Quantifying the effect of materials on sound and feel

I’ll preface this by saying I’m by no means an expert in materials science or physics. However, I was curious as to whether there is a more detailed way to quantify the effect different plate/case materials have on sound and feel (at least relatively speaking).

At the simplest level, sound is the vibration of particles in the air. I did a bit of digging and found that you can determine the velocity of sound through a material based on the relationship between its stiffness (represented by Young’s modulus) and density.

I got the approximate Young’s modulus / density values from Wikipedia / Engineering Toolbox and used Wolfram Alpha to calculate the speed of sound. Here is some info on a few of our favorite plate and case materials -

Material Young’s modulus Density Speed of Sound
Polycarbonate 2-2.4 GPa 1.20-1.22 g/cm^3 1280-1414 m/s
ABS 2.28 GPa 1.06-1.08 g/cm^3 1453-1467 m/s
POM 2.5 -3.15 GPa (?) 1.41-1.42 g/cm^3 1327-1495 m/s
FR4 24 GPa 1.85 g/cm^3 3602 m/s
Aluminum 69 GPa 2.7 g/cm^3 5055 m/s
Brass 100-125 GPa 8.6 g/cm^3 3410-3812 m/s
Copper 117 GPa 8.94 g/cm^3 3617 m/s
Stainless Steel 180 GPa 8.05 g/cm^3 4729 m/s
Carbon Fiber 228 GPa (?) 2.00 g/cm^3 10677 m/s

I know we have some more qualified individuals here to discuss these sorts of things, so perhaps they can help to check my work and fill in the gaps. Not sure if this is useful or if I’m just the guy in this meme


Hehe brass go BRRRRRR

(but poly go b r r r r r )

In seriousness, I think this is pretty fascinating. I just started typing on my first poly-plate gasket-mount keeb these past few days, and wow do I love it. I wouldn’t mind being able to correlate some numbers to that.