Imagine trying to estimate the length of a straight trumpet where sounds (pressure waves) out the end are completely deadened because

a) the flexibility in the tubing walls finally managed to kill enough energy from the high peaks of your sound waves to level it down to a single level
b) losses from the tubing allowed the peaks in your sound wave to shear backwards and downwards and your valleys to shear forwards and upwards until you level out to a steady pressure.

So, my answer would be until the effects are intentionally and by design dampened through a restriction orifice or dampener, consider these effects in activity, until a formalized acoustic analysis is performed.

As a side note, the only thing I've seen that remotely resembles this is where the Engineering Institute Guidelines for FIVs touches on AIVs from high pressure losses and tells you which fittings to look at some distance L from the disturbance. But I wouldn't be quick to draw any kind of conclusions from this info.