I am going to add this to our Frequently Asked Questions topic.
When posting in the forum and referencing a previous post is it very important to provide a link to that post so the rest of our viewers are able to get the full context.
In that previous post I stated that custom sounds were available for Study Alerts and Price Alerts. I omitted Chart Study alerts because custom sounds are not currently supported for Chart Study alerts in Thinkorswim.
I submitted a feature request to TDA support some time ago but they have not responded. If everyone who reads this post takes the time to submit a feature request we have a good chance of getting this added to a future release of Thinkorswim.
Two screenshots below show how to submit a feature request to TDA support.