The main NHANES 2011-2012 Audiometry Examination data file (AUX_G) is released in a separate file. This file includes quantitative data for tympanometric measurements. The purpose of the present data file AUXTYM_G is to provide the underlying raw data curves for this set of tympanograms, which will allow analysts to display actual tympanograms, 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 who were not able to remove them for testing and participants who had sufficient ear pain at the time of the exam were excluded.
NHANES employed a Micro Audiometrics Earscan™ Acoustic Impedance Tympanometer to conduct tympanometry testing. Please see the NHANES Audiometry/Tympanometry Procedures Manual for further information on Tympanometry testing.
Tympanic membrane compliance testing was performed by a trained examiner in a sound-isolating room in the NHANES mobile examination center (MEC). A screening questionnaire was administered before testing to assess factors that might have affected tympanometry test results. Analysts should refer to the AUX_G data file for information on the MEC screening questionnaire. In addition, questions on hearing status, including noise exposure history and the use of hearing aids, and prior noise exposure can be found in the Household Interview questionnaire data files for Audiometry (AUQ_G). The tympanometer produced an electronic output, and the single best curve for each ear obtained during testing was uploaded for data capture and processing.
The physical volume calibration of the tympanometer was checked at the start and end of each survey location and daily throughout testing. Air pressure was calibrated automatically by the unit each time it was turned on. The tympanometer also received an exhaustive NIST-traceable calibration check annually. For details of equipment maintenance procedures, analysts should consult the NHANES Audiometry/Tympanometry Procedures Manual.
The automated tympanometer utilizes an electromagnetic impedance unit incorporating a pressure transducer to indicate changes in compliance of the tympanic membrane while simultaneously varying the air pressure in the sealed canal of the same ear. This is accomplished by measuring the sound pressure level of a probe tone introduced into the ear canal (226 Hz at 85 dB SPL), while the air pressure in the ear canal is changing from +200 to -312 dekaPascal (daPa). The equivalent volume is also measured and can range from 0.2 to 7.0 ml. During this procedure, an 84-point tympanogram is recorded, as well as numeric values for middle ear pressure, physical volume, compliance, and gradient (tympanometric width). The variables containing the numeric data for these latter measurements (AUXTMEPR, AUXTMEPL, AUXTPVR, AUXTPVL, AUXTCOMR, AUXTCOML, AUXTWIDR, and AUXTWIDL) are located in the AUX_G data file. Qualitative assessment variables for tympanogram (AUAREQC, and AUALEQC) are also included in the AUX_G data file. Again, please note that the measurements reported in the tympanometry raw data file represent the raw data for single best of two curves obtained during testing.
The tympanometry portion of the data file includes 168 variables, representing equivalent volume (compliance) data for pressure values beginning at -300 daPa, ranging down to +198 daPa. One daPa is equivalent to the pressure of 1.02 mm H2O. Please note that while the tympanogram is obtained during testing by varying pressure from positive to negative, graphically it is traditionally plotted from negative pressure to positive. Accordingly, the last pressure measurement recorded during the test is the first variable listed in the data file. Note also that although the actual test procedure included pressure output from +200 through -312 daPa, data points in the tympanometry curve file include only measurements from +198 through -300 daPa in 6 daPa increments. The responses for a particular ear are contained in a series of 84 equally-spaced sequential measurement variables. The tympanometry variable set for the right ear is AUDTYR01-AUDTYR84; for the left ear it is AUDTYL01-AUDTYL84. Each successive variable represents a 6 daPa increase in applied pressure. For example, for the right ear, AUDTYR01 represents -300 daPa; AUDTYR02 represents -294 daPa; AUDTYR03 represents -288 daPa, etc., through AUDTYR84, which represents +198 daPa. These data can be used to create tympanometric graphs of compliance as a function of pressure for each ear. To do this it is necessary to create a variable to record the associated pressure values. An example of SAS™ programming code to calculate is provided in Appendix A of this document.
The tympanometry examination for 2011-2012 was administered to a full sample of participants in the MEC. Therefore, the NHANES MEC examination weights should be used for data analysis. For more information on the use of sample weights in current NHANES data analysis and for combining weighted data across multiple NHANES survey years please refer to the NHANES Analytic Guidelines and the on-line NHANES Tutorial for further details on the use of sample weights and other analytic issues.
Tympanometry data analysis is a complex procedure and requires a thorough knowledge of the specialty content area for valid results to be obtained. If an analyst does not have professional experience in this area, it is recommended that audiologist consultation be obtained to help formulate and review the results of the analysis.
Appendix A. Sample SAS™ Program for Tympanometric Graphs
The following SAS™ code, or a similar process in another programming language, may be used to obtain tympanometric plots of compliance (y) versus pressure (x) for left and right ear data for individual examinees (identified by SEQN) using the tympanometry raw data file (AUXTYM_G). Note that the use of name-range variable lists in the array statements assumes that the variables are ordered as shown in the public release version of the data file and code book. Variations in ordering for the specified variables will result in errors.
DATA TYMPGRAPH (KEEP=SEQN RIGHT_COMPLIANCE LEFT_COMPLIANCE PRESSURE);
SET AUXTYM_G;
/*Keep statement minimizes dataset size for efficient processing*/
ARRAY LCOMPL (84) AUDTYL01--AUDTYL84;
ARRAY RCOMPL (84) AUDTYR01--AUDTYR84;
J=-300; *Start pressure values at -300 daPa;
DO I=1 TO 84;
LEFT_COMPLIANCE=LCOMPL(I);
RIGHT_COMPLIANCE=RCOMPL(I);
PRESSURE=J; *Associate a pressure value with compliance;
OUTPUT;
J=J + 6; *Increase pressure by 6 daPa for next point;
DROP I;
END;
FORMAT LEFT_COMPLIANCE 5.3 RIGHT_COMPLIANCE 5.3;
LABEL PRESSURE='Pressure in DaPa (1 DaPa= 1.02 mm H2O)';
LABEL LEFT_COMPLIANCE='Compliance in ml';
RUN;
/*Proc GPlot requires sorted input data*/
PROC SORT DATA=TYMPGRAPH; BY SEQN; RUN;
SYMBOL1 COLOR=RED
INTERPOL=JOIN
VALUE=DOT
HEIGHT=0.5;
SYMBOL2 FONT=MARKER VALUE=C
COLOR=BLUE
INTERPOL=JOIN
HEIGHT=0.3;
AXIS1 ORDER=(-300 TO 200 BY 100)
LABEL=(JUSTIFY=CENTER FONT=CENTB
"Pressure in DaPa (1 DaPa= 1.02 mm H2O)")
MAJOR=(HEIGHT=2) MINOR=(HEIGHT=1)
WIDTH=3;
AXIS2 ORDER=(0 TO 2.5 BY 1)
LABEL=(ANGLE=90 JUSTIFY=CENTER FONT=CENTB "COMPLIANCE IN ML" )
MAJOR=(HEIGHT=2) MINOR=(HEIGHT=1)
WIDTH=3;
LEGEND1 LABEL=NONE
POSITION=(TOP CENTER INSIDE)
MODE=SHARE;
PROC GPLOT DATA=TYMPGRAPH;
BY SEQN;
PLOT LEFT_COMPLIANCE*PRESSURE RIGHT_COMPLIANCE*PRESSURE / OVERLAY
LEGEND=LEGEND1
HAXIS=AXIS1 HMINOR=4
VAXIS=AXIS2 VMINOR=1;
TITLE 'NHANES 2011-2012 TYMPANOGRAM';
RUN;
QUIT;