The second meeting of the participants 

The following are the minutes of the second meeting of the participants in this Inter-Laboratory Test, which was held in Turin (Italy) the 3rd of February 1997, at the Istituto Elettrotecnico Nazionale "Galileo Ferraris" (IENGF).

Minutes of the 2nd meeting of I.L.T.

Turin - 3 February 1997

1) Opening of the meeting

The meeting opens at 9:30. The Coordinator welcomes all the representatives of the participant laboratories in ILT. The Coordinator thanks IENGF for the hospitality and for the support in the organization of this meeting.
Mr. Guglielmone gives information on the coffee-break and lunch time. He also invites the interested participants to visit the laboratories of the Institute after lunch.
The Coordinator asks those present to introduce themselves and invites them to sign the presence at the meeting in the proper form (Enclosure n°1, not attached). The list of participants who attend the meeting is given in Annex 1.
The Coordinator explains the agenda, which is approved without modifications (Enclosure n°2, not attached).

2. List of participants in this ILT

The list of the participant laboratories is checked by the representatives and no corrections are made.

3. Economic aspects of participation

(missing)

4. Purchase and delivery of the specimens

The Coordinator explains that the materials were purchased from the BPB Italia s.p.a. of Casola Valsenio (RA), which produced the plasterboards specifically for this project. All the materials came from the same stock of production. They were assembled in single boxes which were delivered to the 21 laboratories.

5. Mounting of the specimens

The Coordinator explains that the mounting of the specimens were done in different periods in order to enable the supervisor to visit each laboratory (see Enclosure 4, attached in Annex 2).
The Coordinator invites the supervisor Roberto Foddis to describe very shortly the main aspect of the specimens (see Enclosures 5, not attached) and of the mounting conditions.

5.1 Changes to the “Guidelines for the construction of the specimens”

The supervisor explains that some small modifications in the procedure of the mounting were made, due mainly to practical reasons. However his presence during the construction of the specimens in all the laboratories assured that the procedure was everywhere the same.

6.  How to consider the results of the Extra-CEE Laboratories?

The Coordinator explains that only one of the three laboratories Extra-CEE has already mounted the specimens; the others two are going to carry out the construction shortly.
All these laboratories build the specimens according to the Guidelines for the construction of the specimens but without the presence of the ILT supervisor.
It is proposed to keep separate the results of these laboratories in the calculation of the repeatability and reproducibility.

7. Presentation of the results

7.1 General situation of the measurements carried out by the laboratories
The supervisor shows the collation of the results.
All the 21 laboratories in the Community carried out the 10 series of measurements requested (5 for the first specimen and 5 for the second one), so there are no missing data.
Up to now, of the 3 laboratories Extra-CEE only the Building Research Institute of Warsaw (Poland) has carried out the measurements.
7.2 Statistical analysis of the results (ISO 140 part 2, ISO 5725)
The statistical analysis of all the data has been carried out according to ISO 5725 and to ISO 140 part 2.
The supervisor shows the tables of the spreads and of the averages of the results. The stragglers and the outliers data obtained by applying the Cochran and Dixon test are indicated.
7.3 Repeatability r
The values of repeatability for both Specimens are shown in Enclosure n.6 (not attached, see Results).
In Enclosure n.7 - Figure 1 (not attached) they are compared with the tentative values indicated in Annex A of ISO 140 part 2.
7.4 Reproducibility R
The values of reproducibility for both Specimens are shown in Enclosure n.6 (not attached).
In Enclosure n.7 - Figure 2 (not attached) they are compared with the tentative values indicated in Annex A of ISO 140 part 2.
7.5 Discussion of the results.
 The repeatability values for both specimens are very low and even better than the tentative values reported in Annex B of ISO 140 part 2.
 It is observed that these results can be explained with the automatic instrumentation used by almost all the laboratories and with the test procedure established in the new version of ISO/140 part 3.  The reproducibility values for the double wall are very high in the middle-high frequency bands (up to 12 dB) and the slope of the curve is opposite to the slope of the curve of the tentative values indicated in Annex B of ISO 140 part 2.
It is proposed that one of the possible reasons for the high reproducibility in the middle-high frequency bands may be the presence of flanking transmissions. In some cases the R values are not larger than (R’max - 15 dB) indicating that probably some flanking transmissions have occurred.
 However, some of the participants observe that the R’max values sent to the coordinator may not be adequate for this intercomparison. In some cases these values have been obtained using, for example, heavyweight walls instead of lightweight walls which are similar to the ILT specimens (see Annex A of ISO/140 part 3).
 Therefore is has been proposed that all the participants should verify the R’max values in order to see if they had been obtained using lightweight walls; if not, they should make a new measurement of R’max and the results shall be sent to the Coordinator as soon as possible.
 Some of the participants propose to investigate the possible effects that the border conditions may have on the flanking transmissions, such as the border material, the dimensions and the perimeter of the niche, the exact position of the specimen in the test opening.
The Coordinator shows a comparison between the data of two laboratories, chosen randomly, and the theoretical values calculated using the methods proposed by Robert E. Jones [J. Acoust. Soc. Am. 66(1), 1979]. As the agreement is very good it is proposed to make the same calculation on the data of all the laboratories, in order to have some useful information for the explanation of the reproducibility results.  The reproducibility values for the single wall are in good agreement with the tentative values reported in ISO 140 part 2.

