No step sound when walking on Anvils

Note: I am not sure if this is intended, but it doesn't make any sense to me.

What I expected to happen was:
When sprinting over a line of Anvils, I expected a sprinting sound, as if sprinting over stone.

What happened was:
Sprinting over them (regardless their damage state) will not create a sprinting sound, neither on survival nor creative.

Steps to reproduce:
Build a line of anvils on ground level and add a line of grass, stone etc to compare.