Tag Archives: vibrations

Good Vibrations Part Two.

These Tuning fork tests give qualitative rather than quantitative results. It was not until the invention of the telephone in 1876 that quantitative data on hearing loss could be compiled through the use of the audiometer, which was invented by David Edward Hughes just two years later, in 1879.

The audiometer is an instrument that is integral to many of the themes of my thesis on telephony and hearing loss, as an instrument developed from the telephone in order to measure and classify widespread hearing loss, particularly in the military. Despite being developed at the end of the 19th century however, it was not until after the Second World War that it gained widespread acceptance. This is because it became necessary to test many people quickly and have a numerical result that could be compared before and after service in order to award or refuse compensation for noise induced hearing loss. The audiometer had not been taken up previously largely due to practitioners reluctance to use the more complicated instrument when tests like the watch tick test, spoken voice (Smellen) test or tuning fork test were far simpler. Debates over the utility of these tests intensified in Britain after the First World War, when doctors were faced with treating soldiers suffering from both noise induced hearing loss and temporary hearing loss caused by shell shock.

In 1928, the British Medical Journal devoted an article to a report on the issue of tests and classification of hearing, in which various medical authorities held forth on the subject. Mr Somerville Hasting started the debate with the statement that he was convinced that, from the point of view of scientific advance, arbitrary units of hearing must be given up.’ He was met with the response that, ‘ For distance-tests a watch was useful, but the instrument known as the electrical audiometer, while valuable for research, was, he considered, impossible for ordinary clinical use, owing to its complication and lack of portability. Tuning-forks yielded accurate results.’

The endurance of tuning forks may also lie, as M.Ng & R.K. Jackler imply, in their ‘appeal to other for their elegant simplicity’.In my mind, there is certainly something intrinsically satisfying in the process of striking these cool steel devices against a hard surface to create a resounding and resonating ting.

Tuning fork frequency demonstration.

The tuning forks featured in these videos and photographs are just a small part of the wonderful linguistic and phonetics collection held within the museum of History, Science and Medicine at Leeds (HSTM).  In the background to the video and the featured image in this post are a beautiful collection of books describing the dialects of India, which also contain annotations by Professor Daniel Jones, who was one of the people who inspired George Bernard Shaw to write the character of Henry Higgins (Alexander Melville Bell, Alexander Graham Bell’s Grandfather has also been cited as inspiring this role).  Professor Daniel Jones was involved with the Leeds phonetic department when it began in 1947.

The tuning forks were also part of the equipment held by the department at its inception and they range over an octave at frequencies 256-512 kHz. This indicates that these were musical tuning forks, possibly used to tune instruments rather than test hearing. Modern concert pitch (or international standard pitch) was only established in America in 1939 so it is unsurprising that this earlier British set does not correspond to these frequencies. The forks were manufactured in Sheffield, an industrial town close to Leeds, famous for manufacturing more conventional crockery as part of its steel industry.

These tuning forks are now on display as part of the ‘Hidden Histories’ exhibition, which is situated, most appropriately for this example, in the foyer between the department of philosophy, religion and history of science and the department of linguistics and phonetics. Check out the exhibition to see why they are my favourite thing in the museum and see more objects that other students have a particular affinity with.

Good Vibrations Part One


Notes

[1] Newby. H.A & Popelka G.R, Audiology ( Prentice Hall Inc, 1985)p.104-105

[1] J. Blauert, The Psychophysics of Human Sound Localisation, (MIT Press, 1997)

[1] M.Kay, ‘Making uses for telephone instruments: the health, safety and security innovations of medical, mining and military users’ in Inventing telephone usage: debating ownership, entitlement and purpose in early British telephony.

[2] BMJ Nov 17th, 1928

[4] M.Ng & R.K. Jackler, ‘Early History of Tuning Fork Tests’ p.105

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Good Vibrations Part One.

‘Theoretically there was no normal hearing power, but practically there was, and was found to vary from 32 to 35,000 vibrations per second. This could be tested by properly constructed tuning-forks, as oculists tested by lenses the normal visual range.’  – Professor Marcel Natier in the British Medical Journal, 1904.

University of Leeds Phonetics Department Tuning Forks.

University of Leeds Phonetics Department Tuning Forks.

