ESDU 88028 complements ESDU 87019, which provides prediction methods for vibration of heat exchanger bundles. After outlining the nature of acoustic resonance, calculation methods are given for the acoustic frequency in both rectangular and cylindrical ducts. Procedures, based on a correlation of all the available acoustic data (all data on periodic wake shedding derived from measurements in the flow field were discarded because of their inapplicability), are given for the prediction of resonance. Possible damage caused by acoustic resonance is considered, and the means by which a design can be modified, before or after fabrication, are discussed. The methods apply to bundles in a rectangular cross-section duct, to shell-and-tube heat exchangers and to helical coil arrangements.