The Hum Below Hearing: teacher key

Ghosts, grade 9 edition, written for 9th grade. Sound too low to hear well, a faulty fan in a lab and a 2003 concert show how scientists test spooky feelings. The evidence runs from infrasound to the Society's Census and the brain's waking hours.

Read the book. Print this page for the key.

Questions and answers

1. What is infrasound?
   • Sound with a pitch below 20 hertz (answer)
   • Sound above 20,000 hertz
   • Sound made only by machines
2. What did Vic Tandy trace eerie feelings in a lab to?
   • A cold pipe
   • A rumbling floor
   • A faulty extractor fan that made very low sound (answer)
3. Why would a room with infrasound not affect everyone the same way?
   • It would always affect everyone
   • Only a minority of people are sensitive to its effects (answer)
   • Infrasound can only be heard by children
4. At Hampton Court, who reported more unusual experiences?
   • People who already believed in ghosts (answer)
   • People who walked alone
   • People who arrived late
5. What did the SPR's Census of Hallucinations do?
   • It tested rooms for sound
   • It asked thousands of people about unexplained experiences (answer)
   • It measured the weather
6. What does inaudible mean?
   • Too bright
   • Too far away
   • Cannot be heard (answer)

Words

• infrasound: very low sound
• inaudible: cannot be heard
• census: big count
• pareidolia: seeing faces
• paralysis: cannot move