The NHANES 2015-2016 Audiometry Examination Component includes one main audiometry data file (AUX_I) and three middle ear testing data files. The acoustic reflex data file (AUXAR_I) is one of quantitative measurements collected in the middle ear testing to evaluate the functional health of the middle ear system. The acoustic reflex is a protective, automatic reflex contraction of the eardrum in response to a sudden, high-intensity sound stimulus. Acoustic reflex testing results are useful in clarifying questionable tympanograms, verifying degree of hearing loss, and distinguishing between sensorineural hearing losses caused by damage to the cochlea versus the auditory nerve. The propose of the present data file is to provide the underlying raw data curves for this set of acoustic reflexes, which will allow analysts to display actual acoustic reflex curves, make qualitative judgments regarding test adequacy and interpretation, and to perform quantitative analyses.
All adults aged 20–69 years were eligible. Participants using hearing aids but unable to remove them for testing and participants with sufficient ear pain at the time of the exam were excluded.
Beginning in 2015-2016, NHANES used an Interacoustics Titan (middle ear analyzer) to conduct three middle ear tests: tympanometry, wideband reflectance, and acoustic reflex threshold screening. Trained examiners performed the middle ear testing on survey participants in a sound-isolating room in the NHANES mobile examination center (MEC). Acoustic reflex is tested by sending a brief tone into the middle ear loud enough to elicit the reflex and looking for resultant changes in eardrum mobility. Six stimuli (85 dB, 95 dB, and 105 dB at 1000 Hz and at 2000 Hz) were tested for each ear. The acoustic reflex testing produced an electronic output. The single best curve at each stimulus for each ear obtained during the testing was captured and uploaded for data processing. Please see the NHANES Audiometry Procedures Manual for further information on the middle ear testing.
The physical volume calibration of the Titan was checked daily throughout testing and at the start and end of each survey location. In addition, the MEC health technicians ran a sample test on one ear to ensure that the unit is producing clear, normal graphs. The Titan also received an exhaustive National Institute of Standards and Technology traceable calibration check annually.
The MEC health technicians who performed the acoustic reflex testing were professionally trained by a certified audiologist from the National Institute for Occupational Safety & Health (NIOSH). The NIOSH audiologist monitored the performance of each health technician on a regular basis and visited the MEC at least three times per year. Additionally, NCHS Project Officers visited each MEC approximately twice a year to observe the audiometry examinations and verify that standard testing procedures were being followed. NIOSH consultants provided the MEC health technicians with annual retraining and protocol updates.
The acoustic reflex testing collected two array data (time array RFXT001-RFXT170, and compliance array RFXC001-RFXC170) at six stimulus levels (RFXLEVEL 85, 95, 105 dB at 1 kHz; 85, 95, 105 dB at 2 kHz) for each ear (RFXSEAR 1=right ear 2=left ear). All data were automatically captured and uploaded into the NHANES computerized database system. On a continuous basis, a consulting audiologist performed a clinical review of all data for each subject as it was received, checking for quality and consistency. The AUXAR_I data file represents the raw data as it was collected.
The acoustic reflex testing results in a serial of 170 x-y time-compliance variables. There are additional three variables to indicate tested ear, stimulus level (the combination of frequency and intensity) and detected reflex respectively. These data can be used to create acoustic reflex graphs at each stimulus for each ear. Each participant could have up-to12 acoustic reflex graphs: six for the right ear and six for the left ear.
The NHANES 2015-2016 AUXAR_I data format and variables are different from the previous survey cycles. Most participants have 12 records. Some participants have less than 12 records. Eligible participants who did not have any acoustic reflex data on both ears are excluded from this data file. The final AUXAR_I data file contains 51,076 observations and 344 variables.
Note that demographic characteristics (for example, age and gender) are not found on the acoustic reflex raw data file but are provided separately in the NHANES 2015-2016 data file (DEMO_I). To make representative estimates for the U.S. population, the analyst must use the appropriate set of sample weights as described in the AUX_I Documentation.