The researchers say the sounds pigs make express their emotions and farmers could automatically collect their sounds and make adjustments to improve their welfare.
In order to build this tool, the researchers started by collecting thousands of vocalisations. In the end, over 7,400 good quality vocalisations from 411 pigs in different European laboratories could be analysed.
These sounds were recorded in 19 different contexts: from the birth of the pigs and throughout their life, in different types of indoor rearing (e.g. on slatted floors or on straw) and in slaughterhouses.
These contexts can be sources of positive emotions, such as suckling and reunion with fellow pigs or negative ones, such as fights and isolation.
By combining the expertise of ethologists, bioacousticians for the detailed analysis of the acoustic structure of the recorded vocalisations and computational methods of artificial intelligence, the researchers worked on the automatic classification of the vocalisations according to negative and positive emotions and the situation in which they were emitted, with a view to possible action by the livestock farmer.
The results show that artificial intelligence is very effective at recognising not only the emotional valence of the vocalisations (91.5 per cent accuracy), but also the situation in which they were emitted (82 per cebt accuracy).
On receiving a new sound, the system will automatically compare it with previously classified sounds to qualify it.
The researchers say this system could be of great help to livestock farmers as it could alert them in real time if a situation requires their immediate intervention, such as in the case of a piglet being crushed by the mother or repeated or prolonged fights within a group.
It would also allow livestock farmers to reinforce positive situations for the pigs, helping them to evaluate, for example, the provision of new toys or infrastructure to enhance the welfare of their animals.
Similar acoustic monitoring systems already exist on farms to monitor the health of pigs by analysing the noise of their coughs. The research team is now working on adding an analysis of pig vocalisations to this listening system in order to combine physical and mental health measures for better welfare on-farm.