I’m making research about the possibility of fetus hearing perception (in terms of Hz).
We know that the future baby has a important preference to the mother’s voice. This voice arrive to the fetus by the spinal column and the sound is very high in tone.
Due to the fact that high tones are stimulating for human metabolism, fetus hears ultrasound and, from the other side, people older than 30-40 years are not yet able to hear more than 15-17 KHz, the question is:
Is it possible that the fetus has a specific Hz range hearing, able to listen to very high frequency like ultrasound and this capacity slowly disappears in perinatal life?
I’d like to listen to your opinion, that I consider very important for me.
According to 'Development of fetal hearing' by Peter G Hepper and B Sara Shahidullah, the high frequency range you are interested in was not considered in this study however it says that early in gestation 'none responded to the 1000 Hz and 3000 Hz tones'...so one can extrapolate...but it is all about hearing perception.
Here is an excellent article that discusses issues related to ultrasound:
http://www.ncbi.nlm.nih.gov/pubmed/22700164
[Obstetrical ultrasound: can the fetus hear the wave and ...
www.ncbi.nlm.nih.gov
1. Ultraschall Med. 2012 Jun;33(3):215-7. doi: 10.1055/s-0032-1312759. Epub 2012 Jun 14. [Obstetrical ultrasound: can the fetus hear the wave and feel the heat?].
So, if used when necessary and for short periods of exposure, there likely is no problem. Concerns can arise with long-term, repeated exposure....e.g.....using the ultrasound as a monitor for hours during labor, the fetus gets it through the fluid and tissues of the mother's body. Anything that can cause vibrations in the mother's body, in the frequency range of human hearing (20-20,000 Hz), if at a sufficient intensity, will excite the fetus's auditory sensory cells, once those cells are developed -- around the 20th week of gestation.
Hope this helps.
as per literature Ultrasound is a pressure wave with a frequency beyond (ultra) that detectable in the human auditory system.
The human ear can discern sound at roughly 20 - 20 000 cycles (hertz) per second. The frequencies of diagnostic ultrasound are roughly 1 - 10 megahertz (MHz) or 1 000 000 to 10 000 000 cycles per second. It is a form of energy and, as such, may have effects in tissues it traverses.
Any consequences occurring in living tissues secondary to an external influence are called biological effects or bioeffects. This term does not imply damage or harm.
The two major mechanisms for bioeffects are thermal and non-thermal.
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