Fear dictates the way we perceive sounds
It is known that hearing a Mozart sonata influences our emotions and inner state, but now researchers have shown that this could also work the other way. In other words our inner emotions can dictate the way we perceive a melody. If we associate emotions with certain sounds, these sounds can arouse those emotions which were first associated with. Post-traumatic stress disorder (PTSD), as it is called this phenomenon is common in some war veterans who still have strong memories of the battlefield when hearing certain sounds.
However, researchers cannot clearly explain what are the mechanisms underlying this association. Therefore a team of researchers from the Perelman School of Medicine at the University of Pennsylvania have deepened this field and found that fear can increase or decrease the ability to discriminate sounds depending on situation. Senior study author Maria N. Geffen, PhD, assistant professor of Otorhinolaryngology: Head and Neck Surgery and Neuroscience at Penn, said that emotions are closely linked to perception and emotional response helps us face reality. For example, a fear response helps us escape from a dangerous situation and act quickly. But there are situations where things go wrong because of fear. It happens in anxiety or PTSD.
Researchers conducted several experiments on mice to investigate how auditory acuity may change after an unpleasant event. These experiments are based on a process called emotional learning (which is built on classical conditioning, or Pavlovian) and investigate how animals can learn to distinguish between potential hazards and safe sound (“emotional discrimination learning”). Because this type of conditioning usually leads to poor learning, Geffen and Mark Aizenberg, PhD, the first author of the study, created a series of tasks designed to lead to a better emotional discrimination in mice. What interested the researchers was to discover how emotions can affect sound perception and discrimination.
Geffen said that ‘animals presented with the two sounds that were very similar exhibited specialization of their emotional response, while animals presented with sounds that were very far apart generalize the fear that they developed to the danger tone over a whole range of frequencies”. It seems that the effects of emotional learning on auditory perception are processed by the auditory cortex, a brain region that has several roles including the auditory plasticity. What surprised the researchers was that emotional learning is not mediated by this region (the auditory cortex), but by the amygdala and other sub-cortical auditory areas.