Sound transmission losses across coupled compact resonators along an infinite rectangular duct and the noise reduction bandwidths

The effects of coupling compact resonators on the sound transmission along an infinite rectangular duct and the underlying wave interactions are examined in detail in the present investigation both experimentally and numerically. The noise reduction bandwidths are also studied. A simplified modal analysis is also carried out to provide brief theoretical support to the observed shift in sound transmission loss peak frequencies due to resonator interactions. Results indicate that coupling resonators has the potential to widen significantly the continuous noise reduction bandwidth provided that the standalone sound transmission loss peak frequency of one of the resonators is not less than 90% of that of another resonator in the assembly. This finding applies to dual, triple and quadrupole resonator assemblies. The present study also proposes an indicative simplified model for predicting the peak sound transmission loss frequencies of dual-resonator assemblies.