Living with helicopter noise – evaluating sound insulation techniques for domestic dwellings using real helicopters

Abstract

Specific remedial works designed to improve sound installation and reduce the noise level produced by helicopters inside dwellings are described. The theoretical problems and practical solutions to installing high-performance acoustic insulation to a traditional property in the United Kingdom are presented. A novel application of ISO 140-5 is presented using real helicopters to measure sound insulation in situ in the presence of multiple flanking transmission paths. Dedicated field trials to evaluate the performance of such acoustic double-glazing and associated modifications systems were performed and the precautions taken to minimise measurement uncertainties over the extended time period of the trials are detailed. The field trials involved the use of military training helicopters following selected flight paths around the property, while noise-level measurements were made internally and externally, before and after replacement of the existing single-glazed windows and attenuated ventilation units were installed. The results show that after replacing the main windows with acoustic insulated glazing units, sound insulation levels of 40 dB or above are achieved in most rooms. The results also illustrate the importance of effectively addressing ventilation when windows are replaced. It is concluded that despite complications due to sound flanking and regulatory ventilation, the use of acoustic double-glazing units and properly attenuated ventilation units can effectively reduce helicopter noise in suitable dwellings. Practical application: This article provides an evaluation of ways in which the sound insulation of dwellings can be practically improved to reduce the impact on everyday living of noise from helicopter operations. It addresses concerns about the practical use of high-performance acoustic insulated glazing units (IGUs) used in combination with acoustic through-the-wall ventilation. It also addresses the existence of multiple flanking sound paths. Sound insulation data from a field trial involving a conventional brick-built house obtained before modification is compared in a controlled manner with that obtained after fitting acoustic IGUs and after introducing ventilation to comply with current Building Regulations.