Acoustic liners for future aircraft engines will have to achieve contradictory goals: maintaining a strong absorption at low frequencies while reducing the treated surface area and liner thickness. The purpose of this paper is to review several concepts in the development of transducer-based acoustic liners. The use of transducers enables the coupling of several physical processes: acoustics, mechanics and electronics. As shown in previous work, this can lead to highly efficient devices enabling low frequency absorption with thin liners. The present work aims at better understanding the key phenomena governing acoustic absorption and frequency range available for a given liner thickness. This can be done by adding a thin mechanical structure with thin slits. These slits are cut in the structure and form an acoustic short-cut between the front and the back of the device. Coupled with a back- end cavity, it has been shown that the results of adding thin slits could be beneficial in terms of acoustic absorption, bandwidth and frequency shifting. In order to study those phenomena, the Transfer Matrix Method and the Finite Element Method will be used. These prediction methods will be compared and some experimental results will be presented in order to validate the models and better understand the effects of fluid inertia and visco-thermal losses in the slits.