Helmholtz resonators
The principle of the Helmholtz resonator
The Helmholtz resonator is one of the most fundamental concepts in acoustics. It describes a system consisting of a vibrating air plug and a coupled air volume – a principle we encounter constantly in everyday life: from blowing through a bottle neck to the resonating body of a guitar.
The physical model: mass and spring
To understand how it works, the image of a bottle serves as an ideal model:
The air plug (mass)
The air in the bottle neck forms an acoustic mass, the inertia of which is determined by the geometry of the neck.
The air volume (spring)
The trapped air in the bottle's belly acts like an elastic spring, pushing back the air plug that was pushed in.
Together they form a vibrating system with a specific resonant frequency . This is exactly the sound you hear when you blow into the bottle.
From resonance to absorption
While musical instruments use resonance for amplification, an absorber requires energy to be deliberately extracted. This is achieved through controlled damping : The vibrating air in the opening is slowed down by friction, thus converting sound energy into heat.
Technical implementation: Microperforation (HSA3)
In room acoustics, this principle is often applied over large areas using perforated panels. A technological highlight here is the micro-perforation of the HSA3:
Advantages of HSA3 technology
- Tiny openings: Instead of large holes, the HSA3 uses a multitude of microscopic openings with a radius of less than 1 mm.
- Integrated damping: Due to the minimal dimensions, the friction directly on the perforated walls is so high that no additional porous material (such as fleece or mineral wool) is needed.
- Precise tuning: By combining hole size, spacing and cavity depth, the maximum effect can be defined exactly for specific frequencies.
The HSA3 thus combines classic physical laws with state-of-the-art manufacturing technology for highly efficient and aesthetic room acoustics.