Demany L, Semal C
Laboratoire de Psychoacoustique, Université de Bordeaux II, France.
Percept Psychophys. 1990 Nov;48(5):436-44. doi: 10.3758/bf03211587.
Five experiments on the identifiability of synthetic vowels masked by wideband sounds are reported. In each experiment, identification thresholds (signal/masker ratios, in decibels) were measured for two versions of four vowels: a vibrated version, in which FO varied sinusoidally around 100 Hz; and a steady version, in which F0 was fixed at 100 Hz. The first three experiments were performed on naive subjects. Experiment 1 showed that for maskers consisting of bursts of pink noise, vibrato had no effect on thresholds. In Experiment 2, where the maskers were periodic pulse trains with an F0 randomly varied between 120 and 140 Hz from trial to trial, vibrato slightly improved thresholds when the sound pressure level of the maskers was 40 dB, but had no effect for 65-dB maskers. In Experiment 3, vibrated rather than steady pulse trains were used as maskers; when these maskers were at 40 dB, the vibrated versions of the vowels were slightly less identifiable than their steady versions; but, as in Experiment 2, vibrato had no effect when the maskers were at 65 dB. Experiment 4 showed that the unmasking effect of vibrato found in Experiment 2 disappeared in subjects trained in the identification task. Finally, Experiment 5 indicated that in trained listeners, vibrato had no influence on identification performance even when the maskers and the vowels had synchronous onsets and offsets. We conclude that vibrating a vowel masked by a wideband sound can affect its identification threshold, but only for tonal maskers and in untrained listeners. This effect of vibrato should probably be considered as a Gestalt phenomenon originating from central auditory mechanisms.
本文报告了五项关于宽带声音掩盖下合成元音可识别性的实验。在每项实验中，针对四个元音的两个版本测量了识别阈值（以分贝为单位的信号/掩蔽比）：一个是振动版本，其中基频（FO）在100Hz左右呈正弦变化；另一个是稳定版本，其中F0固定在100Hz。前三项实验是在未受过训练的受试者身上进行的。实验1表明，对于由粉红噪声突发组成的掩蔽音，颤音对阈值没有影响。在实验2中，掩蔽音是周期性脉冲序列，其F0在每次试验中随机在120Hz至140Hz之间变化，当掩蔽音的声压级为40dB时，颤音略微改善了阈值，但对于65dB的掩蔽音则没有影响。在实验3中，使用振动而非稳定的脉冲序列作为掩蔽音；当这些掩蔽音为40dB时，元音的振动版本比其稳定版本的可识别性略低；但是，与实验2一样，当掩蔽音为65dB时，颤音没有影响。实验4表明，在接受识别任务训练的受试者中，实验2中发现的颤音解掩蔽效应消失了。最后，实验5表明，在训练有素的听众中，即使掩蔽音和元音具有同步的起始和结束，颤音对识别性能也没有影响。我们得出结论，振动被宽带声音掩盖的元音会影响其识别阈值，但仅适用于音调掩蔽音且针对未受过训练的听众。颤音的这种效应可能应被视为一种源自中枢听觉机制的格式塔现象。
