FETAL MUSIC PERCEPTION - THE ROLE OF SOUND-TRANSMISSION

The fetal sound environment is now known to be rich and varied. Playba ck of tapes made from intrauterine recordings of sounds reveals some m uffling, suggesting an attenuation of high-frequency sounds at the sur face of the abdominal wall and during transmission through abdominal a nd uterine tissues and fluids. The present experiments show how the sp ectral features of synthesized musical sounds are altered once they re ach the ear of the fetal sheep. Below 300 Hz, intrauterine sound press ure levels are nearly identical to those recorded outside the ewe. Bet ween 315 and 2500 Hz, the attenuation increases at a rate of 5 dB per octave. Spectral analyses of trumpet and flugelhorn sounds recorded in utero show a marked diminution in sound pressure level in partials ab ove 600 Hz; this diminution could be perceived by the fetus as an alte red timbre.