[Age-dependent electric response audiometry (ERA)-findings in correlation with speech development (author's transl)]

The occurrence of periods of speech-certainty and speech-uncertainty can be observed in normal as well as in children impaired with hearing, voice and speech defects. This behaviour of voice and speech development has not yet been explained by subjective pure-tone or speech audiometry. 19 normal children were grouped into four age populations according to electroglotto- and phonographic analysis. This collective was then examined by Electric Response Audiometry (ERA) at the frequencies of 0.5 kHz, 1.0 kHz, 2.0 kHz, and 4.0 kHz. Speech-certainty was observed at a mean age of 4.5 years (Group II) and 6.5 years (Group IV), whereas speech-uncertainty was found at a mean age of 2.5 years (Group I) and 5.5 years (Group III). The supraliminal ERA results of contralteral pickup were evaluated in amplitude and in behaviour of latency. Because of the variety of ERA-characteristics, the age-dependent and frequency-specific development of the acoustic system is figured by integration below the characteristics in the supraliminal range. The mathematical result shows two opposite regions as well as the "hearing dynamic" as at the "dynamic of the behaviour of latency": a low-frequency region of 0.5 and 1.0 kHz and a high-frequency region of 2.0 and 4.0 kHz. Evaluation of the electroglottograms following Fourier's analysis shows a typical amplitude spectrum at speech-certainty and at speech-uncertainty.