I was fortunate to be at the excellent Ear Science Institute Australia, forum on Friday
“A Life Worth Hearing”
The keynote presenter was Professor James Hall III, who holds academic appointments as Extraordinary Professor in the Department of Communication Pathology at the University of Pretoria in South Africa and Adjunct Professor in the Department of Audiology at Nova Southeastern University in Florida and at Salus University in Pennsylvania. His Keynote was titled “The Future of Audiology”, but was substantially a personal story of the history of audiology in the USA. I thought it was a very good talk, although I think there are one or two Europeans who could have rated a mention. Ignoring that until another blog, I’ve tried to capture the key points from his address here.
Prof Hall shared some of his personal story, and went on to describe the work of SS Stevens (1906–1973), who was based at Harvard University, in the 1940’s.
Stevens was a pioneering psychologist, who put together a “Top Team” to study hearing/psychophysics, known as the Harvard Psycho-Acoustics laboratory. Among other achievements, Stevens is credited with Stevens’ Power Law, which describes the relationship between the magnitude of a physical stimulus and its perceived intensity). Many psychophysicists spent impressionable years at Stevens’ Lab. His distinguished colleagues went on to include George Miller, and Hungarian Georg Von Békésy (1899-1972).
Békésy, who became a Nobel Laureate for his work in Physiology and Medicine, published his first paper on the pattern of vibrations of the inner ear in 1928. During World War II, he worked in telecommunications, which further enhanced his interest in the inner ear. In 1947, he moved to Harvard University, where he stayed until his laboratory burnt down, in 1966.
Békésy developed a method for dissecting the inner ear of human cadavers whilst managing to leave the cochlea partly intact, and he was the first to show that different sound wave frequencies are dispersed along the basilar membrane in a special way, before the different nerve fibres that lead from the inner ear to the brain are excited, and that the position of each hair cell along the basilar membrane corresponds to a specific frequency, a bit like a piano keyboard. He used his observations to develop a mechanical model of the cochlea, which remained the basis of our knowledge of cochlear mechanics for many years. Von Békésy had to devise his own techniques and tools. He needed a means to quantify hearing threshold, and developed an automated threshold procedure, known today as the Bekesy audiometer.
While this foundation work in hearing science was going on, Harvey Fletcher (1884-1981) was working at Bell Labs, where he made significant contributions to our knowledge of speech perception. He showed that speech features are usually spread over a wide frequency range and he developed the articulation index to approximately quantify the quality of a speech channel. He also developed the concepts of equal loudness contours, now commonly known as Fletcher-Munsen curves.
Hall next described the contribution of Hallowell Davis (1896-1992) who was a key figure in the development of the electroencephalogram (EEG). He specialised in studying changes caused to the base pattern by presenting auditory stimuli. This work lead directly to the development of auditory evoked potentials, which, among other things, allowed diagnosis of hearing difficulties in infants. Hallowell Davis is attributed to have coined the word “audiology”. He co-authored a book with Richard Silverman, called Hearing and Deafness, in 1947 and it remained a key audiology study text for about the next 30 years. The electrophysiology work of Hallowell Davis, was continued by Bob Galambos (1914-2010),a neuroscientist who is credited with developing the auditory brainstem response. Galambos was another Harvard man, and performed experiments there, for the military, on the relationship between the shock waves from explosions and hearing loss. He built on the work of Davis, and using electrodes implanted in the brains of animals, he was able to use electronic amplifiers to boost the signals of a single nerve to follow the impulses that travel from the ear to the brain in response to auditory stimuli. This was the foundation of the clinical test used today, the auditory brainstem response, which allowed him to track how neurons respond to the presence of sound at a particular frequency. This research allowed for the development of hearing tests for infants which could be performed by monitoring the brain’s response directly to sounds.
Another of the Harvard Psychoacoustics lab graduates was Ira Hirsh (1923 -2010), who did pioneering research in human hearing, auditory perception, communication, speech, language and communication disorders. His research on sound perception was important in improving hearing aids and teaching methods for deaf children. He laid the foundations for speech audiometry.
During and after the Second World war, there was a need to identify and rehabilitate returning service men who had damaged their hearing as a result of war time service. Raymond Carhart (1912-1975) became a speech pathologist in the US army Medical Administrative Corps.
Carhart, known as the father of diagnostic audiology, is associated for much of his career with NorthWestern University, where he developed rehabilitative audiology at a time when hearing aids were not very good. The Veterans Administration (VA), was established in 1930, and re-organized in 1944. There was a big demand for auditory rehabilitation services and both VA clinics and some universities with audiology clinics provided government-sponsored aural rehabilitation services for the veterans.
If Raymond Carhart is the father of Rehabilitative audiology, then Professor James Jerger, another NorthWestern graduate, is the father of diagnostic audiology. He led the move to establish the American Academy of Audiology at the American Speech and Hearing Association (ASHA) Convention in New Orleans in 1987. Today, the American academy of Audiology, of which I’m an International Fellow, is the largest audiology member based organization in the world. Jerger has also been a visionary in pushing the American audiologists to a professional doctoral program. The establishment of AAA in the USA was clearly an exciting milestone in the history pf audiology. I wish I’d been there.
In Professor James Hall’s address last week, he was keen to echo Jerger’s plea that the different voices in audiology should unite to give the profession a continuing strong reputation. He quoted Leonardo Da Vinci:
“Where there is shouting, there is no true knowledge”
I couldn’t agree more. Thank you Professor Hall (and Leonardo, of course)