The Wonders of Ultrasound

Well - we were once again exposed to the wonders of ultrasound earlier today and witnessed the first pictures of our baby due somewhere around May 10. Pictures taken with sound - what an amazing concept! Here are some interesting factoids from Wikipedia that you may find interesting:

• Ultrasound is sound with a frequency greater than the upper limit of human hearing, this limit being approximately 20 kilohertz (20,000 hertz).
• Ultrasound is generally regarded as a "safe test" because it does not use ionising radiation as in x-rays, nuclear medicine, or CT. But it is a form of energy, and scans should only be performed for a suitable medical indication by trained operators. The biggest danger of ultrasound is often considered to be misdiagnosis by untrained operators.
• A common use of ultrasound is in range finding; this use is also called sonar. This works simiarly to radar: An ultrasonic pulse is generated in a particular direction. If there is an object in the path of this pulse, part or all of the pulse will be reflected back to the sender as an echo and can be detected. By measuring the difference in time between the pulse being transmitted and the echo being received, it is possible to determine how far away the object is.
• The dog whistle is used to call to a dog. It makes ultrasound at a frequency in the range of 16000 Hz to 22000 Hz that dogs can hear.
• It is well known that dolphins and some whales can hear ultrasound and have their own natural sonar system.

Some more interesting factoids were found at Howstuffworks. In ultrasound, the following events happen:

1. The ultrasound machine transmits high-frequency (1 to 5 megahertz) sound pulses into your body using a probe.
2. The sound waves travel into your body and hit a boundary between tissues (e.g. between fluid and soft tissue, soft tissue and bone).
3. Some of the sound waves get reflected back to the probe, while some travel on further until they reach another boundary and get reflected.
4. The reflected waves are picked up by the probe and relayed to the machine.
5. The machine calculates the distance from the probe to the tissue or organ (boundaries) using the speed of sound in tissue (5,005 ft/s or1,540 m/s) and the time of the each echo's return (usually on the order of millionths of a second).
6. The machine displays the distances and intensities of the echoes on the screen, forming a two dimensional image.

So yeah - interesting stuff and we are looking forward to revisiting the pictures/video of baby #3 in a couple weeks...and yes - we do know our future child's gender!

This may sound strange but knowing the gender in someways makes our baby more "real" and I'm curious if anyone else has experienced that? And now we have to decide how or if we should share this information? Seeing as we have two daughters already - some say the odds would be that we will have another daughter. Some say that every father needs a son and statistically it would make sense that we would have a boy! Frankly, both Wendy & I prior to going to the ultrasound admitted that if we were to have a boy we would be stepping into completely foreign territory - a little bit scary! Anyone care to place any wagers on gender, weight or birth date?