Hepper P G, Shahidullah B S
Queen's University of Belfast, Northern Ireland, School of Psychology.
Arch Dis Child Fetal Neonatal Ed. 1994 Sep;71(2):F81-7. doi: 10.1136/fn.71.2.f81.
Previous research has revealed that the human fetus responds to sound, but to date there has been little systematic investigation of the development of fetal hearing. The development of fetal behavioural responsiveness to pure tone auditory stimuli (100 Hz, 250 Hz, 500 Hz, 1000 Hz, and 3000 Hz) was examined from 19 to 35 weeks of gestational age. Stimuli were presented by a loudspeaker placed on the maternal abdomen and the fetus's response, a movement, recorded by ultrasound. The fetus responded first to the 500 Hz tone, where the first response was observed at 19 weeks of gestational age. The range of frequencies responded to expanded first downwards to lower frequencies, 100 Hz and 250 Hz, and then upwards to higher frequencies, 1000 Hz and 3000 Hz. At 27 weeks of gestational age, 96% of fetuses responded to the 250 Hz and 500 Hz tones but none responded to the 1000 Hz and 3000 Hz tones. Responsiveness to 1000 Hz and 3000 Hz tones was observed in all fetuses at 33 and 35 weeks of gestational age, respectively. For all frequencies there was a large decrease (20-30 dB) in the intensity level required to elicit a response as the fetus matured. The observed pattern of behavioural responsiveness reflects underlying maturation of the auditory system. The sensitivity of the fetus to sounds in the low frequency range may promote language acquisition and result in increased susceptibility to auditory system damage arising from exposure to intense low frequency sounds.
先前的研究表明，人类胎儿对声音有反应，但迄今为止，对胎儿听力发育的系统研究较少。研究了孕19至35周时胎儿对纯音听觉刺激（100赫兹、250赫兹、500赫兹、1000赫兹和3000赫兹）的行为反应发育情况。刺激由放置在孕妇腹部的扬声器发出，胎儿的反应即胎动，通过超声记录。胎儿首先对500赫兹的音调做出反应，在孕19周时观察到首次反应。对声音做出反应的频率范围首先向下扩展到较低频率，即100赫兹和250赫兹，然后向上扩展到较高频率，即1000赫兹和3000赫兹。在孕27周时，96%的胎儿对250赫兹和500赫兹的音调有反应，但对1000赫兹和3000赫兹的音调无反应。在孕33周和35周时，分别在所有胎儿中观察到对1000赫兹和3000赫兹音调的反应。随着胎儿成熟，对于所有频率，引发反应所需的强度水平大幅降低（20 - 30分贝）。观察到的行为反应模式反映了听觉系统的潜在成熟。胎儿对低频范围内声音的敏感性可能促进语言习得，并导致因接触强烈低频声音而增加听觉系统受损的易感性。
