One ”Compressed sound” is a digital sound that has been “tassé” electronically to raise the lowest sound levels, so that it is more audible.
The sound of franceinfo is slightly compressed. Just like the vast majority of music and sounds that we listen to on the internet, on DVD or in videoconference when we telecommute.
This format has become widespread because compressed sound has the advantage of being placed above ambient noise, which allows for greater listening comfort. But obviously the compression of the sound does not have only advantages. The downside is that the ears receive stronger sound energy and with less nuance than with classic sound, explains Christian Hugonnet, acoustical engineer and president of the Semaine du son which will be held next week.
Researchers from Inserm and the Faculty of Medicine of Clermont-Ferrand therefore wanted to know if these compressed sounds represented a danger for the ears. For this, they therefore made 90 guinea pigs listen to music for several hours, because they have a hearing system similar to ours. Some guinea pigs were entitled to compressed music and others to music in the original format. They listened to pop, classical or even electro, there was something for everyone.
These guinea pigs were then entitled to an ENT examination. Good news: none had lost hearing. But guinea pigs who listened to compressed music suffered hearing fatigue for more than 48 hours. The protective muscles inside their ears were weakened.
The compressed sound no longer contains any silence, explains Prof. Paul Avan, who led the research. There are not even the few milliseconds of white, which can be found in uncompressed or moderately compressed sound, so the auditory system has no respite, it is asphyxiated. Some doctors make a connection between the increase in certain hearing disorders in young people and listening to these sounds, but if this auditory fatigue is demonstrated in animals, it has yet to be proven in humans.
What are the prevention solutions, since compressed sounds are already everywhere? A scientific committee is about to be created to see if it is possible, in the future, to label less compressed sounds and guaranteed “without danger”: they would contain the few milliseconds of silence necessary to leave the ears ” to breathe”.