11.4 Range of Hearing

Description

Quick Overview

The section discusses the audible range of sound for humans and other animals, defining infrasound and ultrasound, and their significance.

Standard

The range of human hearing extends from about 20 Hz to 20 kHz, while some animals can hear frequencies outside this range. The section illustrates the concept of infrasound (below 20 Hz), which is used by some animals for communication, and ultrasound (above 20 kHz), which has various applications including medical imaging.

Detailed

Range of Hearing

Understanding the frequency range of sounds is essential for recognizing how different beings perceive the world around them.

The human ear can typically hear frequencies ranging from 20 Hz to 20,000 Hz (20 kHz). Frequencies lower than this are known as infrasound. For instance, some animals like elephants can communicate using infrasonic sounds around 5 Hz.

Infrasound allows these large animals to understand their environment and coordinate themselves over great distances, as lower frequencies travel farther. Understanding sounds in this frequency range can also inform human awareness of natural phenomena, as some animals detect infrasound preceding events like earthquakes.

Conversely, frequencies above 20 kHz fall into the category of ultrasound. Animals such as dolphins and bats utilize ultrasound to navigate and hunt. Furthermore, ultrasound has been harnessed in various fields, notably in medical imaging techniques like echocardiography and ultrasonography, aiding in diagnosis and detection within human bodies.

As humans age, sensitivity to higher frequencies decreases, a phenomenon often not recognized until it impacts communication. This section further stresses the importance of understanding the audible range and its implications in both nature and technology.

Key Concepts

  • Audible Range: Defined as the frequencies that humans can hear, spanning from 20 Hz to 20 kHz.

  • Infrasound: Sound below 20 Hz used in animal communication and natural event detection.

  • Ultrasound: Sound above 20 kHz, applied in medical imaging and various industrial uses.

  • Frequency: The number of sound wave cycles per second known in Hertz (Hz).

Memory Aids

🎵 Rhymes Time

  • From twenty hertz to twenty k,We hear sounds in a joyful sway.

📖 Fascinating Stories

  • Once, a young child asked an elephant how it communicated. The elephant explained its secret language of low sounds, invisible to human ears, allowing it to converse over great distances.

🧠 Other Memory Gems

  • Remember 'In-U-Sound' for Infrasound, Ultrasound, and Sound.

🎯 Super Acronyms

H.U.S. - Hear, Understood, Sound - a reminder of the ranges we can perceive.

Examples

  • The sound from a ringing bell can be measured in Hz to determine if it falls within the human audible range.

  • Dolphins use ultrasound for echolocation while hunting for food in the ocean.

Glossary of Terms

  • Term: Audible Range

    Definition:

    The range of frequencies that can be heard by the human ear, typically between 20 Hz and 20 kHz.

  • Term: Infrasound

    Definition:

    Sound waves with frequencies below the audible range of human hearing (below 20 Hz).

  • Term: Ultrasound

    Definition:

    Sound waves with frequencies above the audible range of human hearing (above 20 kHz).

  • Term: Frequency

    Definition:

    The number of cycles of a wave that occur in a given time period, measured in Hertz (Hz).

  • Term: Echocardiography

    Definition:

    A medical imaging technique that uses ultrasound to create images of the heart.