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How Headphones Cancel the Hum of a Plane

6th grade nonfiction passage about sound waves and noise: 225 words, six questions, an answer key and vocabulary.

6th grade nonfiction sound waves and noise 225 words

How Headphones Cancel the Hum of a Plane

On a long flight, the engines make a steady roar that tires your ears. Some headphones can make that roar fade without playing any music at all. They do it with a clever trick that uses the nature of sound.

Sound travels as a wave. You can picture a wave as a row of hills and valleys, where the air is squeezed together and then spread thin. Now imagine two waves meeting. If a hill from one wave lines up with a valley from the other, they cancel each other out, and the air barely moves at all.

Noise-canceling headphones use this idea. A tiny microphone on the outside listens to the sound around you. A small computer chip then makes a new wave that is the mirror image of the incoming one, with its hills where the noise has valleys. The speaker plays that mirror wave into your ear, and the two sounds nearly erase each other.

The trick works best on steady, low sounds like an engine drone, because they are easy to predict. It works less well on sudden noises, such as a dropped tray or a person talking, because the chip cannot match them quickly enough. That is why you can still hear a flight attendant over the hum. Thick padding around the ear helps block some of the rest.

Questions

  1. What do the hills and valleys of a sound wave stand for? in the text

  2. What does the tiny microphone on the outside of the headphones do? in the text

  3. What kind of wave does the computer chip make? in the text

  4. Which kinds of sounds do these headphones handle best? in the text

  5. Why can a person still hear a flight attendant talking while wearing them? think about it

  6. What would happen if the hills of the second wave lined up with the hills of the noise instead? think about it

Words to know

wave
a pattern of up and down movement that carries energy
valley
the low part of a wave
cancel
to remove or wipe out the effect of something
microphone
a device that picks up sound
drone
a low sound that keeps going and going
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One passage, three levels

The same topic and facts written three ways, so a mixed class can read and talk about one text. Each group’s sheet shows only a shape; the key says which is which.

● Easier · 201 words · Flesch-Kincaid grade 2.1

On a long flight, the engines roar all the time. It can tire your ears. Some headphones can make the roar fade. They do not even need to play music. They use a clever trick with sound.

Sound travels as a wave. A wave has hills and valleys. In the hills, air is squeezed together. In the valleys, air is spread thin. Now picture two waves that meet. A hill from one wave lines up with a valley from the other. They cancel each other out. The air hardly moves at all.

Noise-canceling headphones use this idea. A tiny microphone outside listens to the sound around you. A small chip makes a new wave. It is a mirror image of the noise, with hills where the noise has valleys. The speaker plays this wave into your ear. The two sounds nearly erase each other.

This works best on steady, low sounds, like an engine drone. They are easy to predict. It works less well on sudden sounds, like a dropped tray or a person talking. The chip cannot match them fast enough. So you can still hear a flight attendant. Thick padding around the ear blocks some of the rest.

▲ This passage · 225 words · Flesch-Kincaid grade 5.4

On a long flight, the engines make a steady roar that tires your ears. Some headphones can make that roar fade without playing any music at all. They do it with a clever trick that uses the nature of sound.

Sound travels as a wave. You can picture a wave as a row of hills and valleys, where the air is squeezed together and then spread thin. Now imagine two waves meeting. If a hill from one wave lines up with a valley from the other, they cancel each other out, and the air barely moves at all.

Noise-canceling headphones use this idea. A tiny microphone on the outside listens to the sound around you. A small computer chip then makes a new wave that is the mirror image of the incoming one, with its hills where the noise has valleys. The speaker plays that mirror wave into your ear, and the two sounds nearly erase each other.

The trick works best on steady, low sounds like an engine drone, because they are easy to predict. It works less well on sudden noises, such as a dropped tray or a person talking, because the chip cannot match them quickly enough. That is why you can still hear a flight attendant over the hum. Thick padding around the ear helps block some of the rest.

■ Harder · 256 words · Flesch-Kincaid grade 7.1

On a long flight, the engines produce a steady roar that gradually wears out your ears. Some headphones can make that roar fade into the background without playing any music at all. They accomplish this with a clever trick that takes advantage of the basic nature of sound.

Sound travels through the air as a wave. You can picture a wave as a row of hills and valleys, where the air is alternately squeezed together and then spread thin. Now imagine two waves meeting each other. If a hill from one wave lines up exactly with a valley from the other, they cancel each other out, and the air barely moves at all.

Noise-canceling headphones put this idea to work. A tiny microphone on the outside of the ear cup continually listens to the sound around you. A small computer chip then builds a new wave that is the mirror image of the incoming one, with its hills positioned where the noise has valleys. The speaker plays that mirror wave into your ear, and the two sounds nearly erase each other.

The technique works best on steady, low sounds such as an engine drone, because they are easy for the chip to predict. It works far less well on sudden noises, like a dropped tray or a person talking, because the chip cannot match them quickly enough. That is why you can still hear a flight attendant speaking over the hum. Thick padding around the ear also helps to block some of the remaining sound.

Download as one PDF

How to use it

  1. Press Read it big (or B) to put the text on the projector, or Full screen (F) to fill the whole screen.
  2. Ask the questions one at a time and use Show answer when the class has decided. A shows or hides every answer.
  3. Print student copy for the class, or Print with answers for yourself.

Ideas for class

  • Before reading, put wave, valley, cancel, microphone and drone on the board with their meanings from the Words to know section and have students predict what the text will be about.
  • Read it aloud once while students follow along, then have them reread it alone or with a partner. At a calm 100 words a minute it takes about 2 minutes to read aloud.
  • Use the Read it big button (or B) to put the text on the projector, and Show answer on one question at a time so the class commits to an answer first.
  • Question 5 asks the reader to infer. Ask students to point to the words in the passage that led them to their answer.
  • Ask students to write one question the passage did not answer, then look for the answer in a book or on a classroom screen.
  • Print the student copy for independent work and keep the answer-key copy for yourself.

Related

Questions

What reading level is "How Headphones Cancel the Hum of a Plane"?

It was written for 6th grade. It has 225 words and works out to a Flesch-Kincaid grade level of about 5.4. That is a formula's estimate from sentence length and syllables, and it is not a Lexile or a guided reading level, so check it against your students.

What do the questions ask?

There are six. 4 ask for something the text says directly and 2 ask the reader to work something out from clues. Each has an answer in the key, and the answers are written as a teacher would accept them, not as the only possible wording.

How long does it take to read?

About 2 minutes read aloud at 100 words a minute. For a one-minute fluency check, paste it into the fluency timer and use the word count.

Can I print it?

Yes. Print student copy gives the passage, the questions with lines to write on, and the word meanings. Print with answers gives the same page with the answers filled in. Both are made in your browser.

Is this passage from a published book?

No. It was written for Peabody Teach, so there is no book to buy and no login to read it.

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