General aviation rotor craft Instructor pilot reported a near miss while in the airport traffic pattern. The Instructor performed a low pass; re-entered the pattern; then lost communications with the tower and conflicted with another aircraft; then turned away from the conflict and returned to the home airport.

Narrative

During a routine training flight into a towered airport; the student and I performed a shallow approach running landing after receiving clearance for the option and right closed on the go. After performing the maneuver; we proceeded to do the right traffic as advised and reported midfield for the downwind (as is standard protocol for the airport). After not hearing anything back from the tower (1-3 seconds)from the tower; I checked the radio frequency; and squelch; heard nothing; and then turned up the volume. As soon as the volume was turned up I heard tower stating to turn north for us and that the other aircraft had us in sight. We passed over the other aircraft who was landing on the Runway 13 that crosses the one we were cleared for Runway 17; turned north and departed home. Cause: It's hard to say why the volume was turned down as I had not done it and I didn't notice the student changing anything on the radio. The best cause I can figure out is that the volume knob is on the older side and the vibrations from our running landing possibly caused it to drop. Suggestion: Double check squelch on the aircraft in case the volume (or anything) has been inadvertently turned down or changed if radios have been silent for too long.