Why does coffee "tink" but cocoa "tunk"?

Factual Questions
1

Whenever I’m mixing up a mug of cocoa, I notice that when the spoon hits the mug, especially the bottom, it makes a resonant “tunk” rather than the more brittle “tink” sound. I always figured it was because all the particles in the liquid somehow changed its…resonant frequency or some other combination of $5 words.

Then the other day I was fixing myself a mug of cowboy coffee (imagine a french press in your mug but without the press), and while I was stirring in some sugar and non-dairy creamer (and re-agitating the coffee grounds) I thought, “surely with so many particles chunkifying the water, this mug’s gotta ‘tunk’!” But to my surprise, I was met by the usual “tink”, as if I was merely steeping tea or something.

So what gives? What makes cocoa so special it gets to “tunk”?

MetroGnome

2

After I finish drinking hot chocolate there is always a residue/sludge at the bottom of the cup when I finish. If I were a betting man, I would put my money on this changing the spoon sound to a tunk. The absence of this sludge in coffee means that the spoon is hitting ceramic, resulting in a tink sound.

3

Cocoa, as a drink, contains a lot more suspended solids and emulsified fats than coffee - even if that’s creamy coffee with lots of grounds in it - you’re halfway to something like cake batter when you mix cocoa, and cake batter definitely doesn’t ‘tink’

I think what’s going on at a microscopic scale is that the elasticity/compressibility of the suspended particles is altering the way that sound/compression waves travel through the mixture as a whole.