Active noise control (ANC) techniques are based on the emission of an antiphase signal in order to cancel
the noise produced by a primary source. ANC has been successfully applied especially for reducing noise
in confined environments, such as headphones and ducts. In this study, we present an application of ANC
concepts to the design of an anti-noise barrier for an outdoor environment and its experimental testing.
Even though passive techniques are effective in noise reduction at middle-high frequencies, they become
less efficient at low frequencies (below 300 Hz) due to the limited dimensions of commonly deployable
barriers. In this paper, we analyze the properties of a low-cost active noise system able to efficiently operate
on stationary, almost pure-tone, low-frequency noise, such as that produced by electrical transformers
and reactors in power and transformation plants. A prototype has been implemented and on-the-field
experimental tests have been carried out. The results (confirmed also by numerical simulations) demonstrate
a remarkable efficiency in the far field, with a reduction up to 15 dB with respect to the absence of
the ANC system.