{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T14:12:14Z","timestamp":1789135934008,"version":"build-2803163510"},"reference-count":42,"publisher":"Acoustical Society of America (ASA)","issue":"3","license":[{"start":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T00:00:00Z","timestamp":1789084800000},"content-version":"vor","delay-in-days":10,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["DFG WE 4057\/21-1"],"award-info":[{"award-number":["DFG WE 4057\/21-1"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2026,9,1]]},"abstract":"<jats:p>Source directivity is an integral part of room acoustic simulation, affecting not only the intensity and frequency balance of the direct sound depending on source orientation, but also room-acoustic parameters, such as the direct-to-reverberant energy ratio. While the directivity of a loudspeaker is time-invariant, the directivity of other sound sources, such as the human voice, varies over time. Whether these time-dependent directivity changes must be fully considered for a plausible binaural rendering of speech remains an open question, requiring rendering solutions that can reproduce time-varying directivity. This work provides three key contributions. First, it introduces a feature for liveRAZR\u2014a real-time, six-degrees-of-freedom room acoustic simulator\u2014to render sound sources with time-varying directivity from Ambisonics input. Second, it proposes a method to generate speech material with time-varying directivity from monaural recordings using phoneme-dependent directivity filters. Third, it presents a listening experiment comparing fluent speech with multiple time-varying and static directivities regarding transfer-plausibility and perceptual qualities. Time-varying directivity did not significantly improve transfer-plausibility or liveliness and source-orientation clarity ratings compared to static, measurement-based directivity in the tested scenario. However, analytically obtained spherical head model directivity reduced these perceptual qualities, indicating that measurement-based voice directivity is preferable for demanding immersive extended reality applications.<\/jats:p>","DOI":"10.1121\/10.0046466","type":"journal-article","created":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T13:57:43Z","timestamp":1789135063000},"page":"2223-2236","update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Time-varying voice directivity in real-time room acoustic simulation: Implementation and perceptual evaluation"],"prefix":"10.1121","volume":"160","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-0599-6918","authenticated-orcid":false,"given":"Johannes F.","family":"Sommerfeldt","sequence":"first","affiliation":[{"name":"Audio Communication Group, Technische Universit\u00e4t Berlin 1 , Berlin,","place":["Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1905-1361","authenticated-orcid":false,"given":"Fabian","family":"Brinkmann","sequence":"additional","affiliation":[{"name":"Audio Communication Group, Technische Universit\u00e4t Berlin 1 , Berlin,","place":["Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9427-9932","authenticated-orcid":false,"given":"Stefan","family":"Weinzierl","sequence":"additional","affiliation":[{"name":"Audio Communication Group, Technische Universit\u00e4t Berlin 1 , Berlin,","place":["Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5403-4076","authenticated-orcid":false,"given":"Johannes M.","family":"Arend","sequence":"additional","affiliation":[{"name":"Acoustics Lab, Department of Information and Communications Engineering, Aalto University 2 , Espoo,","place":["Finland"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"231","published-online":{"date-parts":[[2026,9,11]]},"reference":[{"issue":"4","key":"2026091109573620600_c1","doi-asserted-by":"publisher","first-page":"2302","DOI":"10.1121\/10.0025463","article-title":"Musical instruments as dynamic sound sources","volume":"155","year":"2024","journal-title":"J. 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