The Great Expedition Series, Book 14

A Million Whys: The Sound Expedition for Curious Kids

By Crafty Clover. Published by Million Whys Press.

Why Does Every Sound Begin with Something Shaking? Why Does a Megaphone Make Your Voice Carry Farther? Why Can You Hear a Clear Echo in a Canyon but Not in a Forest? This book answers 150 questions like these, one question per page, each with a short video answer. Six expeditions: Vibrations & Waves, Loud, Soft, High & Low, Sound Makers & Machines, How Sound Travels, Echoes & Sonar Clues, and Hearing & Listening Safely.

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All 150 questions

Tap a question to watch its video and read the answer.

Expedition 1: Vibrations & Waves

1. Why Does Every Sound Begin with Something Shaking?
2. Why Does Your Throat Tickle When You Hum?
3. Why Does a Ruler Buzz When You Flick It Off the Edge of a Desk?
4. What Is a Sound Wave Actually Made Of?
5. Why Does a Slinky Show How a Sound Wave Moves?
6. How Are Water Ripples Like Sound Waves?
7. Why Does Rice Dance on Plastic Wrap When You Bang a Pot Nearby?
8. Why Does a Tuning Fork Keep Ringing for a While?
9. Why Can You Feel Deep Bass Thumping in Your Chest?
10. Why Does Pushing a Swing at Just the Right Moment Work So Well?
11. Why Does a Tuning Fork Sound Louder When You Touch It to a Table?
12. Why Can a Tin-Can Phone Carry a Voice?
13. What Does It Mean When We Say a Sound Has a Frequency?
14. Why Do Puddles Shiver When a Heavy Truck Rumbles By?
15. Why Do Wood, Metal, and Glass Sound Different When You Tap Them?
16. Why Does a Bottle Hum When You Blow Across the Top?
17. Why Does a Fan Hum Higher When It Speeds Up?
18. Why Does a Card in Bicycle Spokes Make a Buzzing Motor Sound?
19. Why Do Refrigerators Hum?
20. Why Can You Hear a Mosquito's Wings but Not a Slowly Flapping Bird's?
21. Why Do Sound Waves Push and Squeeze Instead of Going Up and Down?
22. Why Does a Stadium Wave Move Across the Crowd While the People Stay Put?
23. Why Do Two Nearly Matching Sounds Make a Wobbling Wah-Wah?
24. Why Can't We See Sound Waves?
25. Why Does a Fast-Shaking Object Look Blurry?

Expedition 2: Loud, Soft, High & Low

26. Why Are Big Things Usually Lower in Sound than Small Things?
27. What Makes One Sound Louder than Another?
28. What Makes a Sound High or Low?
29. Why Do Mosquitoes Whine High While Bumblebees Buzz Low?
30. Why Does a Ruler Twang Lower When More of It Hangs Over the Edge?
31. Why Does the Sound of Pouring Water Get Higher as the Glass Fills?
32. What Do Decibels Measure?
33. Why Do 10 More Decibels Sound About Twice as Loud?
34. Why Does Cupping Your Hands Behind Your Ears Help You Hear?
35. Why Does Fresh Snow Make Everything Sound So Quiet?
36. Why Do Carpets and Curtains Make a Room Sound Quieter?
37. Why Do Deep Rumbles Carry Farther than Squeaks?
38. Why Can't We Hear a Dog Whistle?
39. Why Would the Quietest Room in the World Feel Strange?
40. Why Is It Hard to Hear a Friend in a Noisy Room?
41. Why Do People Talk Louder When It Is Noisy?
42. How Can Two Sounds Cancel Each Other Out?
43. Why Do Foghorns Make Deep Sounds?
44. Why Do Longer Wind-Chime Tubes Ring Lower?
45. Why Can You Hear the Ocean in a Seashell?
46. Why Does a Sound Seem Softer When You Are Farther Away?
47. Why Do You Hold Your Breath When You Try to Hear a Tiny Sound?
48. Why Do Phone Calls Make Voices Sound Thinner?
49. Why Do Sounds Seem Muffled Through a Wall?
50. How Can You Hear Someone Talking From Around a Corner?

Expedition 3: Sound Makers & Machines

51. Why Does a Megaphone Make Your Voice Carry Farther?
52. Why Do Small Speakers Sound Thin and Big Speakers Sound Full?
53. Why Does a Microphone Squeal When It Gets Close to a Speaker?
54. Why Does a Bell Keep Ringing After You Hit It?
55. Why Do Sirens Rise and Fall in Pitch?
56. Why Does a Phone Buzz in Vibrate Mode?
57. Why Are Vacuum Cleaners and Hair Dryers So Noisy?
58. Why Do Some Quiet Electric Cars Hum on Purpose?
59. How Can a Needle in a Groove Play a Song?
60. Why Does Snapping Your Fingers Make a Snap?
61. Why Does a Clap Make a Sharp Crack?
62. Why Does Bubble Wrap Crack When You Squeeze It?
63. Why Does Velcro Make a Ripping Sound?
64. Why Does a Soda Can Go Psst When You Open It?
65. Why Do Ice Cubes Crackle in a Drink?
66. Why Does Rain Sound Louder on a Metal Roof than on Grass?
67. Why Do Squeaky Doors and Sneakers Squeak?
68. Why Does Wind Howl Around a House?
69. Why Do Footsteps Sound Different on Different Floors?
70. Why Does a Balloon Squeal When You Let the Air Out?
71. Why Does a Spoon Hung on a String Sound Like a Big Bell?
72. Why Does a Phone Sound Louder in a Bowl?
73. Why Does Crunchy Food Sound So Loud When You Chew It?
74. Why Do Cars Need Mufflers?
75. Why Does a Jar Lid Pop When You Open It?

