Don't know how to drive Soundbooth but it's supposed to have all the feature of Audition in so your job should be a sinch - if it can be done at all.

In audition I would select a portion of audio that contains jujst the noise to be removed. That can be captured as a noise profile. Using that profile you can then remove all the noise from your entire clip. It works a treat for background noises like buzzes and hums. Hiss should have it;s own filters to apply. Check your manual for details

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