In Czech author Milan Kundera's 1984 novel The Unbearable Lightness of Being, Sabina, a main character, says, "People are going deaf because music is played louder and louder, but because they're going deaf, it has to be played louder still.” That was written before the iPod and boy, was it prophetic.
We've always said we exist to stem the tide of hearing loss in the world and Asius Technologies is proud to have been part of a paper recently published in Acta Acustica, the official journal of the European Acoustics Association. The EAA is an affiliate member of the International Commission for Acoustics along with the Acoustical Society of America.
This scholarly paper by Texas Tech University Ph.D. candidate R.P. Oates, his professor Dr. David Klein, and Asius Technologies Founder and President Stephen Ambrose, "Kinetic Molecular Theory of Sound Exposure in Personal Listening Devices," explains how acoustic waves enclosed in the ear canal force the tympanic membrane to move 100–1000 times greater than acoustic waves of equal amplitude in open air. Since classical acoustics knowledge has not fully explained this biophysical phenomenon a kinetic molecular theory was used, in conjunction with Special Relativity, to quantify sound pressure exposures in personal listening devices more accurately. With this model, a non-linear dependence of sound intensity on speaker excursion is predicted, demonstrating that earbuds sealed in the ear canal can exceed the US National Institute for Occupational Safety and Health’s (NIOSH) ceiling limit of 140 dB.
This work also re-confirms Stephen Ambrose's prior discovery of the existence of the harmful in-ear pneumatic pressures, which were first revealed in his 2011 AES (Audio Engineering Society) publications using both electronic and fluid dynamics models.
You can download the 4-page paper here, but the bottom line from it is that sound intensity increases non-linearly with speaker excursion size, independent of speaker diameter. Based on the increase in molecular kinetic energy from a speaker excursion, this model predicts that even small excursions and speaker diameters are capable of producing excessive sound intensity levels when enclosed in the ear canal. This model predicts that earbuds sealed in the ear canal have an expanded dB range and can exceed the NIOSH ceiling limit of 140 dB.
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