Marshall L, Hanna T E, Wilson R H
Naval Submarine Medical Research Laboratory Groton, CT, USA.
J Speech Hear Res. 1996 Aug;39(4):687-96. doi: 10.1044/jshr.3904.687.
Audibility thresholds for a 1000-Hz sinusoid were measured with a standard clinical (CLIN) procedure and a two-interval, forced-choice (2IFC) adaptive procedure bracketing 79% correct. Both used 2- and 5-dB step sizes in quiet and in a continuous, broadband noise background. Clinical thresholds were from 2 to 4 dB higher than 2IFC thresholds, depending on the condition. Step size had a larger effect on the CLIN thresholds than the 2IFC thresholds. For the CLIN procedure, thresholds with a 2-dB step size were 1.4 dB lower than with a 5-dB step size. For the 2IFC procedure, thresholds with a 2-dB step size were 0.8 dB higher than with a 5-dB step size. Reliability, as measured by the intrasubject standard deviation, was better for the 2IFC than for the CLIN procedure and better in noise than in quiet. Reliability was unaffected by step size. Adding extra trials to the 2IFC adaptive track decreased the variability across threshold estimates, but more for the noise background than the quiet background. The efficiency of the 2IFC procedure was fairly constant across track length in noise, but decreased for longer track lengths in quiet. In both quiet and noise backgrounds, CLIN procedures were much more efficient than 2IFC procedures.
采用标准临床（CLIN）程序和正确率为79%的双间隔、强制选择（2IFC）自适应程序测量了1000赫兹正弦波的听阈。两者在安静环境以及连续宽带噪声背景下均采用了2分贝和5分贝的步长。临床阈值比2IFC阈值高2至4分贝，具体取决于条件。步长对CLIN阈值的影响大于对2IFC阈值的影响。对于CLIN程序，2分贝步长的阈值比5分贝步长的阈值低1.4分贝。对于2IFC程序，2分贝步长的阈值比5分贝步长的阈值高0.8分贝。通过受试者内标准差衡量的可靠性，2IFC程序比CLIN程序更好，且在噪声环境中比在安静环境中更好。可靠性不受步长影响。在2IFC自适应轨迹中增加额外试验可降低阈值估计的变异性，但在噪声背景下比在安静背景下降低得更多。2IFC程序的效率在噪声环境中随轨迹长度相当恒定，但在安静环境中对于较长轨迹长度会降低。在安静和噪声背景下，CLIN程序都比2IFC程序高效得多。
