A Pure Tone Audiometry (PTA) hearing test is a common method used by audiologists to evaluate an individual’s hearing sensitivity. This behavioral test measures the softest sounds a person can hear, providing a basis for diagnosing and managing hearing loss. It assesses hearing function in adults and cooperative children.
Understanding Pure Tone Audiometry
Pure tone audiometry focuses on “pure tones,” sounds with a single frequency or pitch. The test’s main goal is to identify the quietest sound an individual can hear at different pitches, known as their hearing thresholds. These thresholds indicate the softest sound that is audible at least 50% of the time.
The testing covers frequencies from 250 Hertz (Hz) to 8000 Hz, a spectrum important for understanding speech. Though the human ear detects a wider range, these frequencies provide sufficient clinical information. Measuring these thresholds helps identify the type, degree, and configuration of any hearing loss.
How the Test is Performed
A PTA hearing test is conducted in a sound-proof booth to minimize external noise and ensure accurate results. The main equipment is an audiometer, which generates pure tone sounds at specific frequencies and controls their intensity. Sounds are delivered through headphones or insert earphones for air conduction testing, and sometimes through a bone conductor placed behind the ear for bone conduction testing.
During the test, individuals are instructed to respond each time they hear a tone, no matter how faint, by pressing a button or raising a hand. The audiologist presents tones at varying frequencies and intensities, starting with softer volumes and gradually increasing them until a response is obtained. This process, often following the modified Hughson-Westlake method, determines the decibel level at which an individual consistently hears each frequency. The pure-tone testing portion of a comprehensive hearing evaluation takes about 15 minutes.
Interpreting Your Hearing Test Results
The results of a PTA test are presented on a graph called an audiogram. The audiogram has two axes: the horizontal X-axis shows sound frequency (pitch) in Hertz (Hz), from low (e.g., 125 Hz) to high (e.g., 8000 Hz). The vertical Y-axis shows sound intensity (loudness) in decibels hearing level (dB HL), with quieter sounds at the top (e.g., -10 dB HL) and louder sounds at the bottom (e.g., 110 dB HL).
Hearing thresholds, the quietest sounds heard at each frequency, are plotted on this graph. Normal hearing falls between -10 dB HL and 25 dB HL. Different patterns on the audiogram indicate various degrees of hearing loss, such as mild (26-40 dB HL), moderate (41-55 dB HL), severe (71-90 dB HL), or profound (above 90 dB HL). The difference between air conduction and bone conduction results, known as the air-bone gap, helps audiologists determine the type of hearing loss, such as conductive (outer or middle ear issues), sensorineural (inner ear or auditory nerve damage), or mixed (a combination of both).
Next Steps After Your Hearing Test
After the test, the audiologist will discuss the results, explaining what the audiogram reveals about your hearing. If hearing loss is identified, they will clarify its type and degree. This conversation is an opportunity to ask questions and understand your hearing profile.
Based on the findings, the audiologist will recommend next steps. These may include continued hearing monitoring, additional diagnostic tests like speech audiometry or tympanometry, or specific interventions. For those with hearing loss, recommendations might involve hearing aids, assistive listening devices, or a referral for medical treatment if a treatable condition is identified, such as earwax blockage or certain middle ear issues.