Browsing by Author "Kuosmanen, Kai"

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    Efficient implementation of a natural hear-through algorithm on wireless headphones
    (2018-12-10) Kuosmanen, Kai; Pakarinen, Jyri; Sähkötekniikan korkeakoulu; Lokki, Tapio
    Hear-through is a functionality where microphones built into headphones record ambient sounds and play them to the user either as-is or mixed with other material such as music. Depending on the properties of the microphone and the headphone transducer the hear-through sound may appear more or less unnatural. There are several reasons for this, such as changes in ear acoustics caused by insert-type earphones and the non-ideal frequency response of the entire system. Naturalness of the sound can be improved by modifying it to correspond better to the frequency response of an average human ear. The acoustic changes caused by the earphones can be cancelled by filtering the system response to match that of an open ear. The open ear response is easiest to measure using an anthropometric dummy head, a measurement instrument designed to mimic the acoustic properties of the outer and middle ear of an average person. This work explores various methods to perform the equalisation in such a manner that the frequency spectrum of the filtered signal matches that of the dummy head as closely as possible. The earphones used in the work are battery-operated wireless prototype set, containing a Bluetooth radio and a digital signal processing unit. The main focus of the work is in the efficiency and simplicity of the filtering solutions to save the limited processing capacity and to maximise the battery life.
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    Hilamikrofonit
    (2015-05-04) Kuosmanen, Kai; Turku, Julia; Sähkötekniikan korkeakoulu; Turunen, Markus