Assuming $0.3/audio clip and base wage of $10/hr, that equates to 33.3 audio clips/hr = 266.4 audio clips/day that are being monitored by any one 'language expert'.
However, Google does not specify how long a 'conversation' is. How many sentences make up a conversation? When is the cutoff point?
Google also says '1 in 500' conversations are monitored. That means for any one 'language expert', there are approx. 133,200 conversations/day that have a chance of being monitored.
So basically, you have a 0.2% chance that your conversation is being picked up by any particular 'language expert' per day.