Clinical audiology as a distinct profession emerged from the aural rehabilitation programmes the US military set up during and after World War II. Thousands of veterans returned with noise-induced hearing loss from gunfire, explosions, and aircraft engines. Existing otolaryngology services could diagnose, but the scale of the rehabilitation problem — fitting hearing aids, training speech-reading, counselling — exceeded what medicine alone could handle.
Raymond Carhart, a speech-language pathologist with a PhD from Northwestern University, was tapped to direct the aural-rehabilitation programme at Deshon General Hospital in Pennsylvania (1944–1946). He developed the audiometric techniques that the US Veterans Administration then propagated nationally — including the speech-reception threshold (SRT), the speech detection threshold, and quantitative methods for hearing-aid candidacy. After the war Carhart returned to Northwestern and built the country’s first university programme in audiology (the term “audiology” was itself coined around this time, from the Latin audire “to hear” plus the Greek -logia “study of”). He is widely regarded as the father of the field.
The American Speech-Language-Hearing Association (ASHA) issued its first audiologist certification in 1959. The clinical doctorate (AuD) was introduced in the 1990s as the entry-level credential. Today audiology in the US is a doctorate-required clinical profession with about 15,000 active practitioners; analogous credentials exist worldwide.
Most of the standardised tests this book covers — pure-tone audiometry calibrated in dB HL, the Carhart-notch interpretation, the SRT, the basic tympanogram types — descend more or less directly from the Northwestern programme and its WWII-era origins. The instruments have grown immensely more sophisticated; the conceptual structure that organises their interpretation is largely Carhart’s.