From the Guidelines
Artifacts and noise in tympanometry tracings are most commonly caused by patient movement, equipment issues, and physiological factors, and can be minimized by ensuring proper patient positioning, maintaining clean equipment, and providing thorough operator training. The causes of artifact or noise in tympanometry tracing can be broken down into several categories, including:
- Patient-related factors, such as movement, talking, swallowing, or breathing during the test, which can create irregular tracings 1
- Equipment issues, including improper probe placement, probe tip blockage from cerumen or debris, air leaks in the system, and equipment calibration problems 1
- Physiological factors, such as patent tympanostomy tubes, tympanic membrane perforations, or the presence of middle ear effusion, which can distort readings 1
- Environmental factors, such as noise in the testing area, which can interfere with measurements
- Anatomical variations, such as narrow ear canals or excessive cerumen, which can prevent proper probe sealing 1
- Operator technique, including incorrect pressure application rates or improper probe angles, which can lead to inaccurate results 1
To minimize these artifacts, it is essential to:
- Ensure proper patient positioning and instructions
- Maintain clean equipment with regular calibration
- Conduct testing in a quiet environment
- Provide thorough operator training
- Recognize potential sources of error, such as cerumen impaction, which is more common in older adults and can be addressed by completely removing obstructive cerumen to allow adequate conduction of sound through the external auditory canal 1
By understanding the causes of artifacts and noise in tympanometry tracings and taking steps to minimize them, clinicians can obtain reliable tympanometric data that accurately reflects middle ear function.
From the Research
Causes of Artifact or Noise in Tympanometry Tracing
- Artifact or noise in tympanometry tracing can be caused by various factors, including intermittent low-frequency noise 2
- The presence of excessive or impacted cerumen can also affect tympanometry outcomes, representing an estimated 10% of the population 3
- Tympanometry is not reliable in infants younger than seven months because of the highly compliant ear canals of infants, which can lead to inaccurate tracings 4
- Measurement noise can obscure information related to pathologies and increase intermeasurement variability, highlighting the need for artifact mitigation techniques 2
- Central, non-auditory processes, such as visual distraction, can also affect simple audiometric measures, including tympanometry 5
Types of Noise and Artifacts
- Intermittent low-frequency noise is a common type of noise that can plague WBT measurements and contribute to artifacts in computed absorbances 2
- Smoothing algorithms can change the true absorbance and destroy important narrow-band characteristics, such as peaks and notches at different frequencies 2
- Artifact mitigation procedures, such as high-pass filters and Tukey windows, can be used to resolve artifacts from low-frequency noise while preserving characteristics in absorbance 2