2. When I ask you to describe what
sound is, what comes to mind:
A dog barking?
A television with the volume turned up?
Music playing inside a car?
The hum of traffic outside it?
Ponder this…
3. The magic of sound
By the end of this presentation you should
be able to answer the following:
● What is sound?
● What are the types of sound?
● How can ultrasound be used to help us
in everyday life?
● Why are there different ways to
measure with ultrasonic devices?
4. What is sound?
Sounds is the movement of energy in
vibrations that travel through the air/water
as sound waves.
When the vibrations move through air they
disturb it causing it to expand and contract.
Sound also can bounce off objects,
changing the direction and strength of the
vibrations.
5. The wavelength represents variation in air pressure and is the distance over
which the wave’s shape repeats.
An oscillation of a wave is defined how long it takes for a wave to move from
starting position, one position to the next and back to the start.
Amplitude refers to the intensity or power of the sound wave, and relates to
volume.
The frequency of a wave is defined as number of oscillations the wave
completes in a certain amount of time (usually seconds).
The unit of measurement for sound is a hertz (Hz), and it is based on how
many oscillations occur per second.
Vocabulary
9. When sound travels
● As sound travels it can be reflected, refracted, or focused.
● Reflection and refraction occur when the waves interact
with a medium of differing properties. Focused sound may
use a piece of technology to direct it.
● Sound travels at slower speeds in gases than liquids; it
travels the fastest in solids.
○ Sound travels at 343 m/s in air; it travels at 1,484 m/s in
water; and at 5,120 m/s in iron.
10. Producing ultrasound waves
Depending on the
direction, the transducers
may be positioned at an
angle rather than
perpendicular to the object
being tested.
One way to replicate ultrasound wave frequencies is with a
transducer.
11. Uses of Ultrasonics
There are so many uses in the real world using
ultrasonic devices. Many of these applications
require that sound travel through a medium other
than air. Examples include:
● Diagnostic and medical imaging
● Communication and echolocation; SONAR
● Engineering Design
12. Measuring distance with sound
In air, sound travels at a constant speed, which means we can measure distance
by seeing how long it takes for a sound to hit and object and bounce back to the
sensor.
Ultrasonic waves can be used to accurately measure
distances with special sensors.
Sender
Receiver
14cm
Reflected wave
Original wave
13. With the use of sensors like the ones above and the use of computer programming, many
opportunities are available for humans to accurately measure distance at a faster more
reliable pace than our use of a ruler or tape measure.
Why use a sensor
14. Let’s go back to those questions...
Turn and talk to your partner.
● What is sound?
● What are the types of sound?
● How can ultrasound be used to help us in our lives?
● Why are there different ways to measure with
ultrasonic devices?
Extension: How might we use ultrasonic sensors that
measure distance to our advantage in our lives?
Editor's Notes
Image Source/Rights: Photo by Nextvoyage from Pexels, 2016, CC0 https://www.pexels.com/photo/amazing-bay-bridge-california-cars-675648/
Give students the target outcomes for the lesson. Make sure they have time throughout the lesson slides to pause and discuss with their precision partner.
The frequency of a wave is defined as number of cycles this wave completes in a unit of time. This unit of time is typically taken to be a second. Frequency of 1Hz, or one Hertz, indicates that the wave oscillates one cycle over a time period of 1 second.
Begin by referring back to the vocabulary from the previous page. Identify oscillation, frequency, and tell students the oscillations could be measured in hertz.
Also, point out that wavelength is the distance between two points at the same position (crest, trough, starting position). I would wait on explaining amplitude.
Image Source/Rights: Sabina Schill, 2018, University of Colorado at Boulder
Sound waves are everywhere around us even when we cannot hear them. Sound can travel at frequencies above or below what our ears can register. Some animals can hear sounds with frequencies below what humans can register. Some sounds have too high of a frequency for us to hear.
Image Source/Rights: 2012 Irina Igel, Polytechnic Institute of NYU, https://www.teachengineering.org/activities/view/nyu_soundwaves_activity1
Sound frequencies below and above human threshold have been used to support engineering and medical fields. Ultrasounds can be used to take images of soft tissues and it does not risk exposure to radiation, like an x-ray would. The use of ultrasonic waves is also incorporated into navigation and detection of items in water (SONAR).
Source: http://en.wikipedia.org/wiki/Sonography
https://en.wikipedia.org/wiki/Medical_ultrasound
https://en.wikipedia.org/wiki/Sonar
Image Source/Rights:
2017 FDA, https://www.fda.gov/radiation-emittingproducts/radiationemittingproductsandprocedures/medicalimaging/medicalx-rays/ucm115340.htm
2017 NOAA, https://sanctuaries.noaa.gov/missions/2009tortugas/mapping.html
2006 Moroder, CC BY-SA 3.0 https://commons.wikimedia.org/wiki/File:CRL_Crown_rump_lengh_12_weeks_ecografia_Dr._Wolfgang_Moroder.jpg
2012 Irina Igel, Polytechnic Institute of NYU, https://www.teachengineering.org/activities/view/nyu_soundwaves_activity1
The image is showing a pulse-echo transducer with an angle beam rather than direct beam because of the location and direction of transducer B.
Image Source/Rights: 2017 Kendra Randolph, Michigan State University
Image
Image source: 2012 Irina Igel, AMPS GK-12 Program, Polytechnic Institute of New York University.
image source: https://www.sunfounder.com/ultrasonic-module-hc-sr04-distance-sensor.html
This is the actual sensor used in the activity with the Arduino microcontroller. On the previous slide it was labeled sender and receiver. These relate to our trigger and echo pins on the sensors themselves.
Have students work with their partner to discuss the 4 questions. It would be up to the discretion of the teacher to decide how students would present their ideas. I would consider some sort of graphic or visual. Make sure to stress to students though “Being able to answer these questions is your ticket to joining another group to work on your application and design of your own ultrasonic sensors.”