NC - Noise Criterion Calculation
A machine
	Octave Band Center Frequency (Hz)
	63	125	250	500	1000	2000	4000	8000
NC-70	83	79	75	72	71	70	69	68
NC-65	80	75	71	68	66	64	63	62
NC-60	77	71	67	63	61	59	58	57
NC-55	74	67	62	58	56	54	53	52
NC-50	71	64	58	54	51	49	48	47
NC-45	67	60	54	49	46	44	43	42
NC-40	64	56	50	45	41	39	38	37
NC-35	60	52	45	40	36	34	33	32
NC-30	57	48	41	35	31	29	28	27
NC-25	54	44	37	31	27	24	22	21
NC-20	51	40	33	26	22	19	17	16
NC-15	47	36	29	22	17	14	12	11
0.5M	72.2	69.7	71.4	64.3	62.8	59.7	51.7	46.3
1M	73.1	69.3	72.5	63.2	61.3	58.3	51.3	45.6
1.5M	70.6	69.3	70.3	64.4	61.4	57.9	51.2	44.9
Mean value	72.09	69.44	71.5	64.0	61.9	58.7	51.41	45.64

   Use the above materials to surround A machine (2x3m) to reduce (db). How should it be calculated?

Ruukki acoustic cladding 100 mm on both sides of wall 1. Ruukki acoustic cladding 100 mm on both sides 2. Ruukki sandwich panel (SPA 150E) used as internal wall 2 For internal wall usage in both sides, sound absorption coefficients (a) for rooms are same as with single 100 mm surface. Airborne sound insulation value improvement with typical SP-wall: - +16dB