This 40% resistance is extremely helpful and is taken over poison resistance as Bloat's poison attacks can be easily avoided if you take them out fast enough. As the berserker, getting sonic resistance is helpful as you have to go face on to take out the siren.
Sonic Resistance is the preferred perk because siren's screams cannot be avoided, and its AOE damage poses a huge threat to the entire team, so sirens are priority targets and should be taken out ASAP. It is important to learn the proper skills to parry a scrake and fleshpound with your weapons. The Berserker has a high damage output and is one of the few classes tasked with taking out the large zeds (Scrakes and Fleshpounds). This makes sense as you are fighting zeds face to face. It has damage resistance and a higher healthpool as compared to other perks. The Berserker is a melee class, close combat fighter that stands on the frontline and acts as the meatshield of the team.
Welcome to the Killing Floor 2 Berserker Guide.