Look at the green dots. These represent readings for people without the treatment.TFI is a poor indicator but I suppose it's a variable and they have used it in this graph to show the relationship.
There are many more green dots on the left of the vertical line than the right. This means that TFI is improving. But there are about the same number of green dots below and above the horizontal line, meaning that loudness is not changing.
I think that's encouraging because it is showing that the loudness measure is an objective measure (doesn't change during the control phase), and TFI is not (does change during the control phase, something we might expect from a self-assessment questionnaire).