Audio Signal Processing Apparatus and Method

An audio signal processing method for processing an input audio signal, comprising:

• determining a pair of left ear and right ear transfer functions on a basis of a set of pairs of predefined left ear and right ear transfer functions for an azimuth angle and an elevation angle of a virtual target position relative to a listener, the pairs of the predefined left ear and right ear transfer functions being predefined for a plurality of reference positions relative to the listener, and the reference positions lying in a two-dimensional plane;
• filtering the input audio signal on a basis of the determined pair of the left ear and right ear transfer functions and an adjustment function configured to adjust a delay between a left ear transfer function and a right ear transfer function of the determined pair of the 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 the left ear and right ear transfer functions as a function of the azimuth angle or the elevation angle of the virtual target position in order to obtain a left ear output audio signal and a right ear output audio signal;
• and
• transmitting the left ear output audio signal and the right ear output audio signal to the listener to enable the listener to perceive the input audio signal arriving from the virtual target position defined by the azimuth angle and the elevation angle relative to the listener.

A computer program product comprising a non-transitory computer readable storage medium storing program code thereon for processing an input audio signal, the program code comprising instructions for executing a method that comprises:

• determining a pair of left ear and right ear transfer functions on a basis of a set of pairs of predefined left ear and right ear transfer functions for an azimuth angle and an elevation angle of a virtual target position relative to a listener, the pairs of the predefined left ear and right ear transfer functions being predefined for a plurality of reference positions relative to the listener, and the reference positions lying in a two-dimensional plane;
• filtering the input audio signal on a basis of the determined pair of the left ear and right ear transfer functions and an adjustment function configured to adjust a delay between a left ear transfer function and a right ear transfer function of the determined pair of the 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 the left ear and right ear transfer functions as a function of the azimuth angle or the elevation angle of the virtual target position in order to obtain a left ear output audio signal and a right ear output audio signal;
• and
• transmitting the left ear output audio signal and the right ear output audio signal to the listener to enable the listener to perceive the input audio signal arriving from the virtual target position defined by the azimuth angle and the elevation angle relative to the listener.