A method of estimating an individualized head-related transfer function (HRTF) and an individualized interaural time difference function (ITDF) of a particular person in a computing device, the method comprising the steps of: a) obtaining a plurality of data sets (Li, Ri, Oi), each data set comprising a left audio sample (Li) recorded using a left in-ear microphone and a right audio sample (Ri) recorded using a right in-ear microphone and orientation information (Oi) originating from an orientation unit (604; 704; 804), the left audio sample and the right audio sample and the orientation information of each data set being simultaneously captured in an arrangement wherein: the left in-ear microphone being inserted in a left ear of the person, and the right in-ear microphone being inserted in a right ear of the person, and the orientation unit being mounted on or to a head of the person, and the person being located at a distance from a loudspeaker (602; 702; 802), and the loudspeaker being arranged for rendering an acoustic test signal comprising a plurality of audio test-fragments (Ci), and the person turning a head in a plurality of different orientations during the rendering of the acoustic test signal; b) storing the plurality of data sets (Li, Ri, Oi) in a memory; c) estimating a direction of the loudspeaker with respect to the head of the person, for each data set (Li, Ri, Oi) stored in the memory; d) estimating the individualized interaural time difference function of the person, based on the plurality of data sets (Li, Ri, Oi) stored in the memory and based on the directions estimated in step c); e) estimating the individualized head-related transfer function of the person, based on the plurality of data sets (Li, Ri, Oi) recorded using the in-ear microphones and stored in the memory and based on the directions estimated in step c). a) obtaining a plurality of data sets (Li, Ri, Oi), each data set comprising a left audio sample (Li) recorded using a left in-ear microphone and a right audio sample (Ri) recorded using a right in-ear microphone and orientation information (Oi) originating from an orientation unit (604; 704; 804), the left audio sample and the right audio sample and the orientation information of each data set being simultaneously captured in an arrangement wherein: the left in-ear microphone being inserted in a left ear of the person, and the right in-ear microphone being inserted in a right ear of the person, and the orientation unit being mounted on or to a head of the person, and the person being located at a distance from a loudspeaker (602; 702; 802), and the loudspeaker being arranged for rendering an acoustic test signal comprising a plurality of audio test-fragments (Ci), and the person turning a head in a plurality of different orientations during the rendering of the acoustic test signal; the left in-ear microphone being inserted in a left ear of the person, and the right in-ear microphone being inserted in a right ear of the person, and the orientation unit being mounted on or to a head of the person, and the person being located at a distance from a loudspeaker (602; 702; 802), and the loudspeaker being arranged for rendering an acoustic test signal comprising a plurality of audio test-fragments (Ci), and the person turning a head in a plurality of different orientations during the rendering of the acoustic test signal; b) storing the plurality of data sets (Li, Ri, Oi) in a memory; c) estimating a direction of the loudspeaker with respect to the head of the person, for each data set (Li, Ri, Oi) stored in the memory; d) estimating the individualized interaural time difference function of the person, based on the plurality of data sets (Li, Ri, Oi) stored in the memory and based on the directions estimated in step c); e) estimating the individualized head-related transfer function of the person, based on the plurality of data sets (Li, Ri, Oi) recorded using the in-ear microphones and stored in the memory and based on the directions estimated in step c).