An audio signal processing apparatus for processing an input audio signal to be transmitted to a listener in such a way that the listener perceives the input audio signal to come from a virtual target position defined by an azimuth angle and an elevation angle relative to the listener, the audio signal processing apparatus comprising: a memory configured to store a set of pairs of predefined left ear and right ear transfer functions, which are predefined for a plurality of reference positions relative to the listener, wherein the plurality of reference positions lie in a two-dimensional plane; a determiner configured to determine a pair of left ear and right ear transfer functions on the basis of the set of pairs of predefined left ear and right ear transfer functions for the azimuth angle and the elevation angle of the virtual target position; and an adjustment filter configured to: adjust a delay between the left ear transfer function and the right ear transfer function of the determined pair of left ear and right ear transfer functions and a frequency dependence of the left ear transfer function and the right ear transfer function of the determined pair of left ear and right ear transfer functions according to an adjustment function, wherein the adjustment function is a function of the azimuth angle and/or the elevation angle of the virtual target position, to give an adjusted left ear transfer function and an adjusted right ear transfer function; and filter the input audio signal on the basis of the adjusted left ear transfer function and the adjusted right ear transfer function in order to obtain a left ear output audio signal and a right ear output audio signal, wherein the adjustment filter is configured to filter the input audio signal on the basis of the determined pair of left ear and right ear transfer functions and the adjustment function by: convolving the adjustment function with the left ear transfer function and by convolving the result with the input audio signal in order to obtain the left ear output audio signal; and by convolving the adjustment function with the right ear transfer function and by convolving the result with the input audio signal in order to obtain the right ear output audio signal. a memory configured to store a set of pairs of predefined left ear and right ear transfer functions, which are predefined for a plurality of reference positions relative to the listener, wherein the plurality of reference positions lie in a two-dimensional plane; a determiner configured to determine a pair of left ear and right ear transfer functions on the basis of the set of pairs of predefined left ear and right ear transfer functions for the azimuth angle and the elevation angle of the virtual target position; and an adjustment filter configured to: adjust a delay between the left ear transfer function and the right ear transfer function of the determined pair of left ear and right ear transfer functions and a frequency dependence of the left ear transfer function and the right ear transfer function of the determined pair of left ear and right ear transfer functions according to an adjustment function, wherein the adjustment function is a function of the azimuth angle and/or the elevation angle of the virtual target position, to give an adjusted left ear transfer function and an adjusted right ear transfer function; and filter the input audio signal on the basis of the adjusted left ear transfer function and the adjusted right ear transfer function in order to obtain a left ear output audio signal and a right ear output audio signal, wherein the adjustment filter is configured to filter the input audio signal on the basis of the determined pair of left ear and right ear transfer functions and the adjustment function by: convolving the adjustment function with the left ear transfer function and by convolving the result with the input audio signal in order to obtain the left ear output audio signal; and by convolving the adjustment function with the right ear transfer function and by convolving the result with the input audio signal in order to obtain the right ear output audio signal. adjust a delay between the left ear transfer function and the right ear transfer function of the determined pair of left ear and right ear transfer functions and a frequency dependence of the left ear transfer function and the right ear transfer function of the determined pair of left ear and right ear transfer functions according to an adjustment function, wherein the adjustment function is a function of the azimuth angle and/or the elevation angle of the virtual target position, to give an adjusted left ear transfer function and an adjusted right ear transfer function; and filter the input audio signal on the basis of the adjusted left ear transfer function and the adjusted right ear transfer function in order to obtain a left ear output audio signal and a right ear output audio signal, wherein the adjustment filter is configured to filter the input audio signal on the basis of the determined pair of left ear and right ear transfer functions and the adjustment function by: convolving the adjustment function with the left ear transfer function and by convolving the result with the input audio signal in order to obtain the left ear output audio signal; and by convolving the adjustment function with the right ear transfer function and by convolving the result with the input audio signal in order to obtain the right ear output audio signal.