Most PA systems are pretty frustrating in the garbled sound quality they provide. But at vivaNext the engineers have worked hard to design the optimal public address system for your new vivastations. There’s nothing worse than knowing something important is being said, but not being able to understand it or hear it properly.
To make sure the new PA system is always audible, we started with an acoustic analysis study using special “Enhanced Acoustic Simulator for Engineers” (EASE) software. This study analyzed the two elements most critical to sound: Sound Pressure Level (SPL) and Speech Transmission Index (STI). The SPL, measured in decibels (dB), is concerned with sound magnitude and takes into account ambient noise levels – it is the relative “loudness” of a sound. STI predicts how the equipment being used and the surrounding environment will affect the quality of the sound, and therefore how intelligible it is for you as you hear it.
First, the acoustic engineers needed to determine what effects our curved canopies and the beams and angles inside the station would have on the way sound is going to move around. Secondly, the reflection of sound by the concrete wall, floor and glass was modeled. This analysis helped predict how clear the final sound will be on the platform and in the enclosure, and also helped determine the number and placement of speakers that will be most effective in achieving clear sounds.
Following this sophisticated modeling the engineers determined that the optimal number of speakers to achieve these goals would be 12 speakers located outside of the passenger enclosure, and another 3 speakers inside.
The next challenge was to work on the volume of the speakers. The problem with PA systems in noisy places is that the ambient noise can overwhelm the volume of the PA system, making it impossible to hear what’s being said. Our solution is to use a speaker volume system that automatically adjusts when its sensors detect that the ambient noise has increased or decreased.
There are two sensors on each new Viva platform to measure noise level. This way, announcements should be audible whether there’s a bus idling in the station and trucks are moving past, or it’s nighttime and quiet. Volume control and environmental sensitivity helps determine the right sound levels without disturbing those who don’t need to hear the message.
The PA system will be used for recorded and live announcements from transit operations, such as emergency information or service changes. It will not announce bus arrivals at this time, although it does have that capability should we want to turn on that function.
Although we’ve tested the system many times, we continue to monitor the sound levels, so let us know if you can truly hear us, loud and clear.