Experimental Study on the Sound Absorption Properties of Finger Millet Straw, Darbha, and Ripe Bulrush Fibers

Table 3

NRC for different fiber combinations.

Sample code	Fibers	Sample thickness	NRC
S1	Finger millet straw fiber (F)	50 mm	0.78
S2	Darbha fiber (D)	50 mm	0.86
S3	Ripe bulrush fiber (R)	50 mm	0.84
S4	Finger millet straw fiber/ripe bulrush fiber (F/R)	25 + 25 = 50 mm	0.86
S5	Ripe bulrush fiber/finger millet straw fiber (R/F)	25 + 25 = 50 mm	0.865
S6	Finger millet straw fiber/darbha fiber (F/D)	25 + 25 = 50 mm	0.89
S7	Darbha fiber/finger millet straw fiber (D/F)	25 + 25 = 50 mm	0.88
S8	Darbha fiber/ripe bulrush fiber (D/R)	25 + 25 = 50 mm	0.88
S9	Ripe bulrush fiber/darbha fiber (R/D)	25 + 25 = 50 mm	0.90
S10	Finger millet straw fiber + darbha fiber (F + D or D + F)	50 mm	0.90
S11	Finger millet straw fiber + ripe bulrush fiber (F + R or R + F))	50 mm	0.91
S12	Darbha fiber + ripe bulrush fiber (D + R or R + D)	50 mm	0.93