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Figure 1. Philocophus or The deafe and dumbe mans friend (Bulwer, 1648). This is the frontispiece of this work, which is the first known representation of bone conduction. Middle left: man next to the cello “listening” to the cello with his teeth to illustrate bone conduction. Middle right: effects of speech articulation by blowing smoke. Bottom: four faces (left to right): The first head shows a man with his mouth not in the normal position but located in the middle of the nose (smell), meaning that he can taste through his nose. The second man lacks a nose, and his mouth is shifted to the area of his nasal root, meaning that he can smell through his mouth (taste). The third man is blind; however, in each auricle an eye is engraved, thus he is able to see with his ears. The man on the right has no ears, but he hears with the right eye that is shown by an auricle replacing the eye (Pirsig and Stephens, 1994, p. 115). From the author’s collection
Figure 2. Wolke’s acoumeter was a wooden board (n, o, c, m,) placed upright. Attached to it was a drumstick (c, ch), which was dropped onto the board from various heights as measured by the protractor (Q) that determined the amplitude (Wolke, 1802).
were exposed to electrical auditory stimulation. Wolke’s work was based on the observations of Volta and many others (reviewed by Marchese-Ragona et al., 2019). Wol- ke’s (1802) instrument, an acoumeter, was a wooden board placed upright, attached to which was a drumstick that could be dropped onto the board from various heights as determined by a protractor (Figure 2) that measured the amplitude of the sound. Itard (1821) described a similar instrument made of metal for ascertaining whether or not there was improvement in the hearing of deaf children after hearing exercises using voices.
School Screening
It was long recognized that school children with a hear- ing impairment would be at a disadvantage in learning and would often be considered mentally retarded. Blake (1876), a physician, recognized the need to determine which children had a hearing loss and created a screen- ing program for school age children. Each child would have his/her hearing assessed by recording his/her ability to detect speech at a fixed distance from the teacher. The teacher spoke a proscribed series of test words based on the work of German investigator Wolf (1871) that were selected for the way in which they are affected by a hearing
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