الفهرس 
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Abstract
Hearing impairment is the most frequent sensory deficit in the human population and can occur at any age. Hearing loss ranges from mild to severe, or profound. Low frequencies are often differently affected from high frequencies; impairment also differs from patient to patient, even when of equal genetic origin (Oshima et al., 2010).
There is an integrative relationship among hearing, speech, language and communication, so hearing loss in children varies considerably in the extent to which it impacts these areas of development. The impact on communication is the major handicapping influence of hearing loss. If communication is not affected, hearing loss may have little or no impact on a child’s life (Justice, 2006).
Children suffering from hearing loss usually present with delayed language development, scholastic underachievement, behavioral, intellectual and social problems (Kotby et al., 2008). Early fitting of infants with suitable amplification devices by the age of 6 months has favorable effect on development of their speech and language (Parving, 1999).
Hearing aids come in a variety of styles but can be placed into two general categories: behind-the-ear styles (BTE) and custom products that fit into the ear canal. Custom products come in a variety of sizes—in-the-ear (ITE), in-the-canal (ITC), or completely-in-the-canal (CIC)—but all are similar in that the components fit into a custom shell fabricated from a mold of the individual’s ear. BTEs have been available since the 1950s, whereas the custom products have been widely available since the late 1970s for the larger styles and the late 1980s for the CICs. Each style has benefits and limitations (Paul and Whitelaw, 2011).
Implantable middle ear hearing devices or active middle ear implants were developed in an effort to improve the limitations of traditional hearing aids. The last few years have seen significant advances in this technology with the emergence of several new devices, including fully implantable prostheses (Bassim and Fayad, 2010). Many problems that patients with conventional hearing aids report, such as acoustic feedback, occlusion, and irritation of the outer ear canal, are avoided (Wagner et al., 2010). In comparison to conventional hearing aids implantable hearing aids are a promising tool to give a substantial reduction of distortion and thus an improved sound quality and speech recognition (Leuwer and Muller, 2005).
For profoundly deaf people, amplification alone is inadequate for restoring hearing if the organ of Corti is no longer functioning, acoustic stimulation does not produce a sensation of hearing, so it becomes necessary to restore hearing by direct electrical stimulation of the auditory nerve. Sounds are converted into electrical signals, as in a conventional hearing aid, but then, instead of driving a transducer to produce a more intense acoustic signal, they stimulate the auditory nerve directly via a number of electrodes implanted in the cochlea (Clark, 2004). A portion of the cochlear implant device is surgically implanted into the cochlea and the remaining portion worn externally like a hearing aid (Miyamoto, 1995).
Cochlear implants have shown tremendous promise in restoring auditory information to deaf children and concomitant improvements in speech recognition and production (Quittner et al., 2004)
Over the past 2 decades, there have been significant improvements in the development of hearing aids and cochlear implants to provide deaf patients with important auditory cues for both speech comprehension and their aural environments (Tan et al., 2008).Language delay can affect both children with hearing aids and children with cochlear implants. Children who use cochlear implants have been stated to have better language and vocabulary development when compared to children who use hearing aids (Geers and Moog, 1994). Children who wear hearing aids and have a significant hearing loss can have difficulty in all areas of language such as pragmatics, syntax and more importantly, vocabulary (Tye-Murray, 2004).