I am using `@opentok/client` to build an Angular6 app for a simple multiuser video chat.

I want to do a 'spotlight' (eg. fullscreen the user currently speaking in the session) feature using `hark.js` for speech detection.

The problem is that this library needs the source `MediaStream` to process the audio and emit events that I would catch and process.

I would like to get the `MediaStream` from OpenTok's subscriber class, but how to do so is nowhere to be found, but since it's based on common WebRTC it should be doable.

Any leads?

Sample code :

```
 this.opentokService.initSession().then((session: OT.Session) => {
  this.session = session;
  this.session.on('streamCreated', (event) => {
    this.streams.push(event.stream); //creates the subscribers elements
    var speechEvents = hark(event.stream, {}); //raises error, how to get a proper MediaStream here?
  });

```