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10.6 - Audible and Inaudible Sounds

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Understanding Audible Frequencies

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Teacher
Teacher

Alright class, today we're exploring what sounds we can hear! Can anyone tell me the range of frequencies our ears can detect?

Student 1
Student 1

Is it from 0 to 100 Hz?

Teacher
Teacher

Good guess, but it's actually from 20 Hz to 20,000 Hz! We call these frequencies 'audible sounds.' Remember, 20 is like the starting line. Let's keep that in mind.

Student 2
Student 2

What happens to sounds below 20 Hz?

Teacher
Teacher

Great question! Sounds below 20 Hz are called 'inaudible' because we can't hear them. Let’s remember: Less than 20 = Inaudible!

Student 3
Student 3

What uses low-frequency sounds have?

Teacher
Teacher

These low-frequency sounds can alert us to things like earthquakes. So, we can't hear them, but they can certainly affect us!

Student 4
Student 4

What sounds are above 20,000 Hz?

Teacher
Teacher

That's the higher end of our range, often referred to as ultrasound. It’s not just high-pitched sounds; it's a device used in medical technology to create images of the body. We call that medical imaging!

Teacher
Teacher

In summary, the range of frequencies we can hear is crucial for communication and understanding our environment. Remember: Dogs can hear sounds even above 20,000 Hz, which humans cannot!

Inaudible Sounds and Their Implications

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Teacher
Teacher

Continuing from where we left off, let's talk more about those inaudible sounds. What could that mean for animals, like dogs?

Student 1
Student 1

They can hear things we can't! Like those high-pitched whistles the police use?

Teacher
Teacher

Exactly! This makes sense because dogs have a wider hearing range. They can detect sounds that signal danger or calls for them. Can you think of other applications of high-frequency sounds?

Student 2
Student 2

What about medical uses?

Teacher
Teacher

Right again! Ultrasound frequencies can be used for images of babies in the womb, known as prenatal ultrasound, which operates beyond 20,000 Hz.

Student 3
Student 3

So, there are both harmful and helpful uses for these frequencies?

Teacher
Teacher

Exactly! Some sound frequencies may not be noticeable to us, but they can interact with our environment significantly—positively and negatively. Remember: Lower than 20 Hz = Inaudible, Higher than 20 kHz = Inaudible!

Teacher
Teacher

To summarize, while we engage with many sounds daily that we can hear, there’s a whole world of inaudible frequencies performing their own functions, both in animals and technology!

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

This section explores the range of sound frequencies detectable by the human ear, defining audible sounds as those between 20 Hz to 20,000 Hz, and highlighting inaudible sounds beyond these limits.

Standard

In this section, we learn about the limitations of human hearing regarding sound frequencies. Sounds below 20 Hz are termed inaudible, as are those above 20 kHz. The section highlights the implications of these ranges in everyday life, such as dogs hearing high-frequency sounds and the use of ultrasound in medical diagnostics.

Detailed

Audible and Inaudible Sounds

The section outlines the range of frequencies that the human ear can detect, which lies between approximately 20 Hz and 20,000 Hz (20 kHz). Any sound with a frequency below 20 Hz is considered inaudible and is often beyond human perception. These low frequency sounds can include rudimentary natural phenomena like earthquakes. Conversely, high frequency sounds exceeding 20 kHz, such as ultrasonic waves, also fall outside human auditory capability. Interestingly, certain animals, particularly dogs, can detect higher frequencies, making them responsive to sounds inaudible to humans, such as police whistles designed to be heard by canine companions.

Ultrasound technology, which functions at frequencies higher than 20,000 Hz, is crucial in medical imaging and diagnostics, providing a means to visualize internal bodily structures non-invasively. Understanding these limits not only enhances our awareness of sound but also aids in developing technologies that utilize inaudible frequencies for various applications.

