Bioacoustic variation in Wren Troglodytes troglodytes populations on Welsh islands

BASSA: New software tool reveals hidden details in visualisation of low‐frequency animal sounds

“…Animal sounds, however, are rarely if ever, steady state. They often feature complex spectral and temporal structures, with multiple overlapping tones fluctuating in frequency and amplitude over time (Baotic et al., 2014 ; Cazau et al., 2016 ; Gonzalo‐Tarodo et al., 2020 ; Hedwig et al., 2021 ; Leroy et al., 2021 ; Zhang et al., 2017 ). Effective visualisations of animal sounds, therefore, must illustrate the amount of acoustic energy, where that energy occurs in the frequency spectrum and when it occurs in time.…”

“…The STFT was first used to study animal sounds in 1971 (Coutlee, 1971 ), and has since become a ubiquitous feature of research in bioacoustics (Baotic et al., 2014 ; Boucher et al., 2020 ; Bussmann et al., 2021 ; Cazau et al., 2016 ; Davenport et al., 2022 ; Dutour et al., 2021 ; Gonzalo‐Tarodo et al., 2020 ; Jégh‐Czinege et al., 2020 ; Leroy et al., 2021 ; Malige et al., 2020 ; Mann et al., 2021 ; McDonald et al., 2009 ; Odom et al., 2021 ; Stoeger et al., 2014 ; Teixeira et al., 2022 ; Thode et al., 2017 ); however, the TF bias is rarely discussed in the bioacoustics literature. TF analysis is used widely in engineering, where it is generally acknowledged that this bias imposes a limit on the STFT spectrogram's accuracy when applied to complex signals, especially at low frequencies.…”

“…Many of these fields have adopted other methods. While there has been at least one study highlighting the issues with the STFT spectrogram in the study of animal sounds (Brumm et al., 2017 ), this remains the most common method in the biological sciences (Baotic et al., 2014 ; Benko & Perc, 2009 ; Bonnefond et al., 2020 ; Bussmann et al., 2021 ; Cazau et al., 2016 ; Davenport et al., 2022 ; Dutour et al., 2021 ; Forti et al., 2017 ; Gonzalo‐Tarodo et al., 2020 ; Jégh‐Czinege et al., 2020 ; Leroy et al., 2021 ; Malige et al., 2020 ; Mann et al., 2021 ; Maruska & Mensinger, 2009 ; McDonald et al., 2009 ; Nelson et al., 2011 ; Odom et al., 2021 ; Rice & Bass, 2009 ; Salas et al., 2018 ; Staniewicz et al., 2023 ; Stoeger et al., 2014 ; Sueur et al., 2011 ; Teixeira et al., 2022 ; Thode et al., 2017 ).…”