{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,14]],"date-time":"2026-06-14T08:19:04Z","timestamp":1781425144539,"version":"3.54.1"},"update-to":[{"DOI":"10.1371\/journal.pcbi.1008744","type":"new_version","label":"New version","source":"publisher","updated":{"date-parts":[[2021,4,8]],"date-time":"2021-04-08T00:00:00Z","timestamp":1617840000000}}],"reference-count":59,"publisher":"Public Library of Science (PLoS)","issue":"3","license":[{"start":{"date-parts":[[2021,3,29]],"date-time":"2021-03-29T00:00:00Z","timestamp":1616976000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000055","name":"National Institute on Deafness and Other Communication Disorders","doi-asserted-by":"publisher","award":["DC013573"],"award-info":[{"award-number":["DC013573"]}],"id":[{"id":"10.13039\/100000055","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.ploscompbiol.org"],"crossmark-restriction":false},"short-container-title":["PLoS Comput Biol"],"abstract":"<jats:p>Vocalization in mammals, birds, reptiles, and amphibians occurs with airways that have wide openings to free-space for efficient sound radiation, but sound is also produced with occluded or semi-occluded airways that have small openings to free-space. It is hypothesized that pressures produced inside the airway with semi-occluded vocalizations have an overall widening effect on the airway. This overall widening then provides more opportunity to produce wide-narrow contrasts along the airway for variation in sound quality and loudness. For human vocalization described here, special emphasis is placed on the epilaryngeal airway, which can be adjusted for optimal aerodynamic power transfer and for optimal acoustic source-airway interaction. The methodology is three-fold, (1) geometric measurement of airway dimensions from CT scans, (2) aerodynamic and acoustic impedance calculation of the airways, and (3) simulation of acoustic signals with a self-oscillating computational model of the sound source and wave propagation.<\/jats:p>","DOI":"10.1371\/journal.pcbi.1008744","type":"journal-article","created":{"date-parts":[[2021,3,29]],"date-time":"2021-03-29T17:37:01Z","timestamp":1617039421000},"page":"e1008744","update-policy":"https:\/\/doi.org\/10.1371\/journal.pcbi.corrections_policy","source":"Crossref","is-referenced-by-count":26,"title":["Vocalization with semi-occluded airways is favorable for optimizing sound production"],"prefix":"10.1371","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0148-0750","authenticated-orcid":true,"given":"Ingo R.","family":"Titze","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4273-9113","authenticated-orcid":true,"given":"Anil","family":"Palaparthi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4932-4527","authenticated-orcid":true,"given":"Karin","family":"Cox","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amanda","family":"Stark","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lynn","family":"Maxfield","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2875-5005","authenticated-orcid":true,"given":"Brian","family":"Manternach","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2021,3,29]]},"reference":[{"issue":"5","key":"pcbi.1008744.ref001","doi-asserted-by":"crossref","first-page":"2895","DOI":"10.1121\/1.2897001","article-title":"The structure of vocal sounds produced with the mouth closed or with the mouth open in treefrogs","volume":"123","author":"M. Gridi-Papp","year":"2008","journal-title":"The Journal of the Acoustical Society of America"},{"issue":"1","key":"pcbi.1008744.ref002","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1134\/S0012496614020094","article-title":"Vocalization with the mouth closed as a mechanism of generation of the low-frequency sound signal in great gerbil (mammalia, Rodentia)","volume":"455","author":"A. Nikol\u2019skii","year":"2014","journal-title":"InDoklady Biological Sciences"},{"issue":"8","key":"pcbi.1008744.ref003","doi-asserted-by":"crossref","first-page":"1734","DOI":"10.1111\/evo.12988","article-title":"Coos, booms, and hoots: The evolution of closed-mouth vocal behavior in birds","volume":"70","author":"T Riede","year":"2016","journal-title":"Evolution"},{"issue":"6","key":"pcbi.1008744.ref004","doi-asserted-by":"crossref","first-page":"1072","DOI":"10.1644\/06-MAMM-A-079R2.1","article-title":"North American elk bugle vocalizations: male and female bugle call structure and context","volume":"87","author":"J