Guillaume Dutilleux | Searcharxiv

arXiv2024

Unattended field measurement of bird source level

Sound power levels or so-called source levels are essential quantities when it comes to evaluating the active space of bird species, both in the study of animal communication and when designing bioacoustic monitoring schemes. However, little data is available in the literature. In this paper I demonstrate the feasibility of the measurement of apparent sound power in the field for bird species by using a calibrated 4-microphone horizontal array deployed on the ground. Time differences of arrival allow for the location of the sound source. Assuming a point source, the apparent sound power level is estimated after correcting for ground reflection and spherical divergence but cannot be corrected for source directivity. The benefits of my approach that is inspired from engineering measurement standards for elevated sound sources, is to minimize the contribution from ground reflections and to allow for unattended measurements, or measurements when the bird is not visible, owing to either foliage or obscurity. Moreover, my paper brings new data on sound power for 4 species of birds.

physics.app-ph↗

arXiv2023

Sound emergence as a predictor of short-term annoyance from wind turbine noise

While sound emergence is used in several countries to regulate wind energy development, there is no published evidence that it is a relevant noise descriptor for this purpose. In the present work, we carried out two listening tests to evaluate the merits of sound emergence. Three definitions of sound emergence were considered: the one in ISO 1996-1, sound emergence under audibility condition $e_{UAC}$, and spectral emergence $e_{SP}$. We also considered the specific to residual ratio and loudness metrics. In each listening test, the sound stimuli consisted of 48 sound stimuli at 3 A-weighted sound pressure levels $\{30, 40, 50\}$~dB and 4 specific-to-residual ratios $\{-10, -5, 0, +5 \}$~dB. The results lead to the conclusion that short term annoyance is better predicted by the total sound pressure level than by sound emergence, whatever the definition considered for the latter, or than by the specific to residual ratio. Short-term annoyance is slightly better predicted by $e_{UAC}$ than by $e$, while $e$ is a better predictor than $e_{SP}$. The total sound pressure level and the loudness metrics performed similarly. Furthermore, the results provide evidence that sound emergence is a poor predictor of the audibility of wind turbine sounds.

eess.AS↗