# Auralization of High-Order Directional Sources from First-Order RIR Measurements
); [EMAIL_ADDRESS] (F.Z.) 1 Institute of Electronic Music and Acoustics, University of Music and Performing Arts Graz,  
Infeldgasse 10/III, 8010 Graz, Austria; [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (F.Z.) 1 Institute of Electronic Music and Acoustics, University of Music and Performing Arts Graz,  
Infeldgasse 10/III, 8010 Graz, Austria; [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (F.Z.) 1 Institute of Electronic Music and Acoustics, University of Music and Performing Arts Graz,  
Infeldgasse 10/III, 8010 Graz, Austria; [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (F.Z.) 1 Institute of Electronic Music and Acoustics, University of Music and Performing Arts Graz,  
Infeldgasse 10/III, 8010 Graz, Austria; [EMAIL_ADDRESS] (F.Z. ); [EMAIL_ADDRESS] (F.Z.) 1 Institute of Electronic Music and Acoustics, University of Music and Performing Arts Graz,  
Infeldgasse 10/III, 8010 Graz, Austria; [EMAIL_ADDRESS] (F.Z.) 1 Institute of Electronic Music and Acoustics, University of Music and Performing Arts Graz,
of controllable higher-order directivity by [PERSON] et al. [5] showed that both the auditory source distance and the apparent source width are influenced by the directivity. [PERSON] and [PERSON] [6] found source directivity to modify clarity, localization, and timbre. In terms of localization, [PERSON] et al. [7] investigated how beam-formed source directivity of an icosahedral loudspeaker (IKO) produces auditory events that can be shifted between physical source and wall reflections, or follow traceable trajectories. [PERSON] and [PERSON] [8] demonstrated the influence of source directivity on reverberation time and clarity, and they found a clear effect of source directivity in their auralization experiment. _Why receiver directivity matters_: Higher-order receiver directivities have been recently proved useful to characterize room acoustical measurements, see, e.g., in [9; 10], and moreover, e.g., to identify the sound field isotropy in various reverberant rooms [11; 12]. In the targeted auralization scenario, the receiver is obviously a listener and thus the various sound propagation paths arriving at the ears are weighted by their head related transfer functions (HRTFs). In order to employ an arbitrary receiver directivities during auralization or postprocessing, e.g., individualized HRTFs, the measured room-dependent part also has to be generic and has to facilitate higher-order receiver directivities. _Why we suggest Ambisonics:_ Directivities are typically measured under anechoic conditions, with a microphone array surrounding the source, or a loudspeaker array surrounding the receiver, respectively. For comparability and a unified directional interpolation, a representation of those directivities in terms of spherical harmonic expansion coefficients is beneficial, see, e.g., in [13; 14]. Consequently, a generalized representation of the room-dependent part that interfaces with both the source and receiver directivities should also be expanded in spherical harmonics, i.e. represented in Ambisonics. Furthermore, [PERSON] et al. [15] found that dynamic binaural rendering (incorporating head rotations) significantly improves localization accuracy. Moreover, using Ambisonics has its benefits in facilitating dynamic rendering efficiently, as it implements dynamic sound scene rotation by a time-variant matrix multiplication [16; 17], whereas the convolution with MagLs [18] HRIRs in the spherical harmonics domain remains time-invariant. _SRD ARIR_: According to the above considerations, we propose a source-and-receiver-directional (SRD) higher-order Ambisonic room impulse response (ARIR) as representation of the room-dependent parts of auralization. Measuring such a SRD ARIR requires high-order spherical microphone and loudspeaker arrays, which are recently used for room acoustical measurements or propagation path identification [19; 20] or as well for studying the concert hall preference [14].