Some of us played noisy sessions before electronic tuners were commonplace (I hesitate to say “unavailable” as they’ve been around for decades but beyond the reach of most/many musicians).

As it happens, I do often “cheat” with one of them but, a couple of sessions ago, my go-to tuner was in an instrument case I’d left at home and, at the following session, I remembered it but the battery was flat. I simply tuned by ear to fit in with everyone else - no problem.