A device may store a subset of a plurality of head-related transfer functions (HRTFs) for emulating stereo sound from a source in three-dimensional (3D) space, each of the HRTFs corresponding to a direction from which the stereo sound is perceived to arrive, by a user hearing the stereo sound. The device may also obtain a first direction from which first stereo sound is perceived to arrive, by the user and determine whether the subset of the plurality of HRTFs includes a first HRTF corresponding to the first direction, wherein the plurality of HRTFs include the first HRTF. Further, the device may select two HRTFs in the subset of the HRTFs, wherein directions that are associated with the two HRTFs are closer to the first direction than directions of other HRTFs in the subset of the HRTFs;