1. Audiology Unit, ORL Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
2. Pediatrics Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
3. Phoniatrics Unit, ORL Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
4. ORL Department, Abou El-Monagga Central Hospital, Ministry of Health, Cairo, Egypt