Tackling tricky acoustics from the poolside
Swimming pools are notoriously tricky spaces when it comes to providing intelligible sound. G-Sound tackles the Olympic sized Aqua Sport Center.
Situated in the western Hungarian city of Gyor, the Aqua Sport Center has been described as the most modern sports centre in the country.
The building features a 50x25-metre Olympic sized swimming pool with a viewing area comprising 800 ﬁxed seats and capacity for an additional 400. Ancillary features include a 16x10-metre educational pool, two saunas and plunge pool, jacuzzi, relax room, ﬁtness rooms and changing rooms.
The venue required a sound system to provide good intelligibly in the reverberant space and local integrator G-Sound was chosen to handle the project. The company’s owner József Gricz wrote the speciﬁcations for the project, which were accepted by the pool management, and conducted an electro-acoustical simulation.
Gricz speciﬁed RCF equipment for the project and worked with the manufacturer’s Hungarian distributors Chromasound to deliver them.
He based his system design around ten RCF P4228 indoor/ outdoor, weatherproof (IP55- rated) wide-dispersion, two way loudspeakers.
Imre Makkay from Chromasound explained: “Our target was to achieve as good as possible STI from the budget in this special environment, and of course the IP rating because of the pool operation. We had to reproduce sound accurately in all areas, not only for the spectators, but the coaches and the competitors on the starting blocks.
“The budget was limited, and we need to produce high SPLs even good tonality mainly for spoken words and for jingles, spots and background music. The water recirculation and the air handling unit is always operated on 66 dB LAeq level, so the system needs to produce minimum 20 dB more on every seat.”
He continued: “There are three main grandstands around the pool. On the longitudinal side, we’ve installed four speakers, and further units installed on each end of the room. There’s a sitting and standing VIP area in one of the corners, on a gallery, with two further speakers. The speakers are hanging above the water surface, installed horizontally underneath the electrical cable trays on our custom-designed stainless steel consoles.”
Gricz added: “We’ve deﬁned distances from the seats to the speakers, mindful of the horn’s 110° x 60° dispersion angles.”
The speakers are divided into ﬁve zones, and with a dedicated DX4008 4-in/8-out digital system controller installed in the technical room, there are free I/O’s for future needs.
Each half of the pool area is served by its own ampliﬁcation rack positioned close to the speakers in order to shorten the low impedance cable runs. The system is driven by a total of ﬁve RCF IPS 3700 stereo amps, delivering up to 2 x 1500W RMS@4Ω.
The challenges faced by G-Sound and Chromasound were all the result of the many ﬂ at surfaces (glass, water, and walking areas), and with minimal acoustic treatment, the average time decay was 4.5 sec.
Makkay explained: “After the ﬁne tuning which was done by measuring and listening experiences, the Speech Transmission Index’s average was measured as STIPA 0,48 at normal conditions (all zones operating for empty grandstands), and STIPA 0,41 at worst conditions (all zones operating for empty grandstands beside the operation of building automation). This has fulﬁlled our expectations.”
RCF ampliﬁers, loudspeakers and output digital processors