A linearity test for acoustic one-port sources

Linearity Tests for in-Duct Acoustic One-Port Sources

“…Equation (3) gives the linearity coe$cient suggested in reference [3]. An impedance measurement can be regarded as a single input/single output problem, where q( f ) is the input, p( f ) is the output and Z( f ) is the linear system which is to be determined.…”

“…It is therefore useful in the experimental situation to have methods to determine whether a linear model can be used. Such a linearity test has been suggested for the methods with an external source in reference [3]. In this paper, general linearity tests for all measurement methods are presented.…”

“…Since there are two unknowns two measurements should be su$cient, which leads to the two-load method [4]. If more than two loads are used an overdetermined problem is obtained, which can be useful for improving the measurement results [3,6,9], and for checking if the source behaves as a linear system [3]. The two-load method requires that it is possible to make complex pressure measurements, which means that a reference signal related to the sound generating mechanism of the source is needed.…”

“…First, the source impedance is determined by exciting the source with the sound "eld from an external source and using, for example, the two-microphone method [2,3]. In the second step, the external source is turned o!…”

“…A review of di!erent measurement methods for determining the source data can be found in references [1]. The measurement methods used to determine the source data of acoustic one-ports can be divided into methods &&with an external source'' or direct methods [2,3] and &&without an external source'' or indirect methods [4}8].…”