Results of Federichi Tuning fork test in different bone-air gap sizes
Authors: Zabolotny Dmitry I. , Lutsenko Viktor I. , Belyakova Irina A. , Nechiporenko Pavlo V. , Situkho Maksym I. , Kholodenko Tetiana Yu. , Hradiuk Nataliya M. 
Published: November 2021

Background: Tuning fork tests, in particular the Federici test, allow to some extent verifying the correctness of subjective audiometry. During the Federici test patients should compare the volume of the tuning fork placed on the tragus or mastoid process. Federici test is considered positive if the sound seems louder from the tragus than from the mastoid process. Federici test is considered negative if the sound of the tuning fork seems louder from the mastoid process than from the tragus. Literature data indicate that the results of certain tuning fork tests may be different if tuning forks are made of different alloys. Publications describing the characteristics of Federici test at presence different sizes of air-bone gap (ABG) are extremely limited.
Aim: improving the effectiveness of the hearing loss diagnosis by clarifying the Federici test value in case of conduction hearing loss.
Materials and methods: We analyzed 50 audiograms with a sizes of ABG of 10 dB or more at 125 Hz to clarify when the Federici test can be positive or negative. All tuning fork tests were performed with C128 aluminum tuning forks. The Federici test method: after activation the tuning fork it is placed on the mastoid process, then on the tragus. The forms were marked with the results of the following tuning fork tests: Weber, Federici, Bing; and the distance of the patient's perception of whispered and spoken language, the results of audiometric Weber test, pure tone (in the conventional frequency range) and speech audiometry.
Results and discussion: Among the audiograms with ABG, a positive Federici test (group I) was observed in 39 cases (57 %), and a negative test (group II) was observed in 30 cases (43 %). Assessment of hearing loss was performed according to the criteria by Bazarov VH and Rozkladka AI (1989). The results of first group: the first degree of hearing loss was registered in 30 cases (76.9 %), the second degree in 6 cases (15.4 %) and the third degree in 3 cases (7.7 %). The results of the second group were following: the first degree of hearing loss was registered in 24 cases (80 %), the second degree was registered in 2 cases (6.7 %) and the third degree was registered in 3 cases (13.3 %).
The article contains tables with data of sizes of ABG at different frequencies in cases of positive and negative Federici tests, as well as the difference between air and bone conduction in speech audiometry (performing the test of 50 % numerals discrimination threshold by Kharshak). There are samples of audiograms for both positive and negative Federici tests with the same ABG size given.
Conclusions: We studied the characteristics of the Federici test performed with C128 aluminum tuning forks in patients with different sizes of bone-air gap at a frequency of 125 Hz. When ABG is from 10 to 35 at a frequency of 125 Hz, the Federici test can be both positive and negative, because the result is also affected by size of ABG at frequencies of 250, 500 and 1000 Hz. If Federici test is positive, there is a decrease in a difference between air and bone conduction when performing speech audiometry (performing of the test of 50 % numerals discrimination threshold by Kharshak), and if test is negative there is an increase in the difference. The Federici test is always negative when size of ABG is 40 dB and more at a frequency of 125 Hz.
Our results partially different from the literature. In particular, we have shown that a positive Federici test can be with a maximum size of ABG 35 dB at a frequency of 125 Hz and clarified in which cases that can be possible.
One of the promising directions of research is the diagnostic value of the Federici test in different middle ear pathology.