Feighny","year":"2006","journal-title":"Journal of Mammalogy"},{"issue":"4","key":"pcbi.1008744.ref005","doi-asserted-by":"crossref","first-page":"847","DOI":"10.2307\/1379656","article-title":"Long-distance vocalizations of coyotes (Canis latrans)","volume":"56","author":"H. McCarley","year":"1975","journal-title":"Journal of Mammalogy"},{"issue":"4","key":"pcbi.1008744.ref006","doi-asserted-by":"crossref","first-page":"735","DOI":"10.1006\/anbe.1993.1088","article-title":"Contexts and social correlates of long-distance calling by male chimpanzees","volume":"45","author":"J Mitani","year":"1993","journal-title":"Animal Behaviour"},{"issue":"1","key":"pcbi.1008744.ref007","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1163\/156853982X00517","article-title":"The function of howling in red howler monkeys (Alouatta seniculus)","volume":"81","author":"R. Sekulic","year":"1982","journal-title":"Behaviour"},{"issue":"2","key":"pcbi.1008744.ref008","doi-asserted-by":"crossref","first-page":"331","DOI":"10.1093\/icb\/7.2.331","article-title":"Howling as a means of communication in timber wolves","volume":"7","author":"J Theberge","year":"1967","journal-title":"American Zoologist"},{"issue":"5","key":"pcbi.1008744.ref009","doi-asserted-by":"crossref","first-page":"2813","DOI":"10.1121\/1.5034768","article-title":"Radiation efficiency for long-range vocal communication in mammals and birds","volume":"143","author":"I Titze","year":"2018","journal-title":"The Journal of the Acoustical Society of America"},{"issue":"1","key":"pcbi.1008744.ref010","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1007\/BF02700156","article-title":"Vox Alouattinae: a preliminary survey of the acoustic characteristics of long-distance calls of howling monkeys","volume":"16","author":"J. Whitehead","year":"1995","journal-title":"International Journal of Primatology"},{"issue":"6","key":"pcbi.1008744.ref011","doi-asserted-by":"crossref","first-page":"477","DOI":"10.1046\/j.1439-0310.1999.00396.x","article-title":"The predator deterrence function of primate alarm calls.","volume":"105","author":"K Zuberb\u00fchler","year":"1999","journal-title":"Ethology"},{"key":"pcbi.1008744.ref012","volume-title":"The Oxford companion to musical instruments","author":"A Baines","year":"1992"},{"issue":"2","key":"pcbi.1008744.ref013","doi-asserted-by":"crossref","first-page":"e2006507","DOI":"10.1371\/journal.pbio.2006507","article-title":"The evolution of the syrinx: An acoustic theory","volume":"17","author":"T Riede","year":"2019","journal-title":"PLoS biology"},{"issue":"2","key":"pcbi.1008744.ref014","doi-asserted-by":"crossref","first-page":"1200","DOI":"10.1121\/1.414601","article-title":"Trumpet sound simulation using a two-dimensional lip vibration model","volume":"99","author":"S Adachi","year":"1996","journal-title":"The Journal of the Acoustical Society of America"},{"key":"pcbi.1008744.ref015","article-title":"Vocology: The science and practice of voice habilitation","author":"I Titze","year":"2012","journal-title":"National Center for Voice and Speech"},{"issue":"6","key":"pcbi.1008744.ref016","first-page":"814","article-title":"Vocal exercise may attenuate acute vocal fold inflammation","volume":"26","author":"K Abbott","year":"2012","journal-title":"Journal of Voice"},{"issue":"3","key":"pcbi.1008744.ref017","doi-asserted-by":"crossref","first-page":"535","DOI":"10.1044\/2015_JSLHR-S-13-0231","article-title":"A randomized controlled trial of two semi-occluded vocal tract voice therapy protocols.","volume":"58","author":"M Kapsner-Smith","year":"2015","journal-title":"Journal of Speech, Language, and Hearing Research"},{"issue":"3","key":"pcbi.1008744.ref018","doi-asserted-by":"crossref","first-page":"271","DOI":"10.1016\/S0892-1997(05)80299-1","article-title":"Efficacy of vocal function exercises as a method of improving voice production","volume":"8","author":"J Stemple","year":"1994","journal-title":"Journal of voice"},{"issue":"1","key":"pcbi.1008744.ref019","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1109\/TAU.1968.1161949","article-title":"Self-oscillating source for vocal-tract synthesizers","volume":"16","author":"J Flanagan","year":"1968","journal-title":"IEEE Transactions on Audio and Electroacoustics"},{"issue":"6","key":"pcbi.1008744.ref020","doi-asserted-by":"crossref","first-page":"1233","DOI":"10.1002\/j.1538-7305.1972.tb02651.x","article-title":"Synthesis of voiced sounds from a two-mass model of