Mr Woody is correct.
APU, Aircon packs, brake fans etc... all emit harmful noise. You do not necessarily even hear the frequencies that do some of the most insidious damage To your hearing.
The issue that needs to be addressed is the root cause of these incidents. For starters situational awareness is very poorly displayed by many ramp staff. Complacency is often the culprit. Terms like, normalization of deviance or predictable surprise are linked to lack of care, be it from no training or no idea.
Walking the ramp during preflight should not it be riddled with more hazards created by muppets driving like lunatics. It is as though we need eyes in the back of our heads AND super ears that are impervious to the noise pollution....