The Audio node sends an audio to the chatbot from a local file or from a URL or from a Buffer passed by an upstream node (the simplest way to use it to chain with to File node or a Http node).

To programmatically send an audio with a Function node

msg.payload.document = '/my-file.mp3';return msg;

Or using a Buffer

msg.payload.document = new Buffer(<my-mp3-buffer>);msg.payload.filename = 'my-file.pdf';return msg;

In case the upstream node pass through a Buffer, the node tries to extract a proper file name (visible to user in the chat client) using the payload of the upstream File node or the name of the node itself.

Available parameters for the msg.payload