Harsh Sounds Like Screams Hijack Brain Areas Involved In Pain And Aversion, Making Them Impossible To Ignore

By Emma Young You see a pedestrian about to step out in front of an oncoming car.  Is it better to calmly call out a warning, or to scream? Of course, it’s better to scream — but not just because a scream is loud. Car alarms, police sirens and smoke alarms are all loud, too. But, like screams, they also fall into a particular frequency range, usually between 40 and 80 Hz, and they are acoustically “rough” — they’re perceived as being a repetitive stream of discrete sounds, rather than one continuous one. Quite why such sounds should be so attention-grabbing, and even unbearable, hasn’t been clear. Now a team led by Luc Arnal at the University of Geneva has found that this type of sound triggers activity in brain areas related not just to hearing but also to aversion and to pain. This makes them impossible to ignore. For the new study, published in Nature Communications, 16 participants listened to streams of repetitive clicks at different frequencies, between 50 to 250 Hz. At frequencies below about 130 Hz, participants could hear discrete clicks. Above this frequency, the clicks were usually perceived as being one continuous sound. While very loud sounds were considered unpleasant, the participants found rough sounds in the frequency range of 40-80 Hz particularly awful. This is “in the range of frequencies used by alarms and human screams, including those of a baby,” notes Arnal. To explore why these sounds should trigger such a response, the te...
Source: BPS RESEARCH DIGEST - Category: Psychiatry & Psychology Authors: Tags: Brain Perception Source Type: blogs