WhatsApp is currently working on a review tool for voice messages. WABetaInfo discovered the feature, but it isn't available for either beta testers or the public yet. But according to the info the site unearthed, it will allow you to listen to the audio message you recorded before sending it. According to WABetainfo, "this new feature (currently under development) will add a new Review button that you can easily tap to listen to the voice message." After tapping Review, you get the option of sending the message or discarding it.
At the moment, it's tricky to review audio messages, sometimes requiring you to record your audio on another app while you record it on WhatsApp to check for any issues.
Via: 9to5Mac