Wrong sound effect

Two tones, the second lower and slightly sour. This is the version most projects want, because the downward step is understood as a refusal even by someone who has never seen the interface before.

Two flat beeps at the same pitch, deliberately toneless. Reach for it when the refusal is procedural rather than personal, like a card that will not read or a door that will not open.

A muted knock with no ring in it. It reads as weight rather than error, which suits a game action that fails physically instead of a form that fails validation.

A single tone sliding from mid to low and thinning as it goes. The slide takes longer to finish than a blip, so it fits a failure the audience watches happen.

Short, abrasive and unpleasant on purpose. Use it where the mistake has a cost, and use it rarely, because a cue this rough stops being information once it repeats.

Two rounded notes falling gently, with nothing sharp in them. The polite end of the range, for a product that has to say no dozens of times a session without wearing anyone down.