the vocal cords","volume":"51","author":"K Ishizaka","year":"1972","journal-title":"Bell system technical journal"},{"key":"pcbi.1008744.ref021","doi-asserted-by":"crossref","DOI":"10.1093\/oso\/9780195069402.001.0001","volume-title":"Acoustic systems in biology","author":"N. Fletcher","year":"1992"},{"issue":"4","key":"pcbi.1008744.ref022","doi-asserted-by":"crossref","first-page":"1536","DOI":"10.1121\/1.395910","article-title":"The physics of small-amplitude oscillation of the vocal folds","volume":"83","author":"I. Titze","year":"1988","journal-title":"The Journal of the Acoustical Society of America"},{"issue":"3\u20134","key":"pcbi.1008744.ref023","first-page":"167","article-title":"Calculation of true glottal flow and its components. Speech Communication","volume":"1","author":"T Ananthapadmanabha","year":"1982","journal-title":"Dec 1"},{"issue":"3\u20134","key":"pcbi.1008744.ref024","doi-asserted-by":"crossref","first-page":"393","DOI":"10.1016\/S0095-4470(19)30714-4","article-title":"Glottal flow: models and interaction","volume":"14","author":"G. Fant","year":"1986","journal-title":"Journal of Phonetics"},{"key":"pcbi.1008744.ref025","first-page":"305","article-title":"Acoustic interaction between the glottal source and the vocal tract","volume":"1","author":"M. Rothenberg","year":"1981","journal-title":"Vocal fold physiology"},{"issue":"4","key":"pcbi.1008744.ref026","first-page":"641","article-title":"Theory of glottal airflow and source-filter interaction in speaking and singing","volume":"90","author":"I. Titze","year":"2004","journal-title":"Acta Acustica united with Acustica"},{"issue":"6","key":"pcbi.1008744.ref027","doi-asserted-by":"crossref","first-page":"3722","DOI":"10.1121\/1.418331","article-title":"Further studies of phonation threshold pressure in a physical model of the vocal fold mucosa","volume":"101","author":"R Chan","year":"1997","journal-title":"The Journal of the Acoustical Society of America"},{"key":"pcbi.1008744.ref028","volume-title":"Acoustic theory of speech production","author":"G. Fant","year":"1970"},{"issue":"5","key":"pcbi.1008744.ref029","doi-asserted-by":"crossref","first-page":"611","DOI":"10.1007\/s10162-013-0407-y","article-title":"An analysis of the acoustic input impedance of the ear","volume":"14","author":"R Withnell","year":"2013","journal-title":"Journal of the Association for Research in Otolaryngology"},{"issue":"1","key":"pcbi.1008744.ref030","first-page":"50","article-title":"The effect of phonation into a straw on the vocal tract adjustments and formant frequencies. A preliminary MRI study on a single subject completed with acoustic results. Biomedical Signal Processing and Control","volume":"7","author":"A Laukkanen","year":"2012","journal-title":"Jan 1"},{"issue":"6","key":"pcbi.1008744.ref031","doi-asserted-by":"crossref","first-page":"709","DOI":"10.1016\/j.jvoice.2013.05.007","article-title":"Laryngeal and pharyngeal activity during semioccluded vocal tract postures in subjects diagnosed with hyperfunctional dysphonia","volume":"27","author":"M Guzman","year":"2013","journal-title":"Journal of Voice"},{"issue":"2","key":"pcbi.1008744.ref032","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1159\/000437353","article-title":"Do different semi-occluded voice exercises affect vocal fold adduction differently in subjects diagnosed with hyperfunctional dysphonia?.","volume":"67","author":"M Guzman","year":"2015","journal-title":"Folia phoniatrica et logopaedica"},{"issue":"1","key":"pcbi.1008744.ref033","doi-asserted-by":"crossref","first-page":"537","DOI":"10.1121\/1.415960","article-title":"Vocal tract area functions from magnetic resonance imaging","volume":"100","author":"B Story","year":"1996","journal-title":"The Journal of the Acoustical Society of America"},{"issue":"1","key":"pcbi.1008744.ref034","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1016\/S0892-1997(05)80114-6","article-title":"A critical view of the yawn-sigh as a voice therapy technique","volume":"7","author":"D Boone","year":"1993","journal-title":"Journal of Voice"},{"issue":"3","key":"pcbi.1008744.ref035","doi-asserted-by":"crossref","first-page":"377","DOI":"10.1016\/j.jvoice.2015.05.006","article-title":"Semioccluded vocal tract exercises: changes in laryngeal and pharyngeal activity during stroboscopy","volume":"30","author":"T Dargin","year":"2016","journal-title":"Journal of