Perforated baffle, typically a straight pipe with a lot of small holes. Usually being use in exhaust muffler that people called as the lowest air flow restrictions “silencer” or “core”.
It’s classical design that allowing the radiating sound energy to pass through the holes to the packing where it is absorbed and damped.
This type of “core” can usually be found in Max Racing Exhaust Straight Flow Series Glasspack resonators , Mufflers & Center Mufflers in Round , Oval , Special T box type & h-box muffler.
