Crystal-clear platform announcements

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Crystal-clear platform announcements

Frankfurt Central is conducting a test of an innovative audio system from HOLOPLOT

Eight different S-Bahn lines stop on the underground tracks of Frankfurt am Main Central. Everything is timed down to the minute. Different announcements are made one after the other. All passengers need to be able to hear the information clearly amidst the hustle and bustle of commuter traffic. To ensure that they do, Deutsche Bahn and the Rhein-Main-Verkehrsverbund, the transit authority in Frankfurt, began testing an innovative audio system from HOLOPLOTin the beginning of 2019. The test was ran to the end of 2019 on S-Bahn platforms 103 and 104 (see the photo to the right). Twenty-three audio modules have been installed at 11 spots on the tunnel ceiling above the platform.

Precisely targeted soundwaves send information exactly where it needs to go

Acoustics on platforms and in stations often leave much to be desired. HOLOPLOT, a Berlin startup, has developed a solution to this problem. Its innovative audio system can aim soundwaves, much like a light beam, to specific groups of people in a space. Announcements are precisely directed to specific areas of the platform. Passengers hear only the information that is relevant to them, regardless of where they are on the platform. The system eliminates anxieties about missing connection announcements and prevents competing announcements from the other side of the platform. And that means passengers have an easier time figuring out where to go, and there is less background noise overall.

The innovative audio system can direct soundwaves, much like a light beam, to specific groups of people in a space.

Smart software for consistent sound quality

Conventional speakers distribute sound outward in all directions from a single point. The technical concept behind the HOLOPLOT system is the principle of wave field synthesis, which is used to generate virtual acoustic spaces. This makes it possible to position sound outside of the actual rendering area as needed. The sound quality and volume remains constant even over great distances. The ability to direct sound makes it possible to avoid disruptive parts of the building. This prevents reverberation, which makes announcements harder to understand. The system's intelligence comes primarily from its software, which calculates in real time how speakers need to be controlled. Each individual speaker in an audio module has its own signal and its own amplifier and power supply unit. Just a few years ago, this would have proved an impossible task for a reasonably priced computer and signal processors. Chips are now much more powerful and less expensive. The system allows up to 16 different sound fields to be created, which can be different sizes and can be filled with different content in different positions.

Successful preliminary tests in Frankfurt and Munich

HOLOPLOT participated in the DB mindbox incubator program for startups in 2016, and DB mindbox in Berlin is how the partnership with DB Station & Service came to be. Its task during the program was to test the acoustic system at stations for three months and design a way to integrate the speaker modules consistent with stations' technical and structural requirements. The HOLOPLOT system was tested at Frankfurt (Main) Central and Frankfurt (Main) Flughafen stations at the end of November 2016. Customer surveys were conducted and electroacoustic measurements were taken as part of the tests. A second preliminary test was conducted on track 1 of the underground floor of Munich Main in May and June 2017. The conditions there are comparable to the conditions at the underground tracks at Frankfurt Central, where tests are currently under way.