Protect your hearing. Wear earplugs when doing walkarounds. Don't fly in noisy SEP a/c as a PPL without wearing ear protection. Don't think you are invincible in this area. I used to walk around jet engines often when I was young thinking it wouldn't hurt me. Now I am paying the price with partial hearing losss and tinnitus (constant ringing). Other friends who were careless when younger suffer from this as well.