{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,23]],"date-time":"2025-12-23T15:32:01Z","timestamp":1766503921007,"version":"build-2065373602"},"reference-count":48,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2024,7,17]],"date-time":"2024-07-17T00:00:00Z","timestamp":1721174400000},"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>Eco-acoustic indices allow us to rapidly evaluate habitats and ecosystems and derive information about anthropophonic impacts. However, it is proven that indices\u2019 values and trends are not comparable between studies. These incongruences may be caused by the availability on the market of recorders with different characteristics and costs. Thus, there is a need to reduce these biases and incongruences to ensure an accurate analysis and comparison between soundscape ecology studies and habitat assessments. In this study, we propose and validate an audio recording equalization protocol to reduce eco-acoustic indices\u2019 biases, by testing three soundscape recorder models: Song Meter Micro, Soundscape Explorer Terrestrial and Audiomoth. The equalization process aligns the signal amplitude and frequency response of the soundscape recorders to those of a type 1 level meter. The adjustment was made in MATLAB R2023a using a filter curve generated comparing a reference signal (white noise); the measurements were performed in an anechoic chamber using 11 audio sensors and a type 1 sound level meter (able to produce a .WAV file). The statistical validation of the procedure was performed on recordings obtained in an urban and Regional Park (Italy) assessing a significant reduction in indices\u2019 biases on the Song Meter Micro and Audiomoth.<\/jats:p>","DOI":"10.3390\/s24144642","type":"journal-article","created":{"date-parts":[[2024,7,17]],"date-time":"2024-07-17T15:15:19Z","timestamp":1721229319000},"page":"4642","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Biases in Ecoacoustics Analysis: A Protocol to Equalize Audio Recorders"],"prefix":"10.3390","volume":"24","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3871-694X","authenticated-orcid":false,"given":"Andrea","family":"Potenza","sequence":"first","affiliation":[{"name":"Department of Earth and Environmental Sciences, University of Milano-Bicocca, 20126 Milan, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Valentina","family":"Zaffaroni-Caorsi","sequence":"additional","affiliation":[{"name":"Department of Earth and Environmental Sciences, University of Milano-Bicocca, 20126 Milan, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1195-4542","authenticated-orcid":false,"given":"Roberto","family":"Benocci","sequence":"additional","affiliation":[{"name":"Department of Earth and Environmental Sciences, University of Milano-Bicocca, 20126 Milan, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-3817-7062","authenticated-orcid":false,"given":"Giorgia","family":"Guagliumi","sequence":"additional","affiliation":[{"name":"Department of Earth and Environmental Sciences, University of Milano-Bicocca, 20126 Milan, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5683-9444","authenticated-orcid":false,"given":"Jalal M.","family":"Fouani","sequence":"additional","affiliation":[{"name":"Independent Researcher, 40132 Bologna, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alessandro","family":"Bisceglie","sequence":"additional","affiliation":[{"name":"Department of Earth and Environmental Sciences, University of Milano-Bicocca, 20126 Milan, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2842-7132","authenticated-orcid":false,"given":"Giovanni","family":"Zambon","sequence":"additional","affiliation":[{"name":"Department of Earth and Environmental Sciences, University of Milano-Bicocca, 20126 Milan, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,7,17]]},"reference":[{"key":"ref_1","first-page":"1","article-title":"History of Sound Recording and Analysis Equipment","volume":"Volume 1","author":"Erbe","year":"2022","journal-title":"Exploring Animal Behavior Through Sound"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"20220166","DOI":"10.1515\/noise-2022-0166","article-title":"Framework for Urban Sound Assessment at the City Scale Based on Citizen Action, with the Smartphone Application NoiseCapture as a Lever for Participation","volume":"10","author":"Can","year":"2023","journal-title":"Noise Mapp."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1279","DOI":"10.1121\/1.5052173","article-title":"Assimilation of Mobile Phone Measurements for Noise Mapping of a Neighborhood","volume":"144","author":"Ventura","year":"2018","journal-title":"J. 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