The AXYS^® Asymmetric Boundary Flare (ABF) has been specially developed for use in road traffic tunnels to form part of the voice alarm and announcement systems. The technology involved has been patented.

The ABF geometry (essentially, half of a horn) is based on the principle of acoustical mirroring, in effect the mirroring creates the other half of the horn. The ABF is mounted on the ceiling which acts as a waveguide; reducing lateral reflections and obtaining a coherent wave front.

Installations include:
• The Benelux tunnel, Rotterdam, The Netherlands
• The Markusberg tunnel, Luxemburg
• The Kil tunnel, near Rotterdam, The Netherlands
• The Sijtwende, The Hague, The Netherlands
• The IJ Tram tunnel, Amsterdam, The Netherlands
• The Baldock Tunnel, Baldock, United Kingdom
• The Blackwall Tunnel, London, United Kingdom
• The Rotherhithe Tunnel, London, United Kingdom

Related Links:
::: AXYS^® ABF-260 Brochure :::
::: Datasheet download page :::
::: Recommended Amplifier :::

The advantages of the ABF approach include:
• Superior Speech Intelligibility
• Minimum number of sources due to long throw
• High Directivity
• High Power
• Low Distortion
• Large front-to-back ratio
• Superior sound quality to conventional folded horns, the ABF has a useful frequency response up to 8 kHz
• Reduced installation and maintenance costs compared to conventional folded horns