Department of Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, United Kingdom.
Institute of Acoustics, Faculty of Physics, Adam Mickiewicz University, Poznań, Poland.
J Acoust Soc Am. 2019 May;145(5):2861. doi: 10.1121/1.5100620.
The ability to discriminate irregular from regular amplitude modulation was assessed using the "envelope regularity discrimination" test. The amount of irregularity was parametrically varied and quantified by an "irregularity index." Normative data were gathered for young subjects with normal audiometric thresholds. Parameters varied were the carrier and modulation frequencies, f and f, and the baseline modulation index, m. All tests were performed using a background threshold-equalizing noise. The main findings were (1) using f = 4000 Hz, f = 8 Hz, and m = 0.3, performance improved over the first two threshold runs and then remained roughly stable, and there was a high correlation between thresholds obtained at 80 dB sound pressure level (SPL) and at 20 dB sensation level; (2) using f = 8 Hz and m = 0.3 with a level of 80 dB SPL, thresholds did not vary significantly across f = 1000, 2000, and 4000 Hz; (3) using f = 8 Hz and f = 4000 Hz with a level of 80 dB SPL, thresholds did not vary significantly for m from 0.2 to 0.5; and (4) using m = 0.3 and f = 4000 Hz with a level of 80 dB SPL, thresholds improved with increasing f from 2 to 16 Hz. For all conditions, there was substantial individual variability, probably resulting from differences in "processing efficiency."
使用“包络规则辨别”测试评估辨别不规则与规则调幅的能力。通过“不规则指数”对不规则程度进行参数变化和量化。为听力阈值正常的年轻受试者收集了规范数据。变化的参数包括载波和调制频率 f 和 f 以及基线调制指数 m。所有测试均在背景阈值均衡噪声下进行。主要发现为：（1）使用 f=4000 Hz、f=8 Hz 和 m=0.3，表现随着前两次阈值运行而提高，然后大致保持稳定，在 80 dB 声压级 (SPL) 和 20 dB 感觉级获得的阈值之间存在高度相关性；（2）使用 f=8 Hz 和 m=0.3，80 dB SPL 水平，阈值在 f=1000、2000 和 4000 Hz 之间没有显著变化；（3）使用 f=8 Hz 和 f=4000 Hz，80 dB SPL 水平，m 从 0.2 到 0.5 时阈值没有显著变化；（4）使用 m=0.3 和 f=4000 Hz，80 dB SPL 水平，随着 f 从 2 增加到 16 Hz，阈值提高。对于所有条件，都存在大量的个体差异，可能是由于“处理效率”的差异所致。
