Cover both sides of the wood shingle with a thin layer of carpenter's glue, and insert the narrow end of the wood shingle into the opening between the joist and the subfloor.
Tap the flat end of the wood shingle to force it between the joist and the subfloor. A wedged wood shingle closes the space between the subfloor and the joist to eliminate the squeaks.
Jiggle the wood shingle to test its looseness, and hammer the shingle until it is firmly wedged into the joist. Do not continue to hammer the shingle once it is firmly in place, as you can create a larger gap between the subfloor and the joist.
Sweep the floor using a broom to remove dirt and debris from the floor surface.
Sprinkle baby powder into the cracks located between the hardwood floor's panels. Alternatively, squeeze wood glue between the floor panels and wait for the glue to dry.
Wipe up excess baby powder or wood glue to finish sealing the floor.