Can other people hear open-ear smart glasses?
They may hear some audio, depending on the speakers, volume, distance and surrounding noise. Open-ear describes how the sound reaches the wearer; it is not a guarantee that nearby people hear nothing.
Judge privacy at the volume you will use
Assess leakage using ordinary speech at a comfortable listening level, with another person at a realistic distance. Testing only in a noisy showroom can hide sound that becomes noticeable in a quiet room. Turning the volume down until nobody hears it is not a useful result if the wearer can no longer understand it either.
A private message is a good example of why this matters. The wearer may hear it clearly while a nearby person catches only a name or number. That partial disclosure can still be relevant. Choose the output and notification detail to suit the setting rather than assuming the hardware makes every message private.