One of the oldest loudspeaker companies in the world, with a reputation for high quality horn technology that dates back to the pre-war era, Tannoy's latest THL-1 tunnel speaker – first launched at ISE 2015 – is designed to take the company's horn heritage into a whole new area of application.
With THL-1, Tannoy aims to provide a robust, durable and cost-effective solution for Emergency Voice Alarm/Communication (EVAC) systems in the "physically and acoustically hostile" environment of road tunnels. In an application notorious for high ambient noise levels and excessive reverberation, the THL-1 transmits crisp, controlled and intelligible voice announcements throughout the space from a minimum number of loudspeaker locations, according to the manufacturer. The THL-1 is also built to withstand the corrosive atmospheric contaminants, high moisture levels and temperature extremes typically encountered in these settings.
Voice alarm systems in lengthy tunnel applications demand very high levels with low distortion to overcome both the surrounding ambient noise and the sound isolation of the vehicles, while maintaining high speech intelligibility, with an average rated SPL output of 135db. To project an effective voice alarm notice over distances of up to 50 metres, the THL-1 incorporates an asymmetrical AFEX (Architectural Flare Extension) horn, built to leverage the acoustical properties of the tunnel wall to effectively extend the waveguide effect for greater directivity and increased propagation along the horn axis. Tannoy claims the THL-1 carries intelligible voice notifications over greater distances, meaning fewer loudspeakers are required, resulting in significant cost savings.
The THL-1 was created to withstand the rigors of long-term exposure to harsh environments, and also to function reliably even in proximity to catastrophic fire and explosive events. Cable entry to the driver/transformer housing is tightly sealed by rubber grommets, and an AirNet backing behind the stainless steel grille prevents moisture ingress to the horn. The AFEX horn is constructed from thick, fire-retardant, multi-layer fiberglass to DIN4102 Class B standard. The ceramic cable connectors are rated to withstand temperatures to 600° C. To facilitate confidence testing at regular intervals, as well as during emergencies, the THL-1 accommodates fault monitoring (in conjunction with external equipment) to the EN 54 standard.
The loudspeaker also offers six mounting holes, allowing it to be fixed to threaded rods or bolts attached to the tunnel soffit or unistrut.