Introduction:
The effect of SARS-CoV-2 on hearing has not been thoroughly examined. Factors limiting hearing tests in COVID-19 patients are hygiene requirements and the need to use specialized equipment. The objective of the study was to assess changes in hearing thresholds between diagnosis of COVID-19 and convalescence using a mobile app.

Material and methods:
Patients with mild to moderate COVID-19 symptoms, who were isolating at home were enrolled in the study between 1 September 2020 and 31 January 2021. Subjects answered an online medical survey and self-assessed hearing thresholds using the Hearing Test^TM mobile app (e-audiologia.pl). These procedures were done twice, once at the time of diagnosis and again 2 weeks after convalescence.

Results:
A total of 67 subjects were found eligible for the study. At most frequencies the patients’ hearing did not differ between the first and second examinations; however, for 4 kHz, a statistically significant improvement in the hearing threshold was found (p = 0.05). Survey review revealed noticeable improvement (p = 0.001) over time in smell, taste, and nasal congestion.

Conclusions:
It seems that SARS-CoV-2 infection caused a transient and selective (at 4 kHz) hearing impairment in patients who had had mild to moderate infection. The results suggest that as olfactory function returns after COVID-19, an improvement in hearing can be expected. Solutions based on mobile technology are useful for monitoring the hearing of patients in a pandemic.