Preparing the test site

The test site selected for the timber floor was in the Midlands and the concrete floor site was in the South of England. The linear testing took place on the concrete floor site. Written permission was requested from the home builders and a full list of site condition requirements were forwarded to the site agents. The sites were ready for test, with free access over the measurement period. Projects that were nearing completion were selected to minimise the potential adverse influence of building work inside the apartment blocks. The sites were essentially complete, with doors and windows fitted, but the rooms were without soft furnishings (carpets & curtains). Vacant possession was granted for both sites for all test days.

The timber floor GRR testing took place over three days on 27/4/09, 30/4/09 and 1/5/09 The concrete floor and additional construction GRR testing took place between 29/6/10 and 30/6/10.

6.2.3.1

The operators

All operators were fully briefed, prior to arrival on site, to ensure that a consistent, standard approach was followed prescriptively.

Completion of one full test set (all 5 operators testing one set of 6 floors each) took between 10 – 14 hours, depending on the availability of rooms and the speed of the testers. Breaks were taken through the day for lunch and refreshments.

Each operator arrived each morning and setup independently. They were instructed to test rooms promptly, as they became available during the day. Because each test took a different amount of time, rooms became available randomly during the day. This was intentional to develop a random sample for the operators in order to avoid bias in the measurement process. It was also highly efficient, allowing each operator who completed one test to take the next room available.

113 To avoid replication, where a part is measured consecutive times without changing the setup of the measurement kit, testers were instructed to test each room fully before moving on to the next, thereby ensuring that the equipment had to be removed from the test room and reset for each test. In essence replication, requiring removing and resetting the measurement equipment from the test rooms, better represents the inherent noise in the standard test process and is the way chosen to increase the number of runs in this study.

6.2.3.2

Test rooms

The basic room information for the timber GRR is in Table 6-5 for ease of reference. All the test rooms were matched pairs i.e. same size shape and volume, and all rooms stacked vertically. Room details for the five room pairs used in the concrete GRR are contained in Appendix 14.7.3. The room pairs are tabulated with their respective details and all the rooms have volumes of between 19 – 25m3.

Table 6-5: Test Room Information Summary

Test Site Source/Receiver Room

Dimensions

Source/Receiver room Volume

Timber GRR (6 Tests) 2.4m H x 3.05m W x 4.8m L 33m3 Concrete GRR (6 Tests) Varies see Room

Dimensions 14.7.3

19-25m3

114 Figure 6-3: Site layout showing typical test rooms on ground floor of flats(blue) on Midlands test site with matched pairs of rooms on 1st floor above (red).

Care was taken to select room locations to avoid noise being transmitted between operators who were testing simultaneously. Due to time constraints it was also important to ensure all test pairs could be in use simultaneously.

6.2.3.3

Measurement procedure

The field test for airborne sound insulation requires several measurements to be carried out for each test that record average sound pressure levels in the source and receiver rooms, reverberation times in the receiver rooms and background sopund pressure levels. The measurement carried out by the trained operator follows a UKAS work instruction that lists the test procedure needed to fulfil the internaltional standard and Building Regulation requirements prescriptively. The work instruction is detailed in the Appendix to this document in section 14.3 .

115

6.2.3.4

Recording the data

Each test that was conducted was noted on a site record sheet with run numbers and room details. These were collected at the end of each day and a sample test sheet is shown in Figure 6-4 with a full size sheet provided in the appendix.

Figure 6-4: Example Site Test Record Sheet - Timber Floor Site

The sound level meters were downloaded daily to a central file store, to preserve the electronic data record. No data was analysed during the survey process, so that the testing was carried out “blind” by reducing feedback to the operators and minimising the potential for bias.

On completion, each data record was exported and saved to a single spreadsheet for each operator, prior to analysis. The files were in an excel spreadsheet format suitable

Source room position run numbers

Receiver room position run numbers

Reverberation time run numbers Date, time, operator, room number

116 for importing into a proprietary statistical software package (Minitab v15) for the ANOVA.

The data manipulation and analysis are described in more detail in chapter 7 and also listed in 14.1 Appendix 1 – GRR Data .

6.3 Conclusion

This chapter has considered the practicalities of the experimental design, with reference to recommendations from Montgomery et al , the resources available and the time limitations. The proposed GRR survey plan includes numbers of operators, parts and replicates, to provide a robust data set. It is proposed that in order to improve the reliability of the data and reduce the unwanted factors the testing will take place over a short time period, nominally 2 – 3 days so, given stable weather the influence of meteorological conditions will be minimised.

In addition, by blocking room size the part to part variation will reflect that provided by the method of construction. This information augments the expected qualitative and quantitative results for the measurement system. This standardisation of room size also allows a meaningful comparison to be made between the lightweight and heavyweight floors, and possibly identifies secondary influences of the construction. In addition, the small room size replicates the worst case condition with respect to a non-diffuse field and allows a retrospective comparison with previous work of others [58].

The next chapter describes the data analysis and preliminary results, for the GRR experiments for timber and concrete floors and additional elements measured for gauge linearity.

117