Abstract:

This paper discusses a new method used to obtain the source impedance from the four-load method. The three nonlinear algebraic equations of the four-load method were modified to give three equations of a circle. At each frequency, the intersections of these circles give the real and imaginary parts of the source impedance. A computer program was developed to calculate these intersections and extract the realistic values. A frequency range from 0 to 800 Hz was considered for a 0.2286-m (9-in.) diam pipe system with a loudspeaker as the sound source. At each frequency, the circles were scanned from 0(degrees) to 360(degrees) in intervals of 0.5(degrees) allowing small percentage errors such as 0.001, 0.005, and 0.01. The computed source impedance values were compared with those obtained from the direct method. The results agree well with the decrease in the percentage error.