PROGRAMM - DAGA 2012

214 DAGA 2012 ProgrammMi. 9:20 hassium 3.02 Akustische Messtechnik 1Modal sound field representation of HRTFsM. Pollow, P. Dietrich, B. Masiero, J. Fels und M. VorländerInstitut für Technische Akustik, RWTH AachenHRTFs are usually stored as frequency spectra or impulse responsesobtained at a set of discrete points at a fixed distance from the head.While it is straightforward to access this information at the given pointsor directions of interest, it is more difficult to obtain values for the HRTFsfor other points in the 3D space.Alternatively, the HRTFs can be formulated reciprocally by representingthem as a set of modal components of an outgoing spherical wave. Thediscrete data is thus transformed into a spatially continuous representationof the HRTFs, enabling the evaluation at arbitrary points in bothnear-field and far-field.In this contribution, the described method is applied to measured individualHRTFs, as described in the previous contribution by Masiero et. al.(DAGA 2012). Hereby, the imperfections of the measurement equipmentare compensated to obtain more accurate results. Different centeringtechniques are compared with the aim to achieve a compact data setthat allows for the calculation of the HRTF at any point in space.Mi. 9:45 hassium 3.02 Akustische Messtechnik 1Time Efficient Measurement Method for Individual HRTFsP. Dietrich, B. Masiero, M. Pollow, B. Krechel und M. VorländerInstitut für Technische Akustik, RWTH AachenAn optimized multi-channel measurement setup for the acquisition of individualHRTFs in anechoic environments has been developed. This kindof measurement is usually time-consuming, if high spatial resolution isrequired. Since persons have to stand on a turntable for several minutesthe results might lack accuracy due to unwanted movements of thehead.A recently introduced technique allows simultaneous playback of multipleexponential sweeps through several loudspeakers by even consideringslightly non-linear behavior [Majdak2007]. This approach directlyleads to a significant reduction of required measurement duration withoutloss of quality compared to a conventional subsequent measurement.An entirely different approach uses a continuous measurementmethod of a rotating person with a single loudspeaker to speed up theHRTF measurement on a horizontal ring [Enzner2009]. In this case themeasured system should be considered as slightly time-variant dependingon the rotational speed.We propose a novel approach, combining these methods in order toachieve shorter measurement times. The effects of the time-variance