7.3 - Audible, Infrasonic and Ultrasonic Sounds
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Understanding Audible Sounds
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Today, we will explore the concept of audible sounds. Can anyone tell me what we mean by 'audible range'?
Is it the range of frequencies that we can hear?
Exactly, great job! The audible range is typically from 20 Hz to 20,000 Hz. That means we can hear sounds in that frequency range. Remember, sounds below and above this range are categorized differently.
So, who can hear these sounds if they're above or below that range?
Animals can often hear these sounds! For instance, dogs can hear ultrasonic sounds, while elephants can detect infrasonic sounds!
That's fascinating! What kind of sounds are we talking about when we say 'ultrasonic'?
Ultrasonic sounds are above 20,000 Hz, like the sounds made by bats for echolocation. It’s an incredible adaptation they use to navigate!
Can we use ultrasonic sounds in technology?
Absolutely! Ultrasonic sounds are utilized in medical imaging, cleaning, and even pest control! Remember: *Sounds that swim, help us see, human ears are just a key!*
Infrasonic Sounds
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Now, let’s discuss infrasonic sounds. Who can remind us what infrasonic sounds are?
They are sounds less than 20 Hz that we can't hear, right?
Correct! These are sounds that are below the audible range. Examples include the low rumbles from earthquakes. Why do you think they're important?
Maybe they can alert us to something happening, like an earthquake?
Exactly! Animals like elephants use infrasonic sounds to communicate over large distances. It helps them stay aware of their surroundings.
That's really cool! I didn't know animals could hear such low frequencies!
Yes, and it’s a great example of how different species adapt to their environments! Remember: *Infrasonics are silent roars, in nature's show, they play the scores!*
Ultrasonic Sounds
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Let’s dive into ultrasonic sounds. Who can define them?
Sounds that are above 20,000 Hz, right?
Yes! And what are some practical applications of ultrasonic sounds?
Medical imaging, like ultrasounds!
And cleaning things using ultrasonic waves, right?
Correct! Ultrasonic waves are used in various industries to clean delicate instruments without damage. They’re efficient and effective. Mnemonic time: *If it’s above twenty K, ultrasound will find its way!*
This is so interesting! I can't believe how versatile sound can be.
Introduction & Overview
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Quick Overview
Standard
The section defines three categories of sound based on frequency: audible sounds (20 Hz – 20,000 Hz), which humans can hear; infrasonic sounds (less than 20 Hz), such as those produced by earthquakes; and ultrasonic sounds (more than 20,000 Hz), which are used in applications like bats' echolocation and medical imaging.
Detailed
Audible, Infrasonic and Ultrasonic Sounds
In this section, we explore the classification of sound based on its frequency. Sound can be categorized into three distinct ranges:
1. Audible Sounds: The range detectable by human ears is between 20 Hz and 20,000 Hz. This range encompasses the sounds we commonly hear in our daily lives.
2. Infrasonic Sounds: These sounds have frequencies less than 20 Hz, which are inaudible to human ears but can be sensed by some animals and are typically created by phenomena such as earthquakes or by certain animals like elephants.
3. Ultrasonic Sounds: With frequencies above 20,000 Hz, these sounds are also beyond human hearing but can be detected by animals such as bats. Ultrasonic sounds find significant applications in technological fields, including medical imaging and cleaning.
Understanding these categories of sound is crucial as they play important roles in various natural and technological processes.
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Audible Range
Chapter 1 of 3
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Chapter Content
● Audible Range: 20 Hz – 20,000 Hz (can be heard by humans).
Detailed Explanation
The audible range refers to the frequencies of sound that humans can hear. It is between 20 Hz (which is a very low bass sound) and 20,000 Hz (which is a high-pitched sound). Sounds within this frequency range, such as the music you listen to or the voice of a friend, can be perceived by the human ear.
Examples & Analogies
Think of the audible range like a spectrum of colors. Just as we can see a variety of colors within the rainbow, we can hear a variety of sounds in our audible range. Low notes in music are like dark colors, and high notes are like bright colors.
Infrasonic Sounds
Chapter 2 of 3
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Chapter Content
● Infrasonic: Less than 20 Hz (e.g., earthquakes, elephants).
Detailed Explanation
Infrasonic sounds are those with frequencies below 20 Hz. These sounds are too low for humans to hear, but many animals, especially some large mammals like elephants, can perceive them. Infrasonic waves can also occur during natural events, such as earthquakes, where the vibrations are felt rather than heard.
Examples & Analogies
Imagine standing in a large room where someone is playing very deep bass music. You might not hear the very low notes, but you can feel the vibrations through your body. That's similar to how infrasonic sounds work — we might not hear them, but their effects can be felt or detected in other ways.
Ultrasonic Sounds
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Chapter Content
● Ultrasonic: More than 20,000 Hz (e.g., bats, dog whistles, medical imaging).
Detailed Explanation
Ultrasonic sounds are those with frequencies higher than 20,000 Hz. These sounds are also inaudible to humans but are used extensively in nature and technology. Animals like bats use ultrasonic sounds for echolocation, while dog whistles produce sounds that dogs can hear but humans cannot. Medical imaging technologies, such as ultrasound, also rely on ultrasonic waves to create images of the inside of the body.
Examples & Analogies
Picture a bat flying in the night sky. It emits ultrasonic sounds that bounce off objects and return to it, allowing it to 'see' its surroundings in complete darkness. This is similar to how sonar works in submarines, using high-frequency sounds to detect objects underwater. For humans, think of how doctors use ultrasound to see a baby developing in the womb, employing sounds we can't hear to visualize and monitor health.
Key Concepts
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Audible Sound: The range of sound we can hear, between 20 Hz and 20,000 Hz
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Infrasonic Sound: Sounds below 20 Hz, inaudible to humans, like earthquakes.
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Ultrasonic Sound: Sounds above 20,000 Hz, used in applications such as medical imaging.
Examples & Applications
Audible sounds include music, speech, and everyday noises we can hear.
Infrasonic sounds can be produced by natural events like earthquakes or large machinery.
Ultrasonic sounds are used in medical ultrasound imaging and pest control devices.
Memory Aids
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Rhymes
Audible sounds we can hear, Infra's too low, Ultras appear!
Stories
Once there was a sound that everyone heard, it danced in the air and wasn't absurd. It played in the range of twenty to twenty thousand, but below that, it faded — it wasn't so loud. And above it, a group of bats flew around, making sounds so high that no human could sound. But some animals said, 'We can hear them clear!' — for in the world of sound, many can cheer!
Memory Tools
A fun way to remember the ranges: 'A.I.U.' - Audible (20 Hz - 20,000 Hz), Infrasonic (<20 Hz), Ultrasonic (>20,000 Hz).
Acronyms
Remember 'A-I-U'
for Audible
for Infrasonic
and U for Ultrasonic!
Flash Cards
Glossary
- Audible Sound
Sounds within the frequency range of 20 Hz to 20,000 Hz which can be heard by humans.
- Infrasonic Sound
Sounds with frequencies less than 20 Hz that are not audible to humans.
- Ultrasonic Sound
Sounds with frequencies greater than 20,000 Hz that are also not audible to humans.
Reference links
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