Audiometry

Hearing loss is decrease of capability to comprehend voices, which is one of the impairments with no evident signs and still a serious impairment. It is 28 times more common than phenyl ketonural (PKU), 8 times more than hypothyroidism, 5 times more than cystic fibrosis, and 20 times more than hemoglobiniopathy. Thereby, hearing loss is the most common congenital problem in infants.

Children with hearing loss who are lucky enough of being diagnosed before 6 months old have much better audio-lingual performance than those diagnosed after six months old. Any delay in diagnosing, treating, and rehabilitating children with hearing loss rapidly results in development of symptoms of hearing impairment in short run. Hearing screening is an essential, economic, and global practice that is aimed at timely diagnosis of hearing impairments in infants. The screening is performed on all infants in the world and based on audiometry results they are classified in “referral” and “acceptable” groups.

Infants’ audiometry is based on physiological and electro-physiological measures including Otoacoustic emission (OAE) and auditory brainstem (ABR) tests. The both techniques are functional and very successful tests for infant audiometry. However, despite effectiveness of the tests, they are costly and need expert attendance. Additionally, to have 50% hearing impairment screening coverage, we need 175 audiometer devices in IRAN, which is much more than what is actually available in the country. Given that the purpose of screening is not definite diagnosis of the problem; so that ascertaining if the person is classified in “acceptable” or “referral” groups suffices, the less expensive screening methods are quite welcomed.

Before being able to talk, human children communicate through voice making. Crying is one of the infant’s communication ways. It is the first experience of producing sound, which is articulated by larynx and mouth movement and audio feedback; a very fast process that is used to articulatephoneme.

A software pack to distinguish normal hearing and hearing loss, which can be used for infant auditory screening, was developed based on signal processing techniques, collecting infant’s crying signals, and determining different aspect of voice making through crying.