I apologize for any confusion, but there is no widely recognized or well-known "triple-slit experiment" in the field of quantum mechanics. The double-slit experiment is the most commonly referenced experiment to demonstrate the wave-particle duality and the observer effect.
I would not be aware of it.
If there are specific details or context you can provide about a triple-slit experiment, I would be happy to discuss it further or provide information based on the existing understanding .