Eli5: what is ultrasound and what makes it “ultra”
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The device works by emitting very high frequency sound waves, which bounce back and can be turned into an image. The “sound” that it creates is much higher than humans can hear. “Ultra” means “beyond”. It’s beyond-sound.
the sounds doesn’t make it ultra? lol
“Ultra” here is a prefix meaning “higher than” – ultrasound is a sound wave with a frequency too high for humans to hear.
This high frequency makes it highly reflective in a way that lower frequency audible sound is not, so it can be used for medical imaging because it will reflect off of the density changes between different tissues in your body.
Lower frequency sound waves just punch right through you. Very low bass will even go through brick walls, and you may have experienced from some bad neighbors or shitty subwoofers over the years.
Ultrasound is just sound at very high frequencies – so high our ears can’t hear them. In fact that’s the definition – any sound above 20 kHz is classified as ultrasound. They’re used in medical scans, which are essentially sonar maps. The resolution will be something like the wavelength, so if you want to see an object in your body that’s 1 mm across, you need a wavelength of 1mm. Since the speed of sound in your body is ~1 km/s, that means you need a frequency of 1000 m/s divided by 0.001m, or about 1 MHz. That’s why you need to use ultrasound if you want to take useful scans of your body.
You’re aware of high pitch sounds and low pitch sounds.
A soprano singer can sing at a high pitch, and a base singer at a low pitch.
You’re also aware that we can only hear up to a certain pitch.
If a pitch goes even higher, than we can hear, it becomes ultra-sound.
It is simply an extremely high pitched sound, beyond the ability of the human ear to recognize.
“Ultra-” as a prefix means “above (a limit or range)”. The opposite is “infra-“, meaning “below (a limit or range)”.
“Ultrasound” means “sound waves *above* the range that we can hear”, and “infrasound” means “sound waves *below* the range that we can hear”.
Similarly: “ultraviolet” means “energy *above* the violet part of the visible spectrum”, while “infrared” means “energy *below* the red part of the visible spectrum”.
Ultrasound is sound of a higher frequency than the human ear is capable of hearing.
The prefix “ultra” means “beyond.” For example, the Spanish name for the region at the opposite end of the Mediterranean where the Kingdom of Jerusalem and Principality of Antioch were established was “Ultramar” (cognate to the more common French term “Outremer”). It means “Beyond the Sea.” The shade of blue called ultramarine gets its name from the fact that lapis lazuli used as pigment was imported from this region.
Similarly, ultrasound is “beyond sound.” Ultraviolet light is similarly higher frequency than violet and the human eye doesn’t have receptors for such a high frequency.
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