Exciter loudspeakers: How structure-borne sound converters open up new sound dimensions

Sound from unexpected corners: This is how structure-borne sound converters enable new concepts

There are many underappreciated technologies in the world of audio engineering. One of them is the exciter or "structure-borne sound converter"! This technology opens up new avenues in the conception and implementation of audio solutions, promising unprecedented possibilities. Discover why you, an audio enthusiast, tinkerer or DIY speaker builder, want to take a closer look at exciters.

What are exciters, or structure-borne sound converters?

Exciters, or "structure-borne sound converters", are small, lightweight devices that create sound waves by causing a surface to vibrate. In contrast to conventional loudspeakers, which generate sound through vibrations in a cone-shaped diaphragm and in a loudspeaker housing, an exciter uses almost every imaginable surface as a resonance body.

Why exciter speakers were – and are – a revolution

Exciters open the door to completely new areas of application. You could turn a glass door, a table top, the underside of a chair seat or even the ceiling into a speaker – the possibilities are almost limitless.

Have you ever dreamed of not only hearing music, but also feeling and seeing it? This is possible with exciters. The direct vibration of the surfaces on which the exciters are attached creates an intense immersive sound experience that you can feel and hear.

Areas of application for exciter loudspeakers

Exciters are finding more and more applications in a variety of areas. Here are a few examples of where they are already being used:

  1. In the construction industry, exciters can be built into walls, ceilings or floors to turn them into loudspeakers. This allows architects and builders to fill spaces with sound without the need for visible speakers. In buildings, structure-borne sound converters make unobtrusive, space-filling sound transmission possible.
  2. In vehicle technology, exciters are particularly suitable in the automotive sector, for example to convert the dashboard or door panels into loudspeakers. The result is a rich sound that enhances the driving experience.
  3. In advertising and marketing, exciters can be built into posters, displays or even packaging. This allows creative packaging designers to create sound where previously "only" visual branding was possible. This increases attention and stays in the memory.
  4. In art and culture, artists and creatives use exciters to create interactive installations. Visitors can go on a journey through the world of sound. This is good for artists, because normal speaker boxes do not fit into every material work of art. Sound artists use exciters to create unique sound installations where the space itself becomes the instrument. Interactive installations can invite visitors to become sound creators themselves by making different materials and surfaces sound.
  5. In medical technology, physicians can use a structure-borne sound converter for the targeted stimulation of tissue in ultrasound applications.
  6. In gaming and VR technology, exciters open up new possibilities by providing haptic feedback, ensuring an immersive experience.

Especially in cars, exciters offer a range of possible applications for high-quality sound within the interior of the vehicle. One important advantage is the considerable reduction in materials needed. A few exciters are enough to provide the performance of a larger number of conventional speakers. They are mounted directly on parts of the vehicle, such as the interior panelling or the window panes, and turn them into sound converters. The result is a room-filling sound experience that seems to come from different directions.

The use of exciters also reduces the need for extensive cabling. This simplifies vehicle design and contributes to leaner, more efficient vehicle architecture. Fewer cables means less weight, less installation time and fewer potential sources of error. So the use of exciters offers a clear win-win situation – optimised sound with reduced use of materials and less complexity.

In-depth review: how does an exciter work?

As a loudspeaker with no diaphragm, an exciter consists of three main components:

  • a mass capable of vibrating
  • a terminal for electrical connection to the amplifier
  • a mounting plate for attachment to the installation surface

Physical principles of exciter technology

Exciter technology is based on sound transmission. When an exciter causes a surface to vibrate, sound waves are created that propagate through the material. These vibrations are mechanical waves that are caused by the arrangement and movement of atoms and molecules in the material. Depending on the nature of the material and the excited surface, the sound produced can vary greatly. This is because the speed at which sound waves propagate in a material and how the material damps the vibrations affect how the sound is perceived.

The mounting plate plays a crucial role in the sound quality and characteristics of a structure-borne sound converter

The larger the plate, the fuller the sound, with an emphasis on the low-frequency components. Conversely, the sound appears thinner with smaller plates.

The weight of the plate is also important. Light plates are advantageous because the efficiency – the ratio between sound pressure levels and input power – decreases with increasing weight. Ideally, the plate should be rigid and made of a non-magnetic material. The reason is that exciters have a permanent magnet and would therefore be precharged.

The shape of the plate also has a big impact on the sound. Components with large surfaces often have a positive effect.

When wiring, you should make sure that the resonance of the cables does not cause any interference. The classic situation is where cables touch the mounting plate or a sensitive body in the vicinity due to the resulting movement. If necessary, covering the cables with foam helps.

The best approach for maximum fun with exciters – just experiment!

There are a few things to consider when using exciters. Choose the soundboard carefully: it should be light, rigid and non-magnetic. Experiment with different shapes and sizes to find the ideal sound. Position the exciter so that it causes the largest possible area to oscillate.

Conclusion – exciters have a future in many industries

Exciters or structure-borne sound converters are revolutionising audio technology. They make unique worlds of sound possible by transforming almost any surface into a speaker. Whether in architecture, marketing, art or medical technology, exciters are opening up innovative possibilities.

The relevance of the exciter for the automotive sector deserves special mention. Here they enable an immersive sound experience by transforming parts of the vehicle, such as the interior panelling or the window panes, into sound converters. They also reduce the use of materials and the complexity of the wiring, which contributes to more efficient vehicle architecture. Despite certain challenges, such as their dependence on the material and shape of the excited surface, it is clear that exciters are a future-oriented technology.

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