[MCBear]

Per the NFHS VB Rules Book:

Rule❒4 Player Equipment and Uniform
The NFHS does not perform scientific tests on any specific items of equipment to determine if the equipment poses undue risks to student-athletes, coaches, officials or spectators. Such determinations are the responsibility of equipment manufacturers.
NOTES:
1. Prior to the match, head coaches shall verify that all their players are legal and wearing legal uniforms and equipment.
2. Each state association may, in keeping with applicable laws, authorize exceptions to NFHS playing rules to provide reasonable accommodations to individual participants with disabilities and/or special needs, as well as those individuals with unique and extenuating circumstances. The accommodations should not fundamentally alter the sport, allow an otherwise illegal piece of equipment, create risk to the athlete/others or place opponents at a disadvantage.

Following that, per 4-1-4:

ART. 4 . . . Any equipment that in the judgment of the first referee increases a player’s advantage or presents a safety concern, i.e., towel tucked in uniform waistband, is prohibited.

You (or PIAA) will have to determine if the hearing aids present a safety concern or not. If PIAA does not make a determination, then we have to fall back on Rule 13: Common Sense.