Start processing audio input. This enables the use of other AudioIn methods like getLevel(). Note that by default, AudioIn is not connected to p5.sound's output. So you won't hear anything unless you use the connect() method.
Certain browsers limit access to the user's microphone. For example, Chrome only allows access from localhost and over https. For this reason, you may want to include an errorCallback—a function that is called in case the browser won't provide mic access.
Syntax
start([successCallback], [errorCallback])
Parameters
Name of a function to call on success.
Name of a function to call if there was an error. For example, some browsers do not support getUserMedia.