The aim of this paper is to show shifts in the language development of deaf and hard of hearing children over the last 30 years. The paper presents an overview of Western and Polish studies on education and language development in deaf children in terms of psycholinguistics. Perceptions of the perceptual and cognitive capabilities of such children must be subject to revision and continual methodological reflection due to rapidly changing variables, such as technological progress, social and cultural conditions of primary socialization and the aims of deaf education. Now that an increasing number of deaf children undergo cochlear implantation, and digital hearing aids can provide 70-75 dB of gain, thus enabling the children to spontaneously develop speech, many of them function in a bimodal environment of the sign and the speech. However, they perform at different levels of educational and developmental success. This paper elucidates the issues of language flexibility in and heterogenization of children using hearing aids or implants on a daily basis.