Is there an arrangement of components the takes a source of gas with oscillating pressure and outputs a steady near constant pressure stream?
This is a common problem in the field of noise control (within the larger field of engineering acoustics). Do you have access to any of the standard textbooks on engineering acoustics? You'll most likely find your answer there.
Also please note that there is a device called a noise suppressor or muffler which is commonly used to eliminate or minimize the generation and propagation of noise from a pressurized air outlet. If you search on these terms you will uncover the websites of the firms that design and sell them, and find out how to solve your problem. .
You can add a few bypass pipes with a constraint such as a fin or a stator or a positive blocking valve, spring loaded, that will intake the tip of pressure surge amplitude and deliver it muted farther down the stream.
A comparable liquid regulator would be one with a slanted ramp skimming the flow at the average volume and merging it back down stream.