Nether brick slabs and walls, and red nether bricks, slabs, and walls, use stone sounds

When I go to place down a nether brick slab with a regular nether brick block, the sounds are different. The nether brick block sounds like nether brick but the nether brick slabs sound like the default slab sound or the stone sound. The red nether brick slab sound also has the stone sound and it is also included with both varieties of the walls for the nether brick and red nether brick.