Subject: Re: [AUDITORY] Seeking advice on improving localization clarity in static binaural playback with non-individualized HRTFs From: "Picinali, Lorenzo" <l.picinali@xxxxxxxx> Date: Thu, 7 Aug 2025 12:36:58 +0000--_000_LO0P265MB3035DB22588B51A14B9E83A3BA2CALO0P265MB3035GBRP_ Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Hello Dingding, Here are my two cents on the matter; it is known that the spectral cues use= d by our hearing system to determine whether the source is in front or on t= he back are mainly between 4 and 8kHz, meaning that sources on the back mig= ht have 3-5dB less energy in that range (there usually are other bands that= are affected in a similar way, for example around 12 and 14/15kHz, albeit = the difference in dB between front and back is smaller). Similarly, elevate= d sources are likely to have a ~5-7dB boost around 7-9kHz, together with at= tenuation between 12-14kHz. I remember seeing some conference papers on improving front-back confusion = (e.g. Balan, O., Moldoveanu, A., & Moldoveanu, F. (2018). A Systematic Revi= ew of the Methods and Experiments Aimed to Reduce Front-Back Confusions in = the Free-Field and Virtual Auditory Environments. RoCHI, 24-29, for example= ) but I'm not particularly convinced such methods would work without traini= ng. The latter is a relevant point in my opinion, as if you for example enh= ance the front-back and up-down spectral differences and create a "superhum= an HRTF", you can surely train someone to use those enhanced cues and signi= ficantly improve their discrimination performances. I'd though consider thi= s approach as being more a form of "sonification" rather than spatialisatio= n, and I don't know whether this would work consistently and repeatedly wit= h untrained individuals. Best Lorenzo -- Lorenzo Picinali Professor in Spatial Acoustics and Immersive Audio Dyson School of Design Engineering Imperial College London Dyson Building Imperial College Road South Kensington, SW7 2DB, London E: l.picinali@xxxxxxxx https://profiles.imperial.ac.uk/l.picinali https://www.axdesign.co.uk/ https://www.sonicom.eu/ ________________________________ From: AUDITORY - Research in Auditory Perception <AUDITORY@xxxxxxxx>= on behalf of Dingding Yao <simon.ydd@xxxxxxxx> Sent: 07 August 2025 7:41 AM To: AUDITORY@xxxxxxxx <AUDITORY@xxxxxxxx> Subject: [AUDITORY] Seeking advice on improving localization clarity in sta= tic binaural playback with non-individualized HRTFs Dear list, I hope this message finds you well. I am reaching out to seek your advice on a question related to binaural rep= roduction. As we all know, localization ambiguities=97especially front-back= and up-down confusions=97are a common challenge when using HRTF-based bina= ural playback. Previous literature has pointed out several influencing fact= ors, such as dynamic cues (e.g., head rotation), individualized HRTFs, and = headphone equalization. However, I am particularly interested in whether it is still possible to ac= hieve a clear sense of directional perception under static listening condit= ions with non-individualized HRTFs. Specifically, even if precise localizat= ion is not attained, might there be techniques or strategies that allow lis= teners to clearly and reliably distinguish between front and back, as well = as between above and below? Any insights, relevant experiences, or useful references would be greatly a= ppreciated. I would also welcome any discussion or perspectives on this top= ic. Best regards, Dingding Yao --_000_LO0P265MB3035DB22588B51A14B9E83A3BA2CALO0P265MB3035GBRP_ Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable <html> <head> <meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3DWindows-1= 252"> <style type=3D"text/css" style=3D"display:none;"> P {margin-top:0;margin-bo= ttom:0;} </style> </head> <body dir=3D"ltr"> <div style=3D"font-family: "Times New Roman", "Times", = serif; font-size: 12pt; color: rgb(0, 0, 0);" class=3D"elementToProof"> Hello Dingding,</div> <div style=3D"font-family: "Times New Roman", "Times", = serif; font-size: 12pt; color: rgb(0, 0, 0);" class=3D"elementToProof"> <br> </div> <div style=3D"font-family: "Times New Roman", "Times", = serif; font-size: 12pt; color: rgb(0, 0, 0);" class=3D"elementToProof"> Here are my two cents on the matter; it is known that the spectral cues use= d by our hearing system to determine whether the source is in front or on t= he back are mainly between 4 and 8kHz, meaning that sources on the back mig= ht have 3-5dB less energy in that range (there usually are other bands that are affected in a similar way, f= or example around 12 and 14/15kHz, albeit the difference in dB between fron= t and back is smaller). Similarly, elevated sources are likely to have a ~5= -7dB boost around 7-9kHz, together with attenuation between 12-14kHz.