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Master-Vortrag: Design of an Acoustic Front-End for Active Noise Cancellation in Headphone Applications

Wojciech Ruhnke
Montag, 17. Juni 2019
11:00 Uhr
Hörsaal 4G

Noise cancellation is desirable in many situations. Headphones offer a convenient way to achieve passive noise attenuation directly at the listener's ears. Additionally, noise can be attenuated by emitting a counter wave which destructively interferes with the noise. Due to rapidly evolving signal processors, active noise control methods improve and gain better performance continuously. This performance however, depends on large number of parameters. Design parameters like the choice of the actuators (loudspeaker) and the sensors (microphones) have a strong influence. Furthermore, the structure and construction of the system influence the transfer characteristics. Only a suitable design allows for good active noise cancellation.

The behavior of the system also depends on situation dependent parameters (uncertainties) that impede the active control of sound. Three different driver types are investigated in the course of this thesis, considering the system performance in the presence of uncertainties. In addition, structure design parameters such as front and back volume of headphones are investigated. Physical models of the human ear canal and an in-ear headphone structure are used to measure the influence of the parameters described above. Furthermore, lumped parameter modeling of headphone applications is considered.