It was shown in a previous communication that the transmission through an acoustic conduit could be computed if the components of the impedance of the branch line were known. In the case of the orifice when viscosity is considered the following are the values of the two components.
Proceedings of the Iowa Academy of Science
©1925 Iowa Academy of Science, Inc.
Stewart, G. W.
"The Action of an Orifice in an Acoustic Conduit and a Means of Determing the Effect of Viscosity,"
Proceedings of the Iowa Academy of Science, 32(1), 383-384.
Available at: https://scholarworks.uni.edu/pias/vol32/iss1/89