Click the green flag and test your noise level. Scratch must be allowed to access your microphone for this to work. Also if you don't have a microphone I'm sorry and you can't do this.
This is 100% by me. I just got the idea to make this over the weekend while playing around with sensing blocks Also I've found with the TV on you are commonly on off the charts. Please also note if your noise level is 0 or bellow you will be on the off the charts reading.