Characterizing Sounds under Commercial Broiler Environment

Abstract

<b><sc>Abstract.</sc></b> Audio data collected in commercial broiler houses are mixed sounds of different sources, which contains useful information regarding bird health condition, bird behavior, and equipment operation. However, characterizations of the sounds of different sources in commercial broiler houses have not been well established. The objective of this study was, therefore, to determine the frequency ranges of six common sounds, including bird vocalization, fan, feeder operation, heater, wing flapping, and dustbathing, at bird ages of week 1 to 8 in a commercial broiler house. In addition, the frequencies of flapping (in wing flapping events, flaps/sec) and scratching (during dustbathing, scratches/sec) behaviors were examined through sound analysis. A microphone was installed in the middle of broiler house at the height of 40 cm above the back of birds to record audio data at a sampling frequency of 44100 Hz. A top-view camera was installed to continuously monitor bird activities. Total of 85-min audio data were manually labelled and fed to MATLAB for analysis. The audio data were decomposed using Maximum Overlap Discrete Wavelet Transform (MODWT). Decompositions of the six concerned sound sources were then transformed with Fast Fourier Transform (FFT) method to generate the single-sided amplitude spectrums. By fitting the amplitude spectrum of each sound source into a Gaussian regression model, its frequency range was determined as the span of the two standard deviations (95% CI) away from the mean. The behavioral frequencies were determined by examining the spectrograms of wing flapping and dustbathing sounds. They were calculated by dividing the number of movements by the time duration of complete behavioral events. The frequency ranges of bird vocalization changed from 2481±191-4409±136 Hz to 1058±123-2501±88 Hz as birds grew. For the sound of fan, the frequency range was 0-1746±38 Hz. The frequencies of feeder operation sound ranged from 129±36-1141±50 Hz to 454±86-1449±75 Hz. As for heater, wing flapping and dustbathing, the sound frequencies varied from 0 Hz to over 19000 Hz. The behavioral frequencies of wing flapping and dustbathing were all decreased from week 3 (17±4 flaps/sec and 16±2 scratches/sec) to week 8 (10±1 flaps/sec and 11±3 scratches/sec). In conclusion, characterizing sounds of different sound sources in commercial broiler houses provides useful information for further advanced acoustic analysis that may assists farm management and continuous monitoring of animal health and behavior.