The cost of using traditional labour to trace loudspeaker circuits can be prohibitive where access is difficult, intrusive or where cables are hidden. It is not always obvious to tell in which order loudspeakers are on a network. If cable installation diagrams don’t exist and access to the cables is not available then how can any changes to the network be planned?  This was exactly the problem our client had within an extremely large and sensitive building fitted with just fewer than one thousand loudspeakers.

We needed to provide a fast solution to a seemingly impossible problem and there is nothing currently available to carry out such a task.  We set about developing a special type of sound which could be injected into the system which had to meet two difficult criteria:

1. It must not be heard by human ears.
2. It must change sequentially for every loudspeaker on the network.

We then developed a measuring device that could detect the sound and accurately present the results.  We applied some acoustic engineering principles and set about producing a variety of sounds.  We tested these with different people of varying age for audibility and then made a mock up within our workshop to test the theory and our ability to measure the sound.

The result of this development allows B.L. Acoustics to provide a service which aids the tracing of high impedance loudspeaker installations using remote handheld test equipment. In combination with traditional tracing methods for verification this can provide better than 90% accuracy, enabling drawings to be produced detailing the probable cable routes.

The remote testing method does not require each speaker to be taken off of its mounting thus avoiding induced faults onto lines which is considered to be a major problem with the more intrusive type of survey. Building plans are marked with loudspeaker & circuit indicative cable installation detail.