Assesment of multifrequency tympanometry in normal-hearing adults

The tympanometry test has been widely used throughout the world since the day it was introduced due to its inexpensiveness, rapidness, noninvasiveness, and its contributions to the diagnostic processes. Initially, the 226 Hz probe tones had been used for the test; however, in the subsequent years, some limitations of the performed measurements by using this frequency were identified. The clinical use of high-frequency probe tones has been suggested particularly in pathological conditions such as otosclerosis, or in the evaluation of the middle ears of the newborns. However, these tests are more complex and determination of the normal quantitative and/or qualitative values are required for widening the clinical use of these tests. Our study was performed with the aim of determining the normal values of the high-frequency tympanometry device used in our clinic. The study group consisted of 56 adults with normal hearing and a normal 226 Hz tympanogram. The MAICO MI 44 device was used for high-frequency tympanometry measurements. Firstly, measurements with the standard 226 Hz probe were performed, followed by measurements at 678, 800, and 1000 Hz probe tone frequencies. The ear canal volume (ECV), tympanometric peak pressure (TPP) and compliance (static admittance) measurements were evaluated regarding the descriptive statistical data (mean value, standard deviation, median value, the highest and the lowest values together with their percentages. Additionally, ECV, TPP and compliance (static admittance) values were compared according to the gender of the participants together with their tympanogram types. The mean age of the study group was 25.2±6.4 (age range 20-53) years. 51.8% (n=29) of the participants were male and 48.2% (n=27) were female. The tympanogram types were determined as two atypical and five double peak tympanograms (DPT) at 678 Hz, one atypical tympanogram and 13 BMTs at 800 Hz, one inverse tympanogram, four atypical tympanograms, and 68 DPTs at 1000 Hz. The average ECV values were 1.07±0.35 ml at 226 Hz, 1.01±0.34 ml at 678 Hz, 0.97±0.28 ml at 800 Hz, and 1.01±0.28 ml at 1000 Hz. The mean TPP values were -32.39±13.97 daPa at 226 Hz, -1.58±19.28 daPa at 678 Hz, 6.28±24.34 daPa at 800 Hz, and 31.22±33.20 daPa at 1000 Hz. The average compliance (static admittance) values were 0.69±0.36 ml at 226 Hz, 1.95±1.16 mmho at 678 Hz, 1.74±0.97 mmho at 800 Hz, and 1.39±0.78 mmho 1000 Hz. The ECV values of the males (1.22±0.36 ml at 226 Hz; 1.16±0.36 ml at 678 Hz; 1.10±0.27 ml at 800 Hz and 1.13±0.27 ml at1000 Hz) were higher when compared to females (0.91±0.27 ml; 0.84±0.21 ml; 0.83±0.20 ml and 0.88±0.22 ml, respectively). The vi differences were statistically significant regarding all frequencies (z=4.933; p=0.000, z=5.003; p=0.000, z=5.443; p=0.000, z=4.671; p=0.000). The compliance (static admittance) values were statistically significantly different at only the frequency of 1000 Hz when compared according to gender (z=2.073, p=0.038). The compliance (static admittance) value of females (1.52±0.81 mmho) was higher than that of males (1.25±0.74 mmho). There were no significant differences between females and males regarding the compliance values at other frequencies, together with the TPP values at all tested frequencies (p>0.05). The tympanogram types obtained in the individuals involved in the study showed no difference regarding gender (p>0.05). The tympanogram types were taken into consideration as two groups, consisting of type A and the other types. At the frequency of 1000 Hz, the TPP values (z=5.743; p=0.000) and the compliance values (z=4.608; p=0.000) showed significant differences regarding the types. The TPP value (11.95±20.57 daPa to 41.52±34.17 daPa), and the compliance value (0.94±0.51mmho to 1.62±0.80 mmho) were higher in the group consisting of other types when compared to the group of type A. The ECV value at the frequency of 1000 Hz, and the ECV, TPP, and the compliance values at the frequencies of 678 Hz and 800 Hz did not have any significant differences regarding the tympanogram types (p>0.05). As the normal values can vary regarding the age, the gender, and the genetic characteristics, they can also show differences according to the used devices and the applied test protocols. The data belonging to the high-frequency tympanometry device, obtained in our study, is planned to be utilized in the studies that we will conduct from now on.