Free-fall question (speculative)

[Kyriakos]

Can you think of a case (even unrealistic, but not impossible) where someone trying to establish the height to the ceiling of the (dark) building they are in by calculating when some falling object makes a sound on the distant ground below, would always form a wrong (but the same one) view about the height of the ceiling?
Let's say they had the means to calculate time, with some relative accuracy (it's only some seconds for the sound of impact) and they also knew (again with some, or even great, accuracy) the height they were now at.
Do note that:
A. the falling object has been heard a number of times, with no real variation in the time it took for it to reach the floor below.
B. nothing is visible in the building/area apart from the immediate surroundings of the observer (so he can see the object falling past him).
C. the observer is at some point relatively near the sea (ie not hovering outside of the Earth).

Ideally I would like to build a story around an ambiguity, but don't quite see an angle- maybe only someone consistently altering the speed below or above the point of observation. Even if we assume the object was thrown from massive distance, there should at the very least be a correct calculation of that distance. The observer/protagonist is using the equation for displacement on account of 1/2 gravitational acceleration(t^2). Can you?

 

[CKS]

The situation that immediately springs to mind is that the object landing is not the object your observer thinks it is. For example, water dripping regularly, and timing to the landing of the drop before or after, or dripping water landing quietly on one surface and then re-dripping onto the ground. I'm not sure how your protagonist is going to hear water droplets from far away, though. Someone on the ground hitting a pipe with a wrench at, coincidentally, the same frequency as the falling object would also work, I suppose.

A more realistic situation is that the observer sees an object go by, uses the "initial velocity is zero" equation to find the height, and is horribly wrong because the initial velocity was not zero (since it was moving when it went by your observer) but the time was from the observer to the ground. Neglecting the time for sound to travel back could also cause issues, as could running into terminal speed problems. You might not want the reason to be that your observer didn't know how to solve the problem, though.

 

[Kyriakos]

Yes, the object doesn't have zero velocity anywhere near the point of observation; it has been falling for a while. The estimation of the point where the fall started was due to knowing the time it needed to go from the point of observation to the ground (from the sound of impact) and the distance from the point of observation to the ground (because the observer hiked to the point of observation or it was simply known). The story doesn't work if the calculations show any possibility of the fall starting near the point of observation (and they don't show that anyway ). Generally the idea is that if the calculation is correct, the object should have fallen from an incredible distance above, which seems bizarre - the protagonist wants to leave by hiking up, and this puzzles him.