runs the whole way along the bar

I've looked around for advice and she has tried the following with no success

- She has tried restarting the phone
- She has made sure she has latest Whatsapp updates
- She has tried listening to it like a phone call with the phone up to her ear to activate the other speaker

So none of these have worked and I've been unable to find a similar problem while looking around and am just hoping against hope that someone on her can be of assistance

Oh and its an iPhone 7 she thinks if that matters

https://imgur.com/PH3xpkd