Pure tone audiometry is a fundamental hearing test used to identify hearing threshold levels of an individual, allowing for the determination of the degree and type of hearing loss. While the core steps and procedures of this test have remained consistent, advancements in technology and methodology over the years have significantly enhanced its accuracy and reliability. Continue reading this blog to explore the evolution of pure tone audiometry.
The Development of Audiometers
The first audiometers were developed in the early 20th century. These devices were designed to measure hearing sensitivity using pure tones at various frequencies. The early audiometers were manual and required the audiologist to adjust the frequency and intensity of the tones by hand. Although the design of these audiometers was simple, the mechanics and results were groundbreaking for the time. This was the equipment that gave the first valuable insight into hearing loss and helped establish the basic principles of audiometric testing.
Modern Techniques and Standardization
In the 1940s, more sophisticated audiometers with electronic controls were introduced. These devices allowed for more efficient testing by electronically adjusting the frequency and intensity of the tones. This reduced the potential for human error and improved the reliability of the results, ensuring greater accuracy in the presentation level and confidence that the sound being presented was exactly what was intended.
The mid-20th century is also when the Hughson Westlake procedure was introduced. Hughson Westlake, otherwise known as the ascending method, is a consistent pure tone test procedure. The principle behind this method is that short bursts of tone are more easily heard against a silent background compared to a continuous tone with brief intervals during level changes. The procedure starts with short tone bursts at a clearly audible level, then decreases the level by 10 dB until the patient no longer responds. From this point, the tone is increased in 5 dB increments. To establish a hearing threshold, two out of three or three out of five ascending responses at the same intensity are required.
As the field of audiology grew, there was a need for standardized procedures to ensure consistency and accuracy in testing. The International Organization for Standardization (ISO) and the American National Standards Institute (ANSI) published standards for pure tone audiometry, which provided guidelines for calibration, test environment, and procedures.
These standards have been periodically updated to incorporate new research and technological advancements, however, the principle behind this method has remained unchanged since 1944—highlighting the accuracy of original pure tone audiometry test.
Innovations in Audiometry
Advancements in research have further refined pure tone audiometry through technical and procedural innovations. In addition to the advancement of audiometers, additional forms of pure tone testing have been developed to fit specific scenarios and demographics, like automated audiometry.
GSI AMTAS
GSI introduced GSI AMTAS, or Automated Method for Testing Auditory Sensitivity, to assist audiologists in obtaining basic pure tone air and bone thresholds. GSI AMTAS frees up clinicians, enabling them to attend to other patients simultaneously. GSI AMTAS features a table of patented Quality Indicators, which provide overall reliability and key insights into the testing process. Additionally, GSI AMTAS has expanded access to hearing testing for demographics that would otherwise be underserved due to geographical constraints.
Clinical Applications
Pure tone audiometry determines thresholds for each ear and uses frequency-specific pure tones to produce location-specific responses to produce the big picture of hearing status, allowing audiologists to identify the configuration of hearing loss. By using both air and bone conduction audiometry, the type of hearing loss can also be determined via the air-bone gap.
Since its inception in the 19th century, pure tone audiometry has evolved significantly while maintaining its core methodologies. Grason-Stadler, has paid close attention to the pain points within the field and has focused on providing audiometric solutions with the audiologists' needs at the center. Recognizing the gap in access to hearing healthcare, GSI introduced GSI AMTAS. This innovation enables clinicians to extend their reach, providing high-quality care to more patients without compromising on expertise or attention.
As technology continues to progress, the field of audiology can anticipate even greater improvements in the efficiency and effectiveness of pure tone audiometry, ensuring that the core methodologies remain steadfast while embracing new advancements.
Learn more about how GSI has incorporated the fundamentals of pure tone audiometry into GSI AMTAS: https://www.grason-stadler.com/products/audiometers/gsi-amtas