Another famous bell is the Liberty bell. First chiming out true tones of frequency from the tower of Independence Hall it summoned the local citizens to be present for the first public reading of the Declaration of Independence by Colonel John Nixon on the 8th July 1776.

In actuality, bells have been used since more or less the beginning of civilisation. Amongst other things bells were used to frighten away unwanted and evil spirits and change the weather. By the time of the Middle Ages, the understanding of the mechanics of the bell improved, they were better crafted than their crude ancestor bells and even given their own towers.

The bell pictured is a Meneely made bell. The Meneely Company were the main manufactures of the bell in 19th and 20th century USA.

It is important to be aware that the shape of the bell has remained constant for centuries and centuries. This is because this shape, the exponential shape, is ideal for obtaining maximum acoustic power over long distances and at pure selected frequencies. Primasonics® utilised this bell shape and the bells ability to offer such clear tones at pre-selected wavelengths and at maximum power in the design of all their special range of acoustic cleaners. All our acoustic horn designs have pure fundamental frequencies of between 350 Hz and 60 Hz.

In the diagram below is shown the Primasonics® exponential sonic horn bell section on the left. Compare this with the cheaper, less effective conical bell section on the right. We would never use this straight conical design as we believe it to be detrimental to achieving both pure selected sound frequencies and also in utilising the maximum power of the particular Primasonics® Acoustic Cleaner.

To summarize, the correct design of the bell sections are critical. The history of the bell has proved that the exponential bell shape is the only true spare.

Thus the exponential shape of the bell sections in Primasonics® Acoustic Cleaners or Sonic Horns is vital in order to achieve both pure, powerful selected frequency tones and to cover a much larger area. Primasonics® Design Engineers have learned a powerful lesson from history which is now transposed into providing the best range of sonic horns available.