Conclusions

Airborne Annoyance	Impact Annoyance

Our survey data illustrates that, generally, impact noises are found to be annoying more often then airborne noises. Spencer View's acoustic isolation strategies appear to mitigate airborne noises better than impact noises, as demonstrated by the number of instances of annoyance reported for each of these categories of sound source. Beyond just illuminating the fundamentally different modes of transmission of impact and airborne sound, these statistics also demonstrate the directional experience of the apartments. Those living on the upper story rarely reported hearing noises, while those living below almost universally heard impact noises such as footsteps. It is obvious that the floor assembly more satisfactorily addresses airborne noises than impact noises. We also found that people are more likely to hear, and to be annoyed by, impact sounds. Thus, the number of reported instances of impact sounds becomes a viable criterion of the tenants' perception of satisfaction with regard to acoustic comfort. Our data irrefutably illustrates a disproportionate reporting of impact noises.

Therefore, our study clearly demonstrates that the acoustic strategy used in the construction of floor assembly at the Spencer View apartments fails to create a satisfactory perception of acoustic comfort.

The results of our survey clearly present the argument that acoustically satisfying environments are not necessarily created by making a building minimally code compliant. It is our contention that the more meaningful of the two criteria is the perceived comfort of the tenants. This study clearly demonstrates that sound isolation strategies implemented in the floor construction of Spencer View Apartments do not satisfactorily reduce impact noise transmission.

Our survey data seems inconsistent with the calculated values. This difference between experiential and calculated results has a number of possible explanations. There is of course the possibility of sample error, but the return rate was fairly high, and the total number of surveys returned (71) sufficient to suggest that this is not the case. Excluding this, other possibilities could expose a general problem with the methodology of quantifying sound isolation through the floor. The first of these explanations is a challenge not so much to the calculated value itself, but more to the information from which the value was calculated. All of our calculated values are based on specifications as laid out in the construction documents. There is the distinct possibility that the specifications were either not entirely followed on site, or that the specified products and techniques were not properly implemented. Further the formulation of the IIC standard focuses solely on acoustic transmission through the floor diaphragm, ignoring the structural transmission at the wall junctions, which would greatly decrease the actual performance of the building system as a whole.

Another of the possible explanations for this incongruence between survey data and calculations is that the values stated in the code are inadequate. This would not be surprising since the laboratory studies that generated these quantitative guidelines cannot take into account their real world qualitative experience. Indeed, the fact that recommended values for STC and IIC are unchanged since the 1950's invites reassessment of these recommended values.