Isolating the southern knee wall in music room

The southern wall stands next to a partial poured concrete wall. The attachment point for WIC clips is 16" below  the top of the wall. At this height the two walls would be around 8" apart due to the concrete wall below. To bridge the gap I used 2x4 pieces, attached to the inner wall with 3 x 2.5" screws.

This wall was pre-built on the ground, without the studs that would connect to WIC. This allowed me to insert these studs after the wall was standing and I could line up the inner studs.