PROCEEDINGS of the23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

Acoustic adjustment of large Sports Halls. Case study: correctionof the acoustic response of an Ice Arena for uses other thanskating.
Alberto PIFFER1; Elena RESENTERRA2
1
2

Freelance, Trento, Italy

Freelance, Belluno, Italy

ABSTRACTIn 2016, the municipality of Folgaria - North Italy - decided to using its ice arena for various activities dueto the difficulty in the economic management of a structure exclusively dedicated to ice skating.
This is a structure with a playing field of 2,500 m2 and 1,000 m2 for the grandstand. The roof has two flaps
with a variable radius curved course and a maximum height of 19 meters. The total volume, equal to 53,000m3, was initially characterized by a reverberation time of about 8 seconds at the middle frequencies.
The author has been commissioned for the feasibility study aimed at verifying possibilities for intervention.
The second step involved the detailed design of the interventions and their cost for the preparation of thecompetitive tender. At the beginning of 2018 the building process were contracted and the works, of which
the author was the Construction Supervisor, were completed in November. The reverberation time is now
equal to 2.2 seconds and allows the use of the environment for concerts, meetings, parties and sporting eventsof various kinds.
This contribution reports the whole history of the project, going from the construction phases until the final
approval tests.
Keywords: Ice arena, Reverberation time, Interventions.

1. INTRODUCTION
In 2016 the town of Folgaria in Trento (Italy), given the difficulty in the economic management ofa structure dedicated to ice skating only, decided to evaluate the possibility of its use for different
activities.
It is a structure with a play area of 2.500 m2 and 1.000 m2 dedicated to the stands. The roof, madeof a wooden structure, has two curved flaps with variable radius and a maximum height of 19 meters.
The total volume, equal to 53.000 m3 , was characterized by a reverberation time at the central
frequencies of about 8 seconds. The preliminary study was aimed at verifying the feasibility of thework and propose solutions. The executive design of the interventions and the economic quantificationof the works for the preparation of the call for tenders continued. At the beginning of 2018 the works
were contracted out and the intervention was completed in November.
The reverberation time is now equal to 2.2 seconds, in line with the forecast data.

2. BACKGROUND
The ice arena of Folgaria is a structure built in different phases, initially there was only an outdoor
plate, used for skating and events of various kinds. The ice rink has been covered and finally theadministration has provided to close the perimeter of the structure. Following completion, thedifficulty of managing the space for musical or "spoken" events identified significantly due to thehigh internal reverberation.
124598alberto.piffer@gmail.com
elena.resenterra@gmail.com

Figure 1 – Plant and section of the ice arena.
In Folgaria there is no tradition related to ice hockey or competitive skating. The administration
has identified the need to use the structure for activities other than skating at the amateur level. These
activities could include concerts, conferences, parties and other sporting activities not related to theworld of ice. Initial checks showed an average reverberation time of 6.2 seconds from 125 to 4000
Hz, with positions where 9 seconds were exceeded at 500 Hz.
P1_01 (RT20) - RT60 1/3 P2_01 (RT20) - RT60 1/3 8s7Seconds

65432
1063

Hz 125

250

500

1K2K

4K

8K

Figure 2 – Reverberation time for two source positions.

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3. PLANNING OF INTERVENTIONS
The objective of the adaptation project was determined by the need to guarantee ideal conditions
for the diffusion of music and speech with respect to the "stadium" configuration, in whichreverberation plays an important role in creating an involving climate for sports fans. For this reason,
the minimum objective was set at 3 seconds, with the will to go below 2.5 seconds.
The intervention points concerned:- Creation of a sound-absorbing ceiling covering the board partially damaged by the humidity towhich it was exposed before the complete closure;- Realization of partial sound-absorbing coatings on vertical surfaces.
The project hypotheses were simulated using the ray tracing software Ramsete. The impulse
responses generated by the model were then used to auralize the audio tracks to show the client theeffect of the various intervention steps proposed.
Following the definition of the areas of intervention and the budget available, we started the phaseof executive design and economic calculation for the next tender of the works.

Figure 3 – View of the 3D model.

Figure 4 – View of the 3D model.

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4. SUPERVISION OF WORKS
The works, which began in June and then suspended in the summer to allow sports events alreadyplanned, were completed in the autumn. In total, the following materials were installed in 60 working
days:
Table 1 – Summary of the materials used and their location
Position

MaterialQuantity

Roofing

Glass fiber panels

3814 m2

Upper area tribunes

Perforated plasterboard slabs

238 m2

Side wall and bottom area oftribunes

Perforated metal panels

376 m2

Aeration system unit

Suspended elements – Baffles
Dimensions 200x100x20 cm

26 pcsSide walls

Aesthetics glass fiber panels
Dimensions 120x60

84 pcsFigure 5 – Installation of the ceiling. Design and execution of the project.

Figure 6 – Realization of the acoustic ceiling. Installation of the grid and glass fiber panels.

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Figures 7 – Installation of perforated metal panels on the side walls and under the grandstands.

Figures 8 – Installation of polyester baffels inside the aeration system unit.

Figure 9 – Installation of aesthetics glass fiber panels.

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Seconds

During the construction phases, various impulse response measurements were performed to verify
the variation with respect to the quantities of material installed.
8s
7.5
7
6.5
6
5.5
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
063

Hz

125

Start condition

2506%

50036%

1K

47%

2K

87%

4K

Final condition

Figure 10 – T20 depending on the progress of works.

5. FINAL TESTSAt the end of the work, completed in November 2018, the verification of the impulse response wasrepeated, comparing the results obtained with the initial situation and with the forecast data of thecalculation model:

Figure 11 – Comparison of results (T20) ante/post operam and estimated.

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Table 2 – Pre / post operam comparison of some quality indicators.
Parameter

Measured values

Suggested values

Ante

PostSpeechMusicT20 [s]

6.20

2.23

1.2 ÷ 1.8

1.9 ÷ 2.5

C50 [dB]-10.87-2.83>2-

C80 [dB]-8.78-1.17-

D50 [%]

9.55

34.65

≥ 50

≤ 50

Ts [ms]526

143< 5050 ÷ 250

BR

0.93

0.99

-1 ÷ 1.25

STI

0.36

0.67

> 0.45--4Figure 12– View of the inside of the ice arena before/after works.

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+2

6. CONCLUSIONThe intervention has fully achieved the expected results. During the first events organized in thewinter season 2018/2019 it was already possible to appreciate the considerable improvement in theintelligibility of speech and the clarity of music. From an economic point of view, the final amount ofwork was 5.7% lower than the cost of the project, with a cost of € 85 per square meter of material
installed.
The acoustic characteristics obtained now make the ice arena of Folgaria a suitable place also forthe organization of musical events. Thanks to the possibility of greater use of this space, the municipal
administration will be able to amortize the investment made in an estimated period of time of 5 - 8years.

Figure 13 – The ice arena after the end of the works.

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