<p class="first" id="d10111809e174">Vocalizations carry emotional, physiological and
individual information. This suggests
that they may serve as potentially useful indicators for inferring animal welfare.
At the same time, automated methods for analysing and classifying sound have developed
rapidly, particularly in the fields of ecology, conservation and sound scene classification.
These methods are already used to automatically classify animal vocalizations, for
example, in identifying animal species and estimating numbers of individuals. Despite
this potential, they have not yet found widespread application in animal welfare monitoring.
In this review, we first discuss current trends in sound analysis for ecology, conservation
and sound classification. Following this, we detail the vocalizations produced by
three of the most important farm livestock species: chickens (
<i>Gallus gallus domesticus</i>), pigs (
<i>Sus scrofa domesticus</i>) and cattle (
<i>Bos taurus</i>). Finally, we describe how these methods can be applied to monitor
with new potential for developing automated methods for large-scale farming.