Gorga M P, Norton S J, Sininger Y S, Cone-Wesson B, Folsom R C, Vohr B R, Widen J E, Neely S T
Multicenter Consortium on Identification of Neonatal Hearing Impairment, Seattle, Washington, USA.
Ear Hear. 2000 Oct;21(5):400-24. doi: 10.1097/00003446-200010000-00007.
DPOAEs were measured in 2348 well babies without risk indicators, 353 well babies with at least one risk indicator, and 4478 graduates of neonatal intensive care units (NICUs). DPOAE and noise levels were measured at f2 frequencies of 1.0, 1.5, 2.0, 3.0, and 4.0 kHz, and for primary levels (L1/L2) of 65/50 dB SPL and 75/75 dB SPL. Measurement-based stopping rules were used such that a test did not terminate unless the response was at least 3 dB above the mean noise floor + 2 SDs (SNR) for at least four of five test frequencies. The test would terminate, however, if these criteria were not met after 360 sec. Baby state, test environment, and other test factors were captured at the time of each test.
DPOAE levels, noise levels and SNRs were similar for well babies without risk indicators, well babies with risk indicators, and NICU graduates. There was a tendency for larger responses at f2 frequencies of 1.5 and 2.0 Hz, compared with 3.0 and 4.0 kHz; however, the noise levels systematically decreased as frequency increased, resulting in the most favorable SNRs at 3.0 and 4.0 kHz. Response levels were least and noise levels highest for an f2 frequency of 1.0 kHz. In addition, test time to achieve automatic stopping criteria was greatest for 1.0 kHz. With the exception of "active/alert" and "crying" babies, baby state had little influence on DPOAE measurements. Additionally, test environment had little impact on these measurements, at least for the environments in which babies were tested in this study. However, the lowest SNRs were observed for infants who were tested in functioning isolettes. Finally, there were some subtle age affects on DPOAE levels, with the infants born most prematurely producing the smallest responses, regardless of age at the time of test.
DPOAE measurements in neonates and infants result in robust responses in the vast majority of ears for f2 frequencies of at least 2.0, 3.0 and 4.0 kHz. SNRs decrease as frequency decreases, making the measurements less reliable at 1.0 kHz. When considered along with test time, there may be little justification for including an f2 frequency at 1.0 kHz in newborn screening programs. It would appear that DPOAEs result in reliable measurements when tests are conducted in the environments in which babies typically are found. Finally, these data suggest that babies can be tested in those states of arousal that are most commonly encountered in the perinatal period.
1）描述新生儿和婴儿在广泛频率范围以及两种刺激水平下的畸变产物耳声发射（DPOAEAE）水平、噪声水平和信噪比（SNR）。2）描述这些DPOAE测量值与年龄、测试环境、婴儿状态和测试时间之间的关系。
对2348名无风险指标的健康婴儿、353名至少有一项风险指标的健康婴儿以及4478名新生儿重症监护病房（NICU）毕业生进行了DPOAE测量。在1.0、1.5、2.0、3.0和4.0 kHz的f2频率下，以及65/50 dB SPL和75/75 dB SPL的初级水平（L1/L2）下测量DPOAE和噪声水平。采用基于测量的停止规则，即除非在五个测试频率中的至少四个频率上，响应至少比平均本底噪声+2标准差（SNR）高3 dB，否则测试不会终止。然而，如果在360秒后未满足这些标准，测试将终止。每次测试时记录婴儿状态、测试环境和其他测试因素。
无风险指标的健康婴儿、有风险指标的健康婴儿和NICU毕业生的DPOAE水平、噪声水平和SNR相似。与3.0和4.0 kHz相比，在1.5和2.0 Hz的f2频率下有更大反应的趋势；然而，噪声水平随着频率增加而系统性降低，导致在3.0和4.0 kHz时SNR最有利。对于1.0 kHz的f2频率，响应水平最低，噪声水平最高。此外，达到自动停止标准的测试时间在1.0 kHz时最长。除了“活跃/警觉”和“哭闹”的婴儿外，婴儿状态对DPOAE测量影响很小。此外，测试环境对这些测量影响很小，至少对于本研究中婴儿进行测试的环境是这样。然而，在功能保温箱中测试的婴儿观察到最低的SNR。最后，年龄对DPOAE水平有一些细微影响，无论测试时的年龄如何，早产程度最高的婴儿产生的反应最小。
对于至少2.0、3.0和4.0 kHz的f2频率，新生儿和婴儿的DPOAE测量在绝大多数耳朵中产生强烈反应。SNR随着频率降低而降低，使得在1.0 kHz时测量不太可靠。考虑到测试时间，在新生儿筛查项目中纳入1.0 kHz的f2频率可能没有什么道理。当在婴儿通常所在的环境中进行测试时，DPOAE似乎能产生可靠的测量结果。最后，这些数据表明可以在围产期最常见的觉醒状态下对婴儿进行测试。
