Have you chosen a method to measure the sound pressure level (decibels)?? In general the SPL is not as easy as just measuring the output of the amplified output of the mic, many methods require the analysis to be done in the frequency domain and Arduino may be over tasked depending upon the rate that you want the measurements made.
I would be interested in implementing a method for measuring the SPL and the force (load) sensor, if you have researched and determined the best way to measure the SPL for your application. I want you to choose the method for two reasons; 1) I am not an acoustics engineer and 2) your concern about repeatability concerns me as it may be hard to deliver if the method does not match the environment enough. I would also require you to quantify what the repeatability requirements are, by doing this we both have the same threshold for completion and this is important for both parties to be happy at conclusion of the project.
Send me a PM if you want to discuss this offline and I will give you my direct contact information.
It may sound like I am being a PITA I just want you to understand what I need to complete the project satisfactorily,