In addition to number of new additions that Whatsapp is working on, the social messaging app is also working on a new feature exclusively for iphone users that would allow them to preview the voice messages before sending. As of now, WhatsApp users can preview videos and images before they share them with their friends and family.
But there is no way to preview voice messages within the app. This new feature will perhaps allow them to determine if the voice message has been recorded correctly and if they want to send the message or not. The blog which reported the news says that the feature is still in its developmental stage and that it has not been rolled out yet.