This isn't what you are looking for but... for my community I made a blank hintbox... Just follow the steps below and no more annoying sound!
Hint Box Sound Removal.
To disable to hint boxes swoosh sound I made a blank sound file and its really easy to install. Just unzip the zip file and then put the sound folder in your /steam/steamapps/username/counter-strike source/cstrike/ folder and you won't get the sound anymore. Enjoy!
Zip File Is Here.
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