For optimum performance the sonic horn manufactured by Primasonics® is exponential in shape, in other words it is designed in the shape of a 'bell' section. The reason for this shape is quite simple; the acoustic sound wave frequencies produced by each of our six selected frequency models are extremely pure in tone and powerful in performance due to this design. To understand better the need for the exponential, or bell shape of the sonic horn, a short interesting history of the bell may be helpful.

Firstly the definition of the bell as defined in the Encyclopaedia Britannica - "a special hollow vessel usually of metal, but sometimes of horn, wood, glass, or clay, struck near the rim by an interior clapper or exterior hammer or mallet to produce a pure ringing tone. Bells may be categorized as idiophones, instruments sounding by the vibration of resonant solid material, and more broadly as percussion instruments."

The early purpose of bells were to create clear power frequency tones which would travel long distances and therefore the exponential shape became established as the only way that all these goals could be met. For sonic horns, now referred to in industrial terms as acoustic cleaners, the important part in this definition is the vibration of resonant solid material, the bell shape resonates sound far more effectively.

The bell is primarily a musical instrument, designed to be used as part of a musical piece, or rung to invite parishioners near and far to their local Sunday service and as well as this the bell has been used to warn of impending danger.

The most famous bell in the United Kingdom is Big Ben and is housed in the tower below on the Houses of Parliament. Big Ben is 9'-0"/2.74m diameter, 7'-6"/2.3 high, and weighing in at 13 tons 10 cwts 3 qtrs 15lbs (13,760 Kg).

On the stroke of midnight every New Year's Eve people wait patiently to hear Big Ben chime in the New Year.

Pictured left is the Westminster Parliament Building and below right is the actual bell 'insitu'.

This bell has been consistently emitting true frequency tones across London since 31st May 1859, when the bells of the Great Clock of Westminster rang across London for the first time.

It is perhaps in the church where the bell is most recognisable. They have been used here for centuries to announce the beginning of the services that take place.

On a Sunday morning in villages all over the UK, bells can be heard ringing, the pure sound frequencies drifting through the air bringing the unmistakeable sound of the bell to the local people over a wide area.