Description
The vowel sounder is used to imitate the sounds of five different vowels. Two brass columns support a horizontal bar with five discs, cut with grooves. The bottom of the grooves are indented with ridges and furrows in a very specific manner. A thin metal rod can be placed in contact with the cut discs, connecting them to the circular plastic diaphragm. By turning the handle, the horizontal bar rotates, causing the grooves to move in a spiral course along the rod. The indentations in the grooves create vibrations in the rod, which cause the diaphragm to vibrate at the same frequency as the rod. This amplifies the series of vibrations as it causes movement of air particles, and thus a vowel sound can be heard. The metal rod and diaphragm are able to slide between the five discs depending on which vowel sound is required. This machine is inscribed with ‘oo’, ‘o’, ‘ah’, ‘a’, ‘e’ sounds.

The vowel sounder was designed by Johannes Matthias Augustus Stroh (1828-1914), who aimed to reproduce the structure of human speech as theorized by Hermann von Helmholtz (1821-1894). Helmholtz argued that vowels are compound musical tones, formed through the combination of non-harmonic resonances, which are referred to as formants. The nature of the vowel depends on the relative intensities of these different formants, which in turn depend of the positioning of the vocal tract. When the jaw and tongue are moved into certain positions, the vocal tract resonances are adjusted to produce the pattern of formants characteristic of that vowel. Therefore vowel sounds are composed of a fixed set of frequencies, which are unaffected by the pitch of the voice. The grooves in the discs of this machine are cut in such a way that cause the vibrations of the diaphragm to reflect the combination of frequencies found in vowel sounds, resulting in the production of a similar sound.

Stroh built four talking machines in early 1878, the third of which was the vowel sounder. The second machine etched the sound waves of the formants of vowel sounds onto the brass discs used in the vowel sounder, and the fourth played discs with complete words such as ‘mama’ and ‘papa’. In February 1879 the vowel sounder was exhibited to the Royal Society along with a paper entitled Studies in Acoustics: On the Synthetic Examination of Vowel Sounds. The vowel sounder was created a year after Thomas Alva Edison’s (1847 -1931) first phonograph, a device for recording and replaying sound that also used the idea of spiral discs. However, Stroh’s developments focused more on the scientific understanding of the composition of sound rather than Edison’s more popular appeal. This vowel sounder was built by W. Groves in the late 19th Century.

14/04/2008
Created by: Jonah Lipton on 14/04/2008