Voice"},{"issue":"2","key":"pcbi.1008744.ref036","doi-asserted-by":"crossref","first-page":"219","DOI":"10.1016\/S0892-1997(99)80024-1","article-title":"Preliminary study on the ability of trained singers to control the intrinsic and extrinsic laryngeal musculature","volume":"13","author":"J Lovetri","year":"1999","journal-title":"Journal of Voice"},{"issue":"2","key":"pcbi.1008744.ref037","doi-asserted-by":"crossref","first-page":"86","DOI":"10.3109\/14015439.2014.913074","article-title":"Intraoral pressures produced by thirteen semi-occluded vocal tract gestures.","volume":"40","author":"L Maxfield","year":"2015","journal-title":"Logopedics Phoniatrics Vocology"},{"key":"pcbi.1008744.ref038","article-title":"Voice training and therapy with a semi-occluded vocal tract: rationale and scientific underpinnings.","author":"I. Titze","year":"2006","journal-title":"Journal of Speech, Language, and Hearing Research"},{"issue":"5","key":"pcbi.1008744.ref039","doi-asserted-by":"crossref","first-page":"589","DOI":"10.1016\/j.jvoice.2013.11.004","article-title":"Electroglottographic study of seven semi-occluded exercises: LaxVox, straw, lip-trill, tongue-trill, humming, hand-over-mouth, and tongue-trill combined with hand-over-mouth","volume":"28","author":"P Andrade","year":"2014","journal-title":"Journal of Voice"},{"issue":"4","key":"pcbi.1008744.ref040","doi-asserted-by":"crossref","first-page":"582","DOI":"10.1016\/j.jvoice.2019.01.007","article-title":"Variation on vocal economy after different semioccluded vocal tract exercises in subjects with normal voice and dysphonia","volume":"34","author":"C Calvache","year":"2020","journal-title":"Journal of Voice"},{"issue":"2","key":"pcbi.1008744.ref041","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1016\/j.jvoice.2016.08.009","article-title":"Immediate effects of the vocal function exercises semi-occluded mouth posture on glottal airflow parameters: A preliminary study","volume":"31","author":"D Croake","year":"2017","journal-title":"Journal of Voice"},{"issue":"9","key":"pcbi.1008744.ref042","doi-asserted-by":"crossref","first-page":"2519","DOI":"10.1044\/2017_JSLHR-S-17-0017","article-title":"Short-term effect of two semi-occluded vocal tract training programs on the vocal quality of future occupational voice users:\u201cResonant Voice Training Using Nasal Consonants\u201d Versus \u201cStraw Phonation\u201d","volume":"60","author":"I Meerschman","year":"2017","journal-title":"Journal of Speech, Language, and Hearing Research"},{"issue":"3","key":"pcbi.1008744.ref043","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1016\/j.jvoice.2016.04.009","article-title":"Validation and evaluation of the effects of semi-occluded face mask straw phonation therapy methods on aerodynamic parameters in comparison to traditional methods","volume":"31","author":"R Mills","year":"2017","journal-title":"Journal of Voice"},{"issue":"4","key":"pcbi.1008744.ref044","doi-asserted-by":"crossref","first-page":"455","DOI":"10.1016\/S0892-1997(00)80003-X","article-title":"Acoustic impedance of an artificially lengthened and constricted vocal tract","volume":"14","author":"B Story","year":"2000","journal-title":"Journal of Voice"},{"issue":"4","key":"pcbi.1008744.ref045","doi-asserted-by":"crossref","first-page":"1902","DOI":"10.1121\/1.2832339","article-title":"Nonlinear source\u2013filter coupling in phonation: Theory","volume":"123","author":"I. Titze","year":"2008","journal-title":"The Journal of the Acoustical Society of America"},{"issue":"6","key":"pcbi.1008744.ref046","doi-asserted-by":"crossref","first-page":"3249","DOI":"10.1121\/1.4900563","article-title":"Benchmarks for time-domain simulation of sound propagation in soft-walled airways: steady configurations","volume":"136","author":"I Titze","year":"2014","journal-title":"The Journal of the Acoustical Society of America"},{"issue":"12","key":"pcbi.1008744.ref047","doi-asserted-by":"crossref","first-page":"2507","DOI":"10.1109\/TASLP.2016.2616543","article-title":"Sensitivity of source\u2013filter interaction to specific vocal tract shapes","volume":"24","author":"I Titze","year":"2016","journal-title":"IEEE\/ACM Transactions on Audio, Speech, and Language Processing"},{"issue":"1","key":"pcbi.1008744.ref048","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1016\/j.jvoice.2018.08.014","article-title":"Feature maps of the acoustic spectrum of the voice","volume":"34","author":"P Pabon","year":"2020","journal-title":"Journal of