Audible in utero sound caused by the ultrasonic radiation force from a real-time scanner

Sabaratnam Arulkumaran, David G. Talbert, Margareta Nyman, Magnus Westgren, Hsu Tar Su, Shan S. Ratnam

Research output: Contribution to journalArticlepeer-review

Abstract

While investigating in utero sound levels during vibro-acoustic stimulation on the maternal abdomen it was noticed that noise level increased when the real-time ultrasonic scanner beam was directed at the sensing hydrophone. The noise was recorded and later analysed for frequency content and waveform. It appeared related to the scanning and frame rate frequencies of the scanner used. Sounds may originate from radiation pressure produced when the ultrasound beam is absorbed by tissue or reflected from bone or the metal hydrophone. This implies that although ultrasound cannot be heard per se, any modulation of its intensity will produce vibrations in the maternal tissues or reflecting structures such as skull bone, and especially stapes, malleus and incus, that would be heard as sound by the fetus. The intensity of the sound produced varied with orientation of the transducer beam and this may itself produce a stimulation. Based on our recordings, it was calculated that the fetus would hear a sound corresponding to 84dB noise pressure level in air.

Original languageEnglish
Pages (from-to)523-527
Number of pages5
JournalJournal of Obstetrics and Gynaecology Research
Volume22
Issue number6
Publication statusPublished - 1996

Keywords

  • Audible utero sound
  • Hydrophone
  • Radiation force
  • Transducer
  • Ultrasound

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