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  • Updated 04.29.2024
  • Released 12.06.2014
  • Expires For CME 04.29.2027

Pure-tone audiometry (audiogram)

Introduction

Key points

• Audiometry measures the range and sensitivity of a person's sense of hearing.

• Pure-tone audiometry utilizes a series of pure tones presented at selected frequencies within the hearing range essential for understanding speech to develop a profile of auditory acuity.

• An audiogram provides a graphical summary or profile of auditory acuity as a function of sound frequency, which can be used to characterize the degree, type, and configuration of hearing loss.

• With conductive hearing loss, hearing is impaired for air-conducted sounds but not for bone-conducted sounds, producing an air-bone gap on the audiogram, whereas with sensorineural hearing loss, hearing is impaired for both air- and bone-conducted sounds.

• There are different audiogram patterns for different causes of sensorineural hearing loss: presbycusis is typically associated with a downward-sloping high-frequency loss pattern; noise-induced hearing loss is typically associated with a notched pattern (generally at 4 kHz); and Meniere disease is associated with a low-frequency trough pattern.

Historical note and terminology

Audiometry measures the range and sensitivity of a person's sense of hearing. In general clinical use, this typically incorporates a battery of tests of a person’s hearing ability and related assessments of the function and integrity of the ear and its neural projections. Subjective audiometry includes pure-tone audiometry, speech audiometry, and Bekesy audiometry, whereas objective audiometry includes acoustic impedance audiometry or tympanometry and evoked-response audiometry.

This article addresses the basic interpretation of pure-tone audiometry as measured using a pure-tone audiometer and summarized in a standard graphical format called an audiogram. An audiogram is a convenient tool that characterizes the degree, type, and configuration of hearing loss.

Audiogram
This is the standard audiogram format, with auditory acuity plotted as dB HL (decibels hearing loss) along the y-axis and the frequency of the pure-tone auditory stimuli plotted in Hz (hertz or cycles per second) along the x-axis....

As early as 1885, Arthur Hartmann designed an “auditory chart” that graphically presented acuity to standard tuning forks as a function of frequency (38). Later means of graphically presenting auditory acuity as a function of frequency were developed in the early 20th century (38).

In 1899, American psychologist Carl Emil Seashore (1866–1949) invented an audiometer that was marked initially around 1900 (30; 33; 23; 38). In the 1920s, Western Electric developed a commercially successful electronic audiometer (38). It underwent a series of technological improvements, including the incorporation of bone-conduction testing capability by 1928. An early type of automated audiometer was invented by Hungarian-American biophysicist and Nobel laureate Georg von Békésy (1899–1972) and released in 1946.

Carl Seashore
Carl Seashore developed one of the first commercial audiometers around 1899. (Contributed by Dr. Douglas Lanska.)

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