Figure 5. Amplification of sound for the tested double orifices at(a) M=0.02, (b) M=0.033, (c) M= 0.05.L=3Do

From

Experimental Assessment of Noise Generation from I.C. Engine Intake and Exhaust Systems Components

Sabry Allam

American Journal of Vehicle Design. 2015, 3(1), 6-15