It may be because of too long time usr of headphones. Please tell them not to use headphones but they can use speaker of mobile to talk. You can give tham Tab. NEUROBION FORT , Once a day for 15 days.
Next Steps
if no improvement, please consult near by ENT specialist . He will do Audiogram for the perfect diagnosis of the cause of sound in ear.
Health Tips
Do meditation for 15 to 20 minutes. Brahmakumaris Guided meditation videos are available on youtube.