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Noise control of ventilation ducts


The EolAc is an active silencer that reduces low frequency noise generated by ventilation networks in buildings and by suction and/or ventilation systems in industry. The active device is based on the EOLANE process patented by TechnoFirst.

The ActA active silencer is also equipped with traditional passive attenuation devices such as rock wool and an acoustic bulb in order to treat high and medium frequencies as well.
The result of this combination of traditional passive techniques with active noise canceling technology is optimal noise reduction across all audible frequencies (20Hz-20kHz).

Eolac controle bruit gaine de ventilation


The EolAc is a cylindrical or rectangular sound trap equipped with an acoustic bulb in which are installed a loudspeaker and two microphones connected to a dedicated electronic card. The upstream microphone picks up the sound and transmits it to the electronics which analyzes it and generates the counter noise which is then emitted by the loudspeaker. The downstream microphone analyzes the resulting noise and adjusts the processing algorithms in real time to guarantee maximum and continuous efficiency.


The graph opposite shows an attenuation curve measured on an Eolac at the mouth outlet.

Main advantages:
  • Very good attenuation of noise radiated in the ducts (air flow noise and fan noise), mainly at low frequencies.
  • Very low pressure drop.
  • Very simple implementation.
  • Suitable for new installations as well as for upgrading existing installations to acoustic standards.

Technical characteristics

Cylindrical Eolacs are a range of silencers that allow them to adapt to a wide variety of environments:
  • Internal duct diameter between 250 and 630 mm as standard
  • Air flow treatment up to 10,000 m3/hour
  • Power supply: 230V.
Standard Eolacs are manufactured and installed by subcontractors certified by TechnoFirst and to whom TechnoFirst supplies the electronic elements of the system (contact us).

Other Solutions

For all requests concerning non-standard products derived from the Eolac range and using the EOLANE process, TechnoFirst carries out, on request, Studies and Projects to adapt its products for their installation in its customers’ systems:
  • ASCa: input and output
  • ACTA: inside