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Audio Book

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The Range of Audible Frequencies

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We know that we need a vibrating body for the production of sound. Can we hear the sound of all vibrating bodies? The fact is that sounds of frequencies less than about 20 vibrations per second (20 Hz) cannot be detected by the human ear. Such sounds are called inaudible. On the higher side, sounds of frequencies higher than about 20,000 vibrations per second (20 kHz) are also not audible to the human ear. Thus, for human ear, the range of audible frequencies is roughly from 20 to 20,000 Hz.

Detailed Explanation

What this means is that there are sounds we cannot hear because they fall outside the limits of our hearing ability. Sounds below 20 Hz are considered too low in frequency for us to detect, while those above 20,000 Hz are too high. Thus, humans can hear sounds within a specific range, which is from 20 Hz to 20 kHz.

Examples & Analogies

Think of it like a radio that can only pick up certain frequencies. If a station broadcasts on a frequency that your radio doesn't support, you won't be able to hear it. Similarly, sound waves below or above the limits of our hearing range won't be detected by our ears.

Animal Hearing Differences

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Some animals can hear sounds of frequencies higher than 20,000 Hz. Dogs have this ability. The police use high frequency whistles which dogs can hear but humans cannot.

Detailed Explanation

Different animals have different hearing abilities. For example, dogs can hear much higher frequencies than humans can. This is why police use special whistles that can alert dogs, as humans will not be able to hear those sounds.

Examples & Analogies

Imagine a person wearing earplugs that block out all high-frequency sounds. The person may hear someone talking to them, but they won't hear the whistle of a dog trainer. Similarly, dogs can hear the whistle while humans cannot.

Ultrasound Applications

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The ultrasound equipment, familiar to us for investigating and tracking many medical problems, works at frequencies higher than 20,000 Hz.

Detailed Explanation

Ultrasound is commonly used in medicine for imaging. This technology operates at frequencies above 20 kHz, allowing health practitioners to visualize internal organs and tissues without invasive procedures. The factor that makes it effective is that these high-frequency sound waves can bounce off tissues, creating an image.

Examples & Analogies

Think of ultrasound as using sonar, similar to how submarines locate objects underwater by sending out sound waves. Instead of detecting fish, ultrasound in medicine helps visualize organs in a human body to diagnose conditions.

Definitions & Key Concepts

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Key Concepts

  • Audible Frequencies: The human hearing range is typically considered to be between 20 Hz and 20,000 Hz.

  • Inaudible Frequencies: Sounds below 20 Hz and above 20,000 Hz are inaudible to humans.

  • Hearing Variations: Some animals, such as dogs, can hear frequencies that humans cannot, particularly high-frequency sounds.

  • Applications of Sound: Ultrasound is utilized in various fields, especially in medical imaging.

Examples & Real-Life Applications

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Examples

  • Dogs responding to high-frequency whistles that their owners cannot hear.

  • Ultrasound machines used in hospitals to create images of internal organs.

Memory Aids

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🎵 Rhymes Time

  • If it's twenty and below, it's a low sound no-go; If it's twenty thousand high, it’s a sound we can't quantify.

📖 Fascinating Stories

  • Once upon a time, in a land of sounds, there lived dogs who could hear the highest sounds around. While humans could hear the whispers of the trees, dogs heard the calls of the wind with ease.

🧠 Other Memory Gems

  • A for Audible, I for Inaudible, U for Ultrasound – just remember A, I, U!

🎯 Super Acronyms

AUDIBLE

  • Animals Understand Detectable In Between Lower Extremes. It helps recall which frequencies we can hear.

Flash Cards

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Glossary of Terms

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  • Term: Audible Sound

    Definition:

    Sound frequencies detectable by the human ear, typically in the range of 20 Hz to 20,000 Hz.

  • Term: Inaudible Sound

    Definition:

    Sound frequencies that are below 20 Hz or above 20,000 Hz, which cannot be detected by the human ear.

  • Term: Frequency

    Definition:

    The number of vibrations or oscillations of a sound wave per second, measured in Hertz (Hz).

  • Term: Ultrasound

    Definition:

    Sound waves with frequencies above the human hearing range (greater than 20 kHz), used in medical diagnostics.

  • Term: Hertz (Hz)

    Definition:

    The unit of frequency, representing one cycle per second.