Morlet T, Goforth L, Hood L J, Ferber C, Duclaux R, Berlin C I
Kresge Hearing Research Laboratory of the South, LSU Medical Center, New Orleans, LA 70112, USA.
Hear Res. 1999 Aug;134(1-2):153-62. doi: 10.1016/s0378-5955(99)00078-7.
To study the functional development of the medial olivocochlear system, transient-evoked otoacoustic emission suppression experiments were conducted in 73 ears of 38 pre-term and 11 full-term neonates. The continuous contralateral stimulation was a broad band white noise, presented at 70 dB SPL. Efferent suppression was determined by subtracting the without-contralateral stimulation condition from the with-contralateral stimulation condition. Across this population, a mean suppression effect of contralateral stimulation on transient-evoked otoacoustic emissions was found, with most of the suppression effect observed after 8 ms. The amount of suppression is linearly, positively correlated with the conceptional age. In the subgroup of bilaterally tested neonates, the suppression of transient-evoked otoacoustic emissions is similar in the right ear and the left ear in subjects whose conceptional age is less than 36 weeks and significantly higher in the right ear than in the left ear in older neonates. This last observation was seen at frequencies where transient-evoked otoacoustic emission amplitudes became higher in the right ear than in the left ear as the conceptional age increased, a finding already reported in adults. This study shows that the functional adult pattern of the medial efferent system, probably involved in the detection of signals in noise such as speech sounds, seems to appear gradually in neonates and represents one of the several arguments in favor of functional auditory lateralization in humans, with a right ear advantage.
为研究内侧橄榄耳蜗系统的功能发育，对38例早产儿和11例足月儿的73只耳朵进行了瞬态诱发耳声发射抑制实验。连续对侧刺激为宽带白噪声，声压级为70 dB SPL。通过将对侧刺激条件下的结果减去无对侧刺激条件下的结果来确定传出抑制。在这一群体中，发现对侧刺激对瞬态诱发耳声发射有平均抑制作用，大部分抑制作用在8毫秒后观察到。抑制量与孕龄呈线性正相关。在双侧测试的新生儿亚组中，孕龄小于36周的受试者右耳和左耳的瞬态诱发耳声发射抑制相似，而年龄较大的新生儿右耳的抑制明显高于左耳。在随着孕龄增加瞬态诱发耳声发射振幅在右耳高于左耳的频率上观察到了这一最后的现象，这一发现已在成年人中报道过。本研究表明，内侧传出系统的成人功能模式可能参与了诸如语音等噪声中信号的检测，似乎在新生儿中逐渐出现，并且是支持人类功能性听觉侧化（右耳优势）的几个论据之一。