The tuning fork is a fascinating object because its history reveals how theories of sound, music, hearing loss and communication have intersected in the past to inform the way we measure hearing loss today. The possibility of hearing through bone conduction by vibrations travelling through the bones around our ears had been discovered in 1550 but it was not until 1711 that the tuning fork was invented to utilise the potential of this discovery. John Shore, trumpet and lute player in the Royal Court, was attributed with its invention as a musical instrument, which allegedly came about because he had split his lip and was unable to play his trumpet.Tuning forks became widely used in music for tuning purposes and for establishing pitch rather than as instruments in themselves because they produce pure tones.

In 1827, Sir Charles Wheatstone was the first to use the tuning fork to assess hearing and realised that when both ears were blocked, sound lateralised (travelled) to the side nearest to the origin of the sound. Wheatstone is famed for his work with telegraphy and for inventions like the Wheatstone bridge and the Cooke -Wheatstone telegraph yet there is less known about his role in establishing standards for hearing testing. He grew up in a musical family however and was for some time apprentice to a musical instrument maker, which may indicate his interest in tuning forks. His interest could be explained further by the fact that studies of acoustics were proliferating in the late nineteenth century, especially as comparative pieces to the more widely studied subject, optics, as the epigraph to this piece also suggests. The late nineteenth century is notable furthermore because it was a time in which measurement and standardisation became of defining importance to science and tuning forks were used in this way to define standards of pitch and frequency, which were then related to speech and to hearing.

Wheatstone’s essential role in developing hearing tests as well as pioneering telegraphy further points to the close link between hearing loss and communication. It is well known that Alexander Graham Bell attributed his invention of the telephone to his work with the deaf and more recently historians like Mara Mills have described how measuring and classifying normal hearing and hearing loss was essential to the development of the telephone network.

The Weber Test.

In 1834, Ernst Heinrich Weber realised that Charles Wheatstone’s discovery could be used to differentiate between conductive and sensori-neural hearing loss when there is either a unilateral hearing loss or a difference in hearing between one ear and the other. This works by placing the handle of a vibrating tuning fork in the centre of the skull. If the sound is heard in the better ear this indicates sensori-neural hearing loss but if it is heard in the worst eat, this indicates conductive hearing loss. This works because when someone has sensori-neural hearing loss, the sound is localised through bone conduction in the better ear but for someone with bone conductive hearing loss the sound travels (is localised) to the worst ear. Although various kinds of tuning fork hearing tests proliferated in the late 19th and early 20th century, the Weber Test and the Rinne test were the most common and remain in use today.

Weber test demonstration.

The Rinne Test.

Heinrich Adolf Rinne developed this hearing test in 1855 in order to differentiate between conductive hearing loss and sensori-neural hearing loss. This works by measuring how long the tuning fork tone can be heard thorough air conduction (by holding the fork close to the ear) compared to bone conduction (by placing the handle of the fork on the mastoid).  If the fork is heard longer through bone conduction then this indicates conductive loss but if it is heard longer through air conduction then this indicates sensori-neural loss.By 1985, it was established that these tests were to be conducted by using forks vibrating at C on the scientific scale through frequencies 128hz- 8192 hz. This roughly reflected the frequency at which most speech is usually heard, on a spectrum from 16hz to 20khz.

Rinne Test Demonstration.

Thank you to Anne Hanley and Sean McNally – the stars of the featured videos!

Good Vibrations Part Two



REFERENCES AND FURTHER READING

Blauert J, The Psychophysics of Human Sound Localisation, (MIT Press, 1997)

Mills M, ‘Deafening: Noise and the Engineering of Communication in the Telephone System’ in Grey Room, Spring Issue, No. 43, (Inc. and the Massachusetts Institute of Technology 2011) pp.118-14

Newby. H.A & Popelka G.R, Audiology ( Prentice Hall Inc, 1985)p.104-105

Ng, M & Jackler R K, ‘Early History of Tuning Fork Tests’ in History of Otology (The American Journal of Otology) Vol. 19, No.1, Jan 1993 (pp 100-105)

Rees T, ‘Historical notes: a brief chronicle of the tuning fork’, in  Explore Whipple Collections, Whipple Museum of the History of Science, University of Cambridge, 2009 <http://www.hps.cam.ac.uk/whipple/explore/acoustics/historicalnotes/,&gt; (accessed 20 November 2014]