Comparison between android applications and Class-I sound level meters in SPL measurement performance

Accurate measurement of sound pressure level (SPL) is a cornerstone for understanding acoustic communication, animal behavior, and ecological dynamics. Acoustic signals can be broadly categorized into broadband and tonal sounds. Broadband noise – spanning a wide frequency range – is useful for assessing general noise levels, while tonal sounds, defined by distinct harmonic frequencies, provide critical insight into subtle phenomena such as animal communication, echolocation, and specific patterns of noise pollution. Smartphone-based SPL measurement has emerged as an accessible and cost-effective alternative to conventional sound level meters (SLMs). However, previous evaluations of SPL applications have primarily relied on iOS platforms and broadband noise measurements, leaving a significant gap in understanding how these tools perform for tonal sound measurements on Android devices – the more widely used operating system. To address these limitations, our study evaluated top three freely available Android SPL applications – Bolden, Kewlsoft, and KTW – against a Brüel & Kjær Class I SLM. The assessment employed both white noise and tonal stimuli across frequencies representative of natural soundscapes, facilitating a comprehensive performance comparison. Among these, the Bolden Sound Level Meter consistently delivered the most accurate readings for tonal measurements, whereas KTW performed well for broadband noise measurement, demonstrating the potential of Android-based tools in advancing environmental monitoring and wildlife conservation initiatives.