Sound Actuators "We Can Completely Replace Speakers"

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Dimitrios Patsouras has been working for many years on actuators that turn interior components into soundboards. Now the technology is ready for series production. The Director of Acoustic Solutions at Aumovio Engineering Solutions describes the benefits.

The supplier Aumovio has integrated actuators into a screen unit. The technology makes the surface vibrate, producing sound. The system, called "Ac2ated Sound" (pronounced like actuated), can be used to specifically draw drivers' attention to the displayed content. Some automakers, for example, use an avatar positioned as an assistant on the central screen. With the actuator technology, the voice of the avatar can be generated directly from its position on the display.

The technology can also be used to completely replace traditional speakers in vehicles. Dimitrios Patsouras, Director of Business Segment Acoustic Solutions at Aumovio Engineering Solutions (formerly Continental Engineering Services), describes the advantages and maturity of "Ac2ated Sound."

Mr. Patsouras, you say, we are bringing sound back to its origin. What do you mean by that?

In classical musical instruments like violins, cellos, or pianos, the body, or casing, ultimately serves as the soundboard. The idea behind "Ac2ated Sound" was similar. We see the vehicle as a complex soundboard. It consists of many components and materials with specific properties. When orchestrated together, it creates a symphony orchestra.

How does "Ac2ated Sound" work in detail?

We use actuators that set vehicle parts into vibration. These then act as resonators and produce sound. We use components such as pillar trims or the headliner for sound generation. Additionally, the same actuator-based approach can be used to generate external sounds for the—now mandatory in many countries—Acoustic Vehicle Alerting System.

In the meantime, it has been quiet. Eight years after the initial presentation, you have now introduced new use cases and partnerships.

We screened the entire market for suitable actuators. We found some that worked acoustically, but none met the high automotive standards for durability. About three years ago, we realized: if we want to open up a new market, we need our own product. Now we are reaching a maturity level suitable for industrialization. We plan to start production at the end of next year.

In which vehicle category?

The focus is initially on premium vehicles, particularly with manufacturers where limited installation space is a concern. Here, the volume and weight of our components play a significant role. However, performance is also crucial. As the demand for immersive sound experiences continues to grow, we are confident that the product can successfully scale to the volume market in the next phase.

Do your customers need new approaches for integrating the audio system?

The electronic connectivity remains unchanged. We can build on existing infrastructure. Through large-area excitation, we achieve immersive soundscapes with fewer components. Premium vehicles today incorporate over 30 speakers. We achieve comparable performance with only twelve to fifteen actuators and can save up to eight kilograms of weight, depending on the vehicle architecture.

Each actuator behaves differently depending on its installation position and the respective material. This requires careful tuning as well as adjustments in the specification and integration strategy.

In which regions do you want to market the product?

We produce in Germany, and our first customers are from Europe. So we are starting here, but we also aim to operate outside of Europe.

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Does "Ac2ated Sound" enable additional functions?

Primarily, we can completely replace speakers. However, new applications emerge. In headrests or roofliners, speakers are heavy or sometimes impossible to integrate. Door speakers are a very good example. They are standard in every vehicle, but everyone knows that when an object is placed in the door compartment, it can cause annoying rattling noises. Doors are sensitive areas with many attached components, such as window regulators, wires, and cables. With our approach, we can move away from doors altogether. At the same time, space is saved: customers gain the flexibility to place actuators wherever their design best allows—thereby saving space and weight.

Generating sound at knee level is not good.

Historically, the cavities in doors were unused, and speakers could therefore be easily integrated there. Even though this solution has become an industry standard, it is not necessarily optimal. With increasingly demanding customer needs, the industry will gradually move toward more individualized solutions, such as actuators in pillar trim.

Another problem: With some hands-free systems, outsiders can overhear the call.

When I connect the actuator to an interior panel, it strongly directs sound inward, while the external sound portion is reduced. Placing it on the metal body results in more sound projected outward. I can focus: only inward, only outward, or both. Using the same components, we can also suppress noise, such as from the wheels. Targeted sound design, for example through the headrest, becomes even more important here to enhance the privacy of occupants during phone calls or media use.

How durable are the actuators?

In terms of durability, our goal is for the actuators to outlast the entire lifespan of the vehicle. The components are designed accordingly—for example, we use steel springs instead of textile materials, ensuring higher temperature resistance and robustness. Conventional subwoofers often lose their specified performance at interior temperatures of 50 to 60 degrees.

We have designed the actuators so that they can be removed, refurbished, and reused in new applications after the end of vehicle use—in the spirit of a circular economy and waste reduction.

How does an exchange work?

We have two types of actuators: Bass and Wide Range. The bass actuator is screwed in like a wheel bolt. The Wide Range is clipped or glued, using a removable adhesive connection.

What are the technical limits?

I see barriers more in our imagination. Customers often can't imagine that a plastic panel can deliver comparable sound quality. The technology will prevail. It’s just a matter of time.