When someone sends me a sound message, I try to listen to it but all I get is the notification sound the whole way through and I can’t hear the message. Also I don’t always get the notification beep when someone sends me a normal WhatsApp message or photo. Hope this makes sense.
Tap the “contact” heading at the top of the message and check if that particular contact notification has been put on mute. I mute certain groups, which have a lot of chatter, as the constant pinging drives me mad.