Ultrasonics

Hello, Beauty.

This is one of the many images created by a strange machine you and your mother were exposed to for over an hour.

Science is a strange thing. Some people develop a certainty about science and technology that True Believers used to reserve for God and religion.

We're so naturally inquisitive but also (I think) sometimes a bit too eager to seek certainty in all things.  In fact, sometimes we grab at it like straws that might hold us. Sometimes it's difficult for the technically-minded to admit their own lack of knowledge.

Take the young (as yet unlicensed) technician the hospital allowed to perform the ultrasound.

After half an hour of running the ultrasonic wand around your mother's gooey belly and after poking at mom to get you to move so the technician could get the photo's SHE wanted, I started getting aggravated. (I'm hoping to work on this unflattering quality over the next few months before you get here.) Watching her bounce the plastic against your mother's belly, I began to wonder if there might be some effects of the jostling OR the ultrasound itself.

So I asked the technician if you could hear any of this. (I should explain that I was wondering if even at levels that are ULTRA (or above) our terrestrial hearing, if perhaps in the amniotic fluid in which you currently swim, if perhaps, the ultrasound might be received by your developing ears differently. You're sort of like a fabulous sea creature right now!)

The technician looked at me with the bemused patience of most technicians who don't like people questioning what they're doing. (Especially while they're DOing it!) "Oh, no," she said, "ultrasound means that it's outside our range of hearing. And the baby's too."

Having read articles about the possible effects on whales and dolphins (some people believe that ultrasonic frequencies used by submarines and the defense industry can disorient these sea creatures who can pick up those signals and cause them to become disoriented and become stranded on shore (some even think it causes bleeding in the brain)), I wasn't completely convinced. (By the time you get around to reading this; that last statement probably won't surprise you.)

But here is what I found from New Scientist magazine from more than decade ago:

Ultrasound examinations during pregnancy expose the fetus to a sound as loud as that made by a subway train coming into a station, say US researchers. But doctors do not think the experience causes a baby any lasting harm.

Neither adults nor fetuses can hear ultrasound waves because they vibrate at too high a frequency for our ears to detect them. But James Greenleaf, Paul Ogburn and Mostafa Fatemi of the Mayo Foundation in Rochester, Minnesota, investigated the possibility that ultrasound could cause secondary vibrations in a woman's uterus.

Ultrasound machines generate sound waves in pulses lasting less than one ten thousandth of a second. Pulses are used because a continuous soundwave could generate too much heat in the tissue being examined. The Mayo team predicted that the pulsing would translate into a "tapping" effect.

They listened in by placing a tiny hydrophone inside a woman's uterus while she was undergoing an ultrasound examination. Sure enough, they picked up a hum at around the frequency of the tapping generated when the ultrasound is switched on or off. The sound was similar to the highest notes on a piano.

Theoretical consequences

When the ultrasound probe pointed right at the hydrophone, it registered 100 decibels, as loud as a subway train coming into a station. "It's fairly loud if the probe is aimed right at the ear of the fetus," says Greenleaf.

Fredic Frigoletto, chief of maternal fetal medicine at Massachusetts General Hospital in Boston, says doctors should be careful not to point the ultrasound probe directly at a fetus's ear unless there is a particular reason to suspect facial or cranial abnormalities. "Then the benefits significantly outweigh any theoretical consequences," he says.

Fatemi presented the team's research at the annual meeting of the Acoustical Society of America in Fort Lauderdale, Florida.

Perhaps by the time you are born, we'll have learned more about this, but I doubt it.

And long after you're born, I think there will be people like this young technician who believe anything they've been told.

My hope for you is that you develop a healthy skepticism. Not frozen by indecision or fear in moving forward with smart thinking, but open to inquiry. The history of human beings is filled with those who would question what they've been taught and are able to discover some new idea or way of thinking.

For the moment, I think we'll think a bit more about how often you have to listen to those subway trains when you're in your mother's womb.