{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:23:49Z","timestamp":1760235829969,"version":"build-2065373602"},"reference-count":59,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2021,9,28]],"date-time":"2021-09-28T00:00:00Z","timestamp":1632787200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Background: Clinically valid and reliable simulated inspiratory sounds were required for the development and evaluation of a new therapeutic respiratory exergame application (i.e., QUT Inspire). This smartphone application virtualises incentive spirometry, a longstanding respiratory therapy technique. Objectives: Inspiratory flows were simulated using a 3 litre calibration syringe and validated using clinical reference devices. Syringe flow nozzles of decreasing diameter were applied to model the influence of mouth shape on audible sound levels generated. Methods: A library of calibrated audio inspiratory sounds was created to determine the reliability and range of inspiratory sound detection at increasing distances separating the sound source and smartphones running the app. Results: Simulated inspiratory sounds were reliably detected by the new application at higher air inflows (high, medium), using smaller mouth diameters (&lt;25 mm) and where smartphones were held proximal (\u22645 cm) to the mouth (or at distances up to 50 cm for higher airflows). Performance was comparable for popular smartphone types and using different phone orientations (i.e., held horizontally, at 45\u00b0 or 90\u00b0). Conclusions: These observations inform future application refinements, including prompts to reduce mouth diameter, increase inspiratory flow and maintain proximity to the phone to optimise sound detection. This library of calibrated inspiratory sounds offers reproducible non-human reference data suitable for development, evaluation and regression testing of a therapeutic respiratory exergame application for smartphones.<\/jats:p>","DOI":"10.3390\/s21196472","type":"journal-article","created":{"date-parts":[[2021,9,28]],"date-time":"2021-09-28T21:39:29Z","timestamp":1632865169000},"page":"6472","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Seeking Inspiration: Examining the Validity and Reliability of a New Smartphone Respiratory Therapy Exergame App"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8258-4836","authenticated-orcid":false,"given":"Clarence","family":"Baxter","sequence":"first","affiliation":[{"name":"School of Public Health and Social Work, Faculty of Health, Queensland University of Technology, Kelvin Grove 4059, Australia"},{"name":"School of Public Health and Social Work, Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove 4059, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0770-6527","authenticated-orcid":false,"given":"Julie-Anne","family":"Carroll","sequence":"additional","affiliation":[{"name":"School of Public Health and Social Work, Faculty of Health, Queensland University of Technology, Kelvin Grove 4059, Australia"},{"name":"School of Public Health and Social Work, Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove 4059, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4565-4641","authenticated-orcid":false,"given":"Brendan","family":"Keogh","sequence":"additional","affiliation":[{"name":"Digital Media Research Centre, Creative Industries, Education, and Social Justice Faculty, Queensland University of Technology, Kelvin Grove 4059, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4445-8094","authenticated-orcid":false,"given":"Corneel","family":"Vandelanotte","sequence":"additional","affiliation":[{"name":"Physical Activity Research Group, Appleton Institute, Central Queensland University, Rockhampton 4702, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1054","DOI":"10.1016\/j.chaos.2005.08.197","article-title":"Chaotic dynamics of respiratory sounds","volume":"29","author":"Ahlstrom","year":"2006","journal-title":"Chaos Solitons Fractals"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Islam, M.S., Paul, G., Ong, H.X., Young, P.M., Gu, Y.T., and Saha, S.C. 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