The first artificial hearing aid. Re-evaluating the role of Paolo Aproino

Abstract

Deafness, with its personal and social burden, has certainly accompanied mankind since the beginning of its existence, meaning that various natural aids to hearing, the cupped human hand the first among them, have assuredly been in use since antiquity. Ear trumpets were essentially the first totally artificial type of hearing aid. The actual history of ear trumpets seems to have begun in the seventeenth century, when written evidence on the matter first appears. The French Jesuit Jean Leurechon, in his Recreation Mathematique of 1624, first mentions funnel-like objects as sound amplifiers, while Sir Francis Bacon, in his Sylva Sylvarum, published in 1627, clearly states that similar objects were already in use as aids to hearing. Giovanni Battista della Porta, in his oft-cited Magiae Naturalis of 1589, offers only a vague and inconclusive description of an aid that would once again imitate natural shell forms and can only be considered as one of the first published references to sound amplification. This work focuses on the contribution of Galileo’s disciple Paolo Aproino who, around 1612–13, presented to Galileo, and through this latter to the court of the Grand duke of Tuscany, an auditory instrument that amplified sound, together with his pioneering experimental studies in the field. Using the experimental method taught by Galileo, Aproino was able to test various forms and materials, deciding upon the final design of the instrument that he then supplied to Galileo in order to construct a metal prototype. This trumpet-like linear ear horn seemed to obtain good results in sound amplification, even though it entailed a certain amount of sound distortion that somewhat reduced the intelligibility of speech. Although Aproino never produced any publications on the matter, his findings became known and impressed the scientific and literary milieu of his time and could therefore have been the initial spur for the future development of sound amplification in the following years.