On mobile
On iOS
In the conversation list:
- Select the name of the conversation where you'd like to share an audio message.
- Long press and hold the recording button
to record. - Select the play button
to preview, or the close button 
to cancel the message. - Select the checkmark button
or pull up on the recording button to send.
On Android
You cannot send an audio message at the moment on Android devices. The feature will be available again very soon.