Sound Alerts is an incentive for stream viewers to even use more Bits on the streamers channel. Eligible Twitch Partners and Affiliates can set a Bits amount for each Sound Alerts on the Sound Alerts dashboard. Viewers will need to use their Twitch Bits, which can be bought on Twitch, to play a Sound Alert on the streamer's stream. Streamers earned a lot more revenue after they installed Sound Alerts on their channel.
When viewers perform and confirm an action that requires Bits within the Extension, streamers will earn 80% of 1 U.S. Cent per Bit used. This means when a viewer uses 100 Bits to play a Sound Alert you will get 80 US Cents for it.
The whole Bits in extension monetization process is managed by Twitch. However, Bits earned via Sound Alerts are not reflected immediately on the streamer's Twitch channel analytics. It can take 1-2 days until the received Bits with Sound Alerts show up in the Twitch channel analytics. Also, third-party platforms like Streamlabs or Streamelements cannot track your Sound Alerts Bits revenue. If you want to track your most current earnings with Sound Alerts you should look on the Sound Alerts dashboard.
You can read more information about the Payout here.
To be able to use the Bits feature and to earn money with Sound Alerts you have to be a Twitch Affiliate or Partner