Use it as the closing beat after a small failure has already been shown, not as the opening. Pair it after the Awkward Moment sound for a small letdown, or before the SpongeBob Disappointed sound when you want that letdown to lead into a bigger reaction.
关于此声音
This is a brief Japanese voice line, lasting about two seconds, in which the speaker plainly says they are sad. The words themselves carry the whole weight, a small, honest admission rather than a dramatic outburst. It feels quietly downcast and a little weary, suited to a low moment, a gentle letdown, or a scene needing a touch of sincere melancholy.