You can now send short voice messages via instagram.
HOW IT WORKS
Go to your Direct inbox, open any conversation, a new microphone icon in the text entry box at the bottom will appear.
Tap it and hold while speaking, then release when you’re done.
The message will be sent instantly.
To dismiss the message, swipe to the right where a delete button resides.
Tap and hold to unsend a message.
It basically follows the same protocol like WhatsApp and Facebook.