Determination of Acoustic Blocked Sources in a Ventilation Duct

There has been great interest in determining blocked forces using inverse approaches. The primary advantage is that blocked forces are independent of the receiver structure. It is demonstrated that a similar approach can be used to determine acoustic blocked sources on an imaginary surface along the cross-section of a duct. This can be considered as the three-dimensional equivalent of source impedance and strength. In theory, these sources should be appropriate regardless of how the system is modified downstream of the surface that the sources lie upon so long as the upstream geometry is unchanged. The method is first validated using simulation and then via a measured example.