Concrete:

Smooth concrete: NRC: 0.02
Rough concrete NRC: 0.05
Course concrete block: NRC: 0.35
Painted concrete block: NRC: 0.27

Steel:

NRC: 0.00925
Metal roof deck: NRC: 0.10
Perforated roof deck: NRC: .89

Glass:

Heavy duty large panes NRC: 0.38
¼" large sealed panes NRC: 0.23
Ordinary window glass NRC: 0.15
Operable windows (closed) NRC: 0.04

Sheetrock:

5/8" Gypsum Board NRC: 0.11
½" Gyp on 16" studs painted NRC: 0.05