NTi @ the Olympics

At the various venues, for the spectators and particularly the athletes themselves, the loudspeaker announcements are an important source of information. In addition to the venue itself, the sound quality in the lounges, commentary room, control room, hallways and broadcast booths is considered.

NTi Audio Olympia China teaser 670x325 1

So, from the start of construction to the completion of the project, acoustics consultants controlled every step of the process to ensure that all acoustic specifications were met and to achieve the best possible sound clarity.

The GB/T 28049 standard Code for sound reinforcement system design of auditorium, gymnasiums and stadium sets clear requirements for the speech transmission index (STIPA for PA systems) in stadiums.


With increasing reverberation time, the speech transmission index decreases. However, measuring reverberation time in a large arena is no easy task. It requires not only a highly-accurate and easy-to-use instrument, but also a powerful sound source to fill the room with the test signal. This is where the DS3 Dodecahedron Loudspeaker comes in.

NTi Audio DS3 measurement 450x300 1

The measurement results are read directly on the XL2 Acoustics Analyzer and immediately identify those areas that do not meet the requirements. With no post-processing of data, the time needed is significantly reduced.

XL2 screen RT60 Reverberation Time


The louder the ambient noise, the lower the signal-to-noise ratio, and the less intelligible announcements are – so far so good. But noise from the spectators is not the only influencing factor. The acoustician therefore evaluates the venue when it is both empty and full.

When the arena is empty, there are no noisy spectators, but there are other sources, including ventilation, air conditioning and lighting, that generate noise. This is where noise curve measurements are required (The GB/T 28049 standard specifies a maximum total sound level of NR35).

XL2 screen Noise Curves

Noise curves are very easy to measure and can be read directly from the XL2 Acoustic Analyzer, eliminating the need to cross-reference the frequency spectrum.

The difficulty comes in when the area is full. There, NTi Audio has developed a creative feature to correct for the influence of ambient noise. The acoustician first measures the speech transmission index STIPA in an empty arena, and then overlays the result with the ambient noise level recorded when there are spectators present. In this way, the speech transmission index in the presence of spectators is obtained and the contradiction between the theoretical requirements and the actual measurement is resolved. 

And more

There are many more acoustic considerations in stadiums that needs to be taking into account, the sound pressure levelsound insulation, noise pollution,… All that can be measured and analyzed thank to NTi Audio’s product ranges!

Indeed, thanks to the efforts of all those working behind the scenes and sophisticated measurement systems, we were ultimately able to enjoy many great events!

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