Thesis

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New approaches for active noise control headphones

Authors Flock, M.
Year 2014
Thesis Type Doctoral thesis
Topic Sonification
Abstract Headphones with active noise control (ANC) cancel ambient noise by playing back destructively interfering ’anti’-noise. This thesis describes new approaches for feedforward as well as feedback ANC and treats the variability in the acoustics of headphones which results from differently tight wearing situations. For feedforward ANC headphones, a new adaptive approach is presented that is based on a linear combination of parallel IIR filters. This approach is powerful because it allows for an analogue implementation. Besides, it is shown how the tightness of the headphones can be detected online by means of digital signal analysis. Digital technology always suffers from the increased latency due to signal conversions. This is especially problematic in feedback ANC because the increased latency can lead to instability. A prediction filter is thus suggested to compensate for this latency. Additionally, a method for detecting changes in the wearing situation is developed for feedback ANC, too. Finally, a procedure for the assessment of ANC headphones is derived over a regression analysis with subjective user ratings.
URL http://phaidra.kug.ac.at/o:8645
Supervisors Höldrich, R.