Hall J W, Grose J H, Dev M B, Ghiassi S
Division of Otolaryngology, The University of North Carolina at Chapel Hill, 27599-7070, USA.
Ear Hear. 1998 Dec;19(6):429-33. doi: 10.1097/00003446-199812000-00004.
To determine the relation between the masking level difference (MLD) and the interaural time delay of the stimulus in children with a history of normal hearing and with a history of otitis media with effusion (OME).
MLDs for a 500 Hz pure tone presented in a 100 Hz-wide masking noise were determined as a function of the interaural delay of the masker (six interaural delays between -726 microsec and +998 microsec were examined). For the masker with zero interaural delay, the signal was presented either interaurally in-phase or 180 degrees out of phase. For the masker delay conditions, the signal was given the same interaural delay as the masker and then was inverted interaurally. All children had normal audiograms at the time of testing. Ten children had a history of normal hearing and seven children had a history of OME.
Similar to what has been found previously in adults, children with a history of normal hearing showed the maximum MLD (approximately 16 dB) for an interaural time delay of 0 microsec, with the MLD decreasing as a function of interaural time delay (by as much as 4 to 5 dB for the extreme delays). Children with a history of OME had significantly smaller MLDs than normal for the three smallest interaural delays but did not differ significantly from normal at the three largest interaural delays.
The form of the function relating masker interaural time delay to MLD magnitude is adult-like by age 6 yr. The function indicates a binaural advantage for the processing of sound near auditory midline. This advantage is less apparent in children having a history of OME.
确定有正常听力史及有中耳积液（OME）病史的儿童中，掩蔽级差（MLD）与刺激声的双耳时间延迟之间的关系。
在100Hz宽的掩蔽噪声中呈现500Hz纯音时的MLD，被确定为掩蔽器双耳延迟的函数（研究了-726微秒至+998微秒之间的六个双耳延迟）。对于双耳延迟为零的掩蔽器，信号以双耳同相或相差180度的方式呈现。对于掩蔽器延迟条件，信号给予与掩蔽器相同的双耳延迟，然后在双耳间反转。所有儿童在测试时听力图均正常。十名儿童有正常听力史，七名儿童有OME病史。
与先前在成人中发现的情况类似，有正常听力史的儿童在双耳时间延迟为0微秒时显示出最大MLD（约16dB），MLD随双耳时间延迟而降低（极端延迟时降低多达4至5dB）。有OME病史的儿童在三个最小的双耳延迟时MLD明显小于正常儿童，但在三个最大的双耳延迟时与正常儿童无显著差异。
到6岁时，掩蔽器双耳时间延迟与MLD大小之间的函数形式类似成人。该函数表明在处理听觉中线附近的声音时存在双耳优势。这种优势在有OME病史的儿童中不太明显。
