The fetal sound environment is now known to be rich and varied. Playback of tapes made from intrauterine recordings of sounds reveals some muffling, suggesting an attenuation of high-frequency sounds at the surface of the abdominal wall and during transmission through abdominal and uterine tissues and fluids. The present experiments show how the spectral features of synthesized musical sounds are altered once they reach the ear of the fetal sheep. Below 300 Hz, intrauterine sound pressure levels are nearly identical to those recorded outside the ewe. Between 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 above 600 Hz; this diminution could be perceived by the fetus as an altered timbre.

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