Community perception of noise impact is most often influenced by the amount by which a new source of sound exceeds the existing ambient sound level. Various descriptors are used to define existing ambient sound levels. For example, the Massachusetts DEP Noise Policy uses the 90th percentile sound level (LA90), while the New York State DEC Noise Policy uses the equivalent sound level (LAeq). When new transient sounds are introduced into an environment the LA90 or LAeq may not be the best, or only, metrics for defining a design goal or noise ordinance limit. In addition to the lowest existing ambient sound levels, reviewing the first percentile (LA01) sound levels may be a more appropriate way to determine community perception of new transient sounds. Sound surveys from across the country were analyzed to determine maximum-recommended community sound levels (design goals). These design goals are based on marginal increases to the ambient sound level and comparison to existing maximum sound levels (LA01); the specific margin depends on the characteristics of sound experienced at the receptor.

This study compares tapping machines from different manufacturers and age for impact insulation class (IIC) measurement accuracy. In addition to the IIC measurement accuracy, the study also compares the impact frequency and effect of different impact surfaces (steel and rubber). The tapping machines were tested in a model condo unit in accordance with impact insulation class testing standards ASTM E1007-04 and ISO 140-6. These standards clearly state the impact frequency and type of impact surface to be used (hardened steel). Previous testing standards did not specify the material type for impact surfaces and many older tapping machines included both steel and rubber feet. The results of this study will be presented to show the effect of age, impact frequency, and impact surface on the resulting IIC measurement for the tapping machines.

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The Seelos Theater at Holy Cross College has been renovated twice since starting out as a bowling alley in the main student center on campus. This most recent renovation provided an opportunity for the school and design team to update and modernize this heavily used lecture hall and cinema. The authors will show how two different loudspeaker systems and AV systems were integrated with the architectural acoustics design built for reproduced sound. The authors found that the resultant performance of the systems performed better than was expected in computer modeling. Existing mechanical system noise mitigation, integration of existing film equipment, short construction timelines, and serving the needs of different audience types will be discussed. The authors used lessons learned with this project to help with the design of spaces for future projects.