I had a loud creaking noise that occurred whenever anyone walked near a partition wall between two bedrooms, on either side of it. Silent Floor Solutions (SFS) investigated, and we set a date for the work to be done (injection of material under the floorboards).
But then SFS encountered a similar problem elsewhere, and realized that their usual technology was not going to be effective in solving the problem. They came to the conclusion that there could be a structural problem inside the wall, not simply a gap between sub-floor and joists (the usual culprit).
Rather than abandon the project, or proceed with an ineffective treatment, SFS brought a renovation contractor to my house, who expertly removed the baseboard and opened up the base of the wall. He discovered that the builders had screwed the metal studs to the bottom metal plate only on one side. It meant that any slight deflection of the floor caused movement between the bottom plate and the studs. He added three screws and some construction glue, secured the drywall better, and restored the baseboard. Creaking gone!
Even though this correction did not use the technique normally used by Silent Floor Solutions, I'm impressed with the resourcefulness and commitment they showed to get my problem solved. I would definitely recommend this company. They're experienced enough to realize that every case has its unique aspects, and honest enough to seek the right solution rather than the easy route.