Voice"},{"issue":"3","key":"pcbi.1008744.ref049","doi-asserted-by":"crossref","first-page":"1689","DOI":"10.1121\/1.2000787","article-title":"Aerodynamic transfer of energy to the vocal folds","volume":"118","author":"S Thomson","year":"2005","journal-title":"The Journal of the Acoustical Society of America"},{"issue":"3","key":"pcbi.1008744.ref050","doi-asserted-by":"crossref","first-page":"1597","DOI":"10.1121\/1.3605672","article-title":"Phonation threshold pressure: Comparison of calculations and measurements taken with physical models of the vocal fold mucosa","volume":"130","author":"L Fulcher","year":"2011","journal-title":"The Journal of the Acoustical Society of America"},{"issue":"6","key":"pcbi.1008744.ref051","doi-asserted-by":"crossref","first-page":"773","DOI":"10.1016\/j.jvoice.2017.02.016","article-title":"Whisper and phonation: Aerodynamic comparisons across adduction and loudness","volume":"31","author":"R Konnai","year":"2017","journal-title":"Journal of Voice"},{"issue":"8","key":"pcbi.1008744.ref052","doi-asserted-by":"crossref","first-page":"2589","DOI":"10.1044\/2020_JSLHR-20-00060","article-title":"Inertagrams for a Variety of Semi-Occluded Vocal Tracts","volume":"63","author":"I. Titze","year":"2020","journal-title":"Journal of Speech, Language, and Hearing Research"},{"issue":"1","key":"pcbi.1008744.ref053","doi-asserted-by":"crossref","first-page":"124","DOI":"10.1016\/j.jvoice.2016.01.003","article-title":"Computerized tomography measures during and after artificial lengthening of the vocal tract in subjects with voice disorders","volume":"31","author":"M Guzman","year":"2017","journal-title":"Journal of voice"},{"issue":"3","key":"pcbi.1008744.ref054","doi-asserted-by":"crossref","first-page":"296","DOI":"10.1109\/13.406510","article-title":"A general maximum power transfer theorem","volume":"38","author":"C. Kong","year":"1995","journal-title":"IEEE Transactions on Education"},{"key":"pcbi.1008744.ref055","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1007\/978-3-030-28852-5_2","volume-title":"Neurologic and Neurodegenerative Diseases of the Larynx","author":"S Khosla","year":"2020"},{"issue":"3","key":"pcbi.1008744.ref056","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1177\/000348940711600310","article-title":"Vortical flow field during phonation in an excised canine larynx model","volume":"116","author":"S Khosla","year":"2007","journal-title":"Annals of Otology, Rhinology & Laryngology"},{"issue":"6","key":"pcbi.1008744.ref057","doi-asserted-by":"crossref","first-page":"3416","DOI":"10.1121\/1.411449","article-title":"Theoretical and experimental study of quasisteady-flow separation within the glottis during phonation. Application to a modified two-mass model","volume":"96","author":"X Pelorson","year":"1994","journal-title":"The Journal of the Acoustical Society of America"},{"issue":"1","key":"pcbi.1008744.ref058","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1016\/j.jvoice.2016.04.001","article-title":"Characterization of flow-resistant tubes used for semi-occluded vocal tract voice training and therapy","volume":"31","author":"S Smith","year":"2017","journal-title":"Journal of Voice"},{"issue":"6","key":"pcbi.1008744.ref059","doi-asserted-by":"crossref","first-page":"2207","DOI":"10.1152\/jappl.1999.87.6.2207","article-title":"A three-dimensional model of the human airway tree","volume":"87","author":"H Kitaoka","year":"1999","journal-title":"Journal of Applied Physiology"}],"updated-by":[{"DOI":"10.1371\/journal.pcbi.1008744","type":"new_version","label":"New version","source":"publisher","updated":{"date-parts":[[2021,4,8]],"date-time":"2021-04-08T00:00:00Z","timestamp":1617840000000}}],"container-title":["PLOS Computational Biology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pcbi.1008744","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,8,27]],"date-time":"2024-08-27T01:58:27Z","timestamp":1724723907000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pcbi.1008744"}},"subtitle":[],"editor":[{"given":"Alison","family":"Marsden","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2021,3,29]]},"references-count":59,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2021,3,29]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pcbi.1008744","relation":{"new_version":[{"id-type":"doi","id":"10.1371\/journal.pcbi.1008744","asserted-by":"object"}]},"ISSN":["1553-7358"],"issn-type":[{"value":"1553-7358","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,3,29]]}}}