The NHANES 2015-2016 audiometry exam component includes one main audiometry data file (AUX_I) and three middle ear testing data files. This wideband reflectance data file (AUXWBR_I) is one of three middle ear testing to evaluate the functional health of the middle ear system. It is a new quantitative measurement collected beginning in 2015-2016. The wideband reflectance measures the transmission of sound through the eardrum across a range of frequencies while ear canal pressure remains constant. The propose of the present data file is to provide the underlying raw data curves for this set of wideband reflectance, which will allow analysts to display actual wideband absorbance 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. Wideband reflectance measures the movement of the eardrum in terms of how much sound is transferred through the middle ear system across a range of frequencies at a single pressure (ambient air pressure – usually 0 daPa). Trained examiners performed the middle ear testing on survey participants in a sound-isolating room in the NHANES mobile examination center (MEC). The wideband reflectance testing produced an electronic output. The single best curve 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 wideband reflectance 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 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 wideband reflectance testing collected three array data (frequency array WBXF0001-WBXF107, absorbance array WBXA001-WBXA107, and phase array WBXP001-WBXP107) for each ear (WBXFEAR 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. Absorbance array data point values outside the expected range of 0 to 1 represent some sort of artifact in the wideband absorbance recording or the presence of an additional sound in the ear canal (for example, an otoacoustic emission). The AUXWBR_I data file represents the raw data as it was collected.
Static wideband reflectance testing results in a series of 107 x-y-z coordinates that measures sound absorbance and phase as a function of frequency when the pressure in the ear canal is held constantly (at atmospheric pressure – usually 0 daPa). Results may be plotted two dimensionally with frequency (in Hz) along the x-axis and absorbance (in percent of sound energy) or phase (in degrees) along the y-axis. The absorbance-by-frequency graph summarizes the efficiency of sound transmission through the middle ear system across the audiometry frequency range. The phase-by-frequency graph identified resonant frequencies within the middle ear system (i.e., where phase approaches zero). Most participants have two curves: one for the right ear and one for the left ear. Some participants have only one curve: either right ear or left ear. Eligible participants who did not have a wideband reflectance test on both ears are excluded from this data file.
The Titan measures absorbance and phase at discreet frequency interval during wideband reflectance testing. Therefore, although absorbance and phase measurements will vary for each measurement, the frequency values will always be the same. The frequency measurement is range from 226 to 8000 Hz. Absorbance values range from 0 to 1 and are typically converted to percentage when plotting. Values above or below this range may represent an artifact in the recording or indicate the presence of a physiological sound generated in the ear canal (such as an otoacoustic emission). Phase values range from -180 to +180.
The AUXWBR_I is a new public released data file collected beginning in the NHANES 2015-2016 cycle. Most participants have two records (one for the right ear and one for the left ear). Some participants have only one record (either one of the ears). Eligible participants who did not have wideband reflectance data on both ears are excluded from this data. The final AUXWBR_I data file contains 8,554 observations and 323 variables.
Note that demographic characteristics (for example, age and gender) are not found on the wideband reflectance 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.