A study published earlier this month by the University of Copenhagen, ETH Zurich and the French National Research Institute for Agriculture, Food and Environment claims to have decoded the emotions of pigs by analyzing their sounds.

The researchers captured for analysis 7,414 sounds from 411 pigs in different scenarios. They then developed an algorithm to decode whether the pigs were experiencing a positive, negative, or intermediate emotion.

According to the University of Copenhagen the researchers selected commercial pigs, observed from birth to death. In addition to sounds, heartbeats were monitored.

Writes The Guardian, citing study that "because of the impact of emotions on vocalization, vocal expression analysis of emotions is increasingly being considered as an important non-invasive tool for assessing affective aspects of animal welfare."

The same paper mentions that vocalic analysis of different animals has already shown that different emotional states have different acoustic characteristics.

Positive situations include when piglets nurse from their mothers or when they are reunited with family members. Negative situations include separation, fighting, castration, and slaughter.

"There are clear differences in pig vocalizations when we look at positive and negative situations," said Elodie Briefer, a professor in the biology department at the University of Copenhagen who co-lead the study.

"In positive situations, vocalic emissions are much shorter, with small fluctuations in amplitude. The grunts, specifically, start out loud and gradually decrease in frequency" he explained.

"By training an algorithm to recognize these sounds, we can classify 92% of the vocalizations to the correct emotion," he clarified.

According to researchers, most modern animal welfare efforts focus on physical health.