</div> <div style=3D"font-family: "Times New Roman", "Times", = serif; font-size: 12pt; color: rgb(0, 0, 0);" class=3D"elementToProof"> <br> </div> <div style=3D"font-family: "Times New Roman", "Times", = serif; font-size: 12pt; color: rgb(0, 0, 0);" class=3D"elementToProof"> I remember seeing some conference papers on improving front-back confusion = (e.g. Balan, O., Moldoveanu, A., & Moldoveanu, F. (2018). A Systematic = Review of the Methods and Experiments Aimed to Reduce Front-Back Confusions= in the Free-Field and Virtual Auditory Environments. <i>RoCHI</i>, 24-29, for example) but I'm not particularly c= onvinced such methods would work without training. The latter is a relevant= point in my opinion, as if you for example enhance the front-back and up-d= own spectral differences and create a "superhuman HRTF", you can surely train someone to use those e= nhanced cues and significantly improve their discrimination performances. I= 'd though consider this approach as being more a form of "sonification= " rather than spatialisation, and I don't know whether this would work consistently and repeatedly with untrained individ= uals.</div> <div style=3D"font-family: "Times New Roman", "Times", = serif; font-size: 12pt; color: rgb(0, 0, 0);" class=3D"elementToProof"> <br> </div> <div style=3D"font-family: "Times New Roman", "Times", = serif; font-size: 12pt; color: rgb(0, 0, 0);" class=3D"elementToProof"> Best</div> <div style=3D"font-family: "Times New Roman", "Times", = serif; font-size: 12pt; color: rgb(0, 0, 0);" class=3D"elementToProof"> Lorenzo</div> <div style=3D"font-family: "Times New Roman", "Times", = serif; font-size: 12pt; color: rgb(0, 0, 0);" class=3D"elementToProof"> <br> </div> <div style=3D"font-family: "Times New Roman", "Times", = serif; font-size: 12pt; color: rgb(0, 0, 0);" class=3D"elementToProof"> <br> </div> <div class=3D"elementToProof" id=3D"Signature"> <div style=3D"font-family: "Times New Roman", "Times", = serif; font-size: 12pt; color: rgb(0, 0, 0);" class=3D"elementToProof"> <br> </div> <div style=3D"font-family: Tahoma; font-size: 10pt;" class=3D"elementToProo= f">--<br> Lorenzo Picinali<br> Professor in Spatial<span style=3D"color: rgb(0, 0, 0);"> Acoustics an= d Immersive Audio</span><br> Dyson School of Design Engineering<br> Imperial College London<br> Dyson Building<br> Imperial College Road<br> South Kensington, SW7 2DB, London<br> E: l.picinali@xxxxxxxx<br> <u><br> </u><span style=3D"color: rgb(0, 0, 0);"><a class=3D"OWAAutoLink" id=3D"OWA= 0c1fba3d-2c29-0769-5e45-ef21b4782689" href=3D"https://profiles.imperial.ac.= uk/l.picinali">https://profiles.imperial.ac.uk/l.picinali</a></span><br> <a data-auth=3D"NotApplicable" data-linkindex=3D"2" rel=3D"noopener norefer= rer" class=3D"OWAAutoLink" id=3D"OWAd5f25dab-4d74-fb16-fe0b-a1a2b6a8bb5d" t= arget=3D"_blank" href=3D"https://www.axdesign.co.uk/">https://www.axdesign.= co.uk/</a></div> <div style=3D"font-family: Tahoma; font-size: 10pt;" class=3D"elementToProo= f"><a data-auth=3D"NotApplicable" data-linkindex=3D"3" rel=3D"noopener nore= ferrer" class=3D"OWAAutoLink" id=3D"OWA34b853a7-5ccd-a252-cb05-1ccf8dbacf64= " target=3D"_blank" href=3D"https://www.sonicom.eu/">https://www.sonicom.eu= /</a></div> </div> <div id=3D"appendonsend"></div> <hr style=3D"display:inline-block;width:98%" tabindex=3D"-1"> <div id=3D"divRplyFwdMsg" dir=3D"ltr"><font face=3D"Calibri, sans-serif" st= yle=3D"font-size:11pt" color=3D"#000000"><b>From:</b> AUDITORY - Research i= n Auditory Perception <AUDITORY@xxxxxxxx> on behalf of Dingdin= g Yao <simon.ydd@xxxxxxxx><br> <b>Sent:</b> 07 August 2025 7:41 AM<br> <b>To:</b> AUDITORY@xxxxxxxx <AUDITORY@xxxxxxxx><br> <b>Subject:</b> [AUDITORY] Seeking advice on improving localization clarity= in static binaural playback with non-individualized HRTFs</font> <div> </div> </div> <div> <div dir=3D"ltr">Dear list,<br> <br> <div>I hope this message finds you well. <div><br> </div> <div>I am reaching out to seek your advice on a question related to binaura= l reproduction. As we all know, localization ambiguities=97especially front= -back and up-down confusions=97are a common challenge when using HRTF-based= binaural playback. Previous literature has pointed out several influencing factors, such as dynamic cues (e.g., h= ead rotation), individualized HRTFs, and headphone equalization.</div> <div><br> </div> <div>However, I am particularly interested in whether it is still possible = to achieve a <b>clear sense of directional perception</b> under <b>static listening cond= itions</b> with <b>non-individualized HRTFs</b>. Specifically, even if precise localization= is not attained, might there be techniques or strategies that allow listen= ers to <b>clearly and reliably </b>distinguish between front and back, as well as = between above and below?<br> <br> Any insights, relevant experiences, or useful references would be greatly a= ppreciated. I would also welcome any discussion or perspectives on this top= ic. <br> <br> Best regards, <br> Dingding Yao<br> </div> </div> </div> </div> </body> </html> --_000_LO0P265MB3035DB22588B51A14B9E83A3BA2CALO0P265MB3035GBRP_--