8. Possible further investigations

The Coordinator invites the participant laboratories to check their R’max data and if necessary to re-measure them using lightweight walls.
He also invites the laboratories to send information on the density of the plasterboards and on the absorption coefficients of the glass wool.

9. Discussion of the Index of the Final Report

The Coordinator asks if anyone proposes any modifications on the Index of the Final Report (Enclosure n. 8, not attached). The document is approved without corrections.

10. Exploitation and dissemination of the results

The Coordinator informs that this project has been presented in the following occasions: Furthermore the TC 126 of CEN and in particular the WG1 have always been informed about the state of the ILT.
The project is also described in Internet at the following address:
HTTP://WWW.UNIFE.IT/INTER_LAB/
In what concerns the exploitation of the results, the possible vehicles may be International Conferences such as ICA, INTERNOISE, EAA, and the meetings of TC 126 of CEN and TC 43 of ISO interested in the argument of the project.

11. Any other business

Any other business was on discussion.

12. Closure of the meeting

Before closing the meeting the Coordinator thanks Dr. Guglielmone for the hospitality and for the interesting visit to the acoustic laboratories of the Institute. He thanks also all the participants for their useful collaboration.
At about 17:00 the meeting is closed.

Annex 1 - Participants to the meeting

Annex 2- Time schedule of the Inter-Laboratory Test
 
Laboratory Country Mounting 1° Test 2° Test
Tech. Gewerbemuseum - Wien Austria 28/06/1996 19/08/1996 12/09/1996
Magistrat 39 - Wien Austria 26/06/1996 27/06/1996 27/06/1996
DELTA - Århus Danemark 09/04/1996 26/04/1996 30/04/1996
DELTA - Lyngby Danemark 05/08/1996 08/08/1996 14/08/1996
CSTB - Champs sur Marne France 15/04/1996 18/04/1996 19/04/1996
IAB - Oberursel Germany 18/07/1996 15/08/1996 25/08/1996
IBMB - Braunschweig Germany 16/07/1996 16/10/1996 31/10/1996
IBP - Stuttgart Germany 25/03/1996 27/03/1996 10/04/1996
MRA NRW - Dortmund Germany 10/09/1996 11/09/1996 23/09/1996
Müller-BBM - München Germany 02/07/1996 11/07/1996 12/07/1996
PTB - Braunschweig Germany 01/04/1996 20/05/1996 21/06/1996
TUB - Budapest Hungary 02/04/1997 05/04/1997 06/05/1997
IBP - Reykjavik Iceland 09/05/1997 12/05/1997 08/05/1997
Ist. Fisica Tecnica - Padova Italy 21/10/1996 04/11/1996 07/11/1996
ICITE - Milan Italy 03/06/1996 12/06/1996 13/06/1996
IENGF - Turin Italy 28/05/1996 29/05/1996 31/05/1996
MODULO UNO - Turin Italy 10/05/1996 16/05/1996 17/05/1996
TNO - Delft Netherlands 11/07/1996 23/09/1996 04/10/1996
Univ. of Eindhoven Netherlands 09/07/1996 15/07/1996 23/07/1996
IBP - Warsaw Poland 17/06/1996 18/06/1996 21/06/1996
SP - Borås Sweden 07/08/1996 09/08/1996 14/08/1996
AIRO - Hemel Hemstead United Kingdom 24/07/1996 25/07/1996 05/08/1996
BRE - Watson United Kingdom 22/07/1996 24/07/1996 29/07/1996
British Gypsum - Leicestershire United Kingdom 01/08/1996 02/08/1996 02/08/1996

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