Expedition 4: How Sound Travels

76. Why Can't Sound Travel Through Empty Space?
77. Why Does Sound Travel Faster in Water than in Air?
78. Why Does Sound Travel Fastest Through Solid Metal?
79. Why Does a Siren Sound Higher as It Comes Toward You and Lower as It Goes Away?
80. Why Can You Hear a Train Through the Rails Before You Hear It in the Air?
81. Why Does a Whip Crack?
82. Why Does a Jet Flying Faster than Sound Make a Boom?
83. Why Does Sound Carry Farther on a Cold, Still Morning?
84. Why Do Voices Carry So Far Across a Calm Lake?
85. Why Do Voices Sound So Strange Underwater?
86. Why Is It Hard to Tell Where a Sound Is Coming From Underwater?
87. Why Does Bass Travel Through Walls When High Sounds Don't?
88. Why Is Sound a Little Faster on a Hot Day?
89. How Fast Does Sound Travel?
90. Why Can a Long Tube Carry a Whisper?
91. Why Can Astronauts Talk to Each Other on a Spacewalk?
92. Why Do Scuba Divers Use Hand Signals Instead of Talking?
93. Why Do Highways Have Tall Walls Beside Them?
94. Why Can a Whisper Travel Along a Curved Wall?
95. Why Does a Plane Seem to Be in a Different Place than Its Sound?
96. Why Does a Crowd of People Sound Like a Steady Roar?
97. Why Do Voices Sound Thin High Up on a Mountain?
98. Why Does Snow Squeak When It Is Very Cold?
99. Why Does a Frozen Lake Sometimes Make Strange Pew-Pew Sounds?
100. Why Do Some Beaches Have Singing Sand?

Expedition 5: Echoes & Sonar Clues

101. Why Can You Hear a Clear Echo in a Canyon but Not in a Forest?
102. Why Does Your Voice Sound Bigger in a Bathroom?
103. Why Does a Shout in a Tunnel Keep Ringing?
104. How Can You Use an Echo to Measure Distance?
105. Why Do Car Parking Sensors Beep Faster as the Car Gets Closer?
106. How Can Some People Use Clicking Sounds to Sense Walls and Doorways?
107. What Is Ultrasound, and How Do Bats and Doctors Use It?
108. Why Can a Shout Take Seconds to Bounce Back From a Far-Away Mountain?
109. Why Do Recording Studios Have Foam Wedges on the Walls?
110. Why Can't You Hear an Echo in a Small Room?
111. Why Does Clapping Between Two Flat Walls Make a Zinging Sound?
112. Why Can Tapping a Wall Tell You Where the Hidden Beams Are?
113. Why Do People Tap Things to Check If They Are Cracked or Hollow?
114. How Do Plumbers Find a Leak in a Pipe Using Sound?
115. How Can Scientists Use Sound to Measure How Thick Ice Is?
116. Why Can You Tell How Big a Room Is with Your Eyes Closed?
117. Why Do You Sometimes Hear Your Own Voice Echo on a Phone Call?
118. Why Did Sailors Blow a Horn Near Cliffs and Listen for the Echo?
119. Why Does Your Voice Sound Hollow Inside a Bucket or a Big Pipe?
120. How Can Sound Waves Clean Eyeglasses?
121. Can a Singer Really Break a Glass with Their Voice?
122. Why Can Sound Hold Tiny Bits of Foam in Mid-Air?
123. Why Does Sand Make Patterns on a Vibrating Plate?
124. Why Do Some Backing-Up Trucks Go Shh-Shh Instead of Beep-Beep?
125. Why Can Echoes Make a Speech Hard to Understand?

Expedition 6: Hearing & Listening Safely

126. What Do the Tiny Hair Cells in Your Ears Do, and Why Can't They Grow Back?
127. Why Do People Who Work Near Loud Machines Wear Ear Protection?
128. Why Do Ear Defenders Matter at Fireworks, Motor Races, and Loud Concerts?
129. How Can You Tell If Your Headphones Are Too Loud?
130. Why Do Listening Breaks Help Your Ears?
131. Why Do Your Ears Sometimes Ring After a Very Loud Noise?
132. Why Do Hearing Tests Use Beeps in Headphones?
133. How Does a Hearing Aid Work?
134. Why Do Captions on Videos Help Lots of People?
135. Why Do Ears Make Earwax?
136. Why Shouldn't You Poke Anything Into Your Ears?
137. Why Are Our Outer Ears Shaped Like Curly Funnels?
138. Why Do Some Crosswalks Beep or Chirp?
139. Why Do Some Alarms Flash a Light as Well as Make a Sound?
140. Why Does Background Noise Make It Harder to Focus?
141. Why Is It Risky to Wear Headphones While Biking or Crossing the Street?
142. Why Can Younger People Hear Some Sounds That Adults Can't?
143. How Can You Make a Noisy Room Quieter?
144. What Is White Noise, and Why Does It Hide Other Sounds?
145. How Do Vibrating Alarm Clocks and Flashing Doorbells Help People Who Are Deaf or Hard of Hearing?
146. How Can People Who Are Deaf or Hard of Hearing Enjoy Music?
147. Why Should You Tell a Grown-Up If Your Ears Hurt or Sounds Seem Muffled?
148. Why Do Some Toys and Kids' Headphones Have a Volume Limit?
149. Why Do Some Animals Have Giant Ears?
150. What Is the Faintest Sound a Person Can Hear?