The following Table shows the differences in the positions of notes in a Saptak, as obtained by North Indian Pt. Bhatkhande and South Indian Pt. Sreenivas, when they attempted to fix the positions on the string by 'hearing' the notes on the string. (Refer to table in the image below).
There have been other research workers too, and their values for 22 Shrutis have been already mentioned in Topic 6.
The lesson of this experiment was loud and clear, that the Shruti positions can never be fixed by 'hearing', because, at any given time, two musicians will have a different perception of Shrutis in their brain.
The possibility of such a difference will exist irrespective of the caliber of musicians.