The unit used for measuring the intensity of sound is decibel. The faintest sound that the human ear can detect is assigned a value of 0 decibels. Study this table and answer the question. Study this table and answer the question. Which of these could be the decibel level during a severe thunderstorm?
Decibel
Example
Maximum safe exposure
0
the quietest sound that you can hear
(Safe)
30
whisper, quiet library
(Safe)
60
normal conversation, sewing machine, typewriter
(Safe)
90
tools in a workshop, truck traffic
8 hours per day
100
Chainsaw, pneumatic drill
2 hours per day
115
sandblasting, loud rock concert, auto horn
15 minutes per day
140
loud gunshot, jet engine: noise causes pain and may injure unprotected ears
Maximum allowed noise with a hearing protector
Important Questions on Sound
The unit used for measuring the intensity of sound is decibel. The faintest sound that the human ear can detect is assigned a value of 0 decibels. Study this table and answer the question. Psychologists believe that if one sound source has10 times the power of another sound source, we hear the first about twice as loud - thus its decibel value will be double. If the decibel value of the sound from a 50W source is 60 dB, what would be the approximate decibel value of the sound from a loud 2500W source?
| Decibel | Example | Maximum safe exposure |
| 0 | the quietest sound that you can hear | (Safe) |
| 30 | whisper, quiet library | (Safe) |
| 60 | normal conversation, sewing machine, typewriter | (Safe) |
| 90 | tools in a workshop, truck traffic | 8 hours per day |
| 100 | Chainsaw, pneumatic drill | 2 hours per day |
| 115 | sandblasting, loud rock concert, auto horn | 15 minutes per day |
| 140 | loud gunshot, jet engine: noise causes pain and may injure unprotected ears | Maximum allowed noise with a hearing protector |
Pooja and her friends collected the information about the audible range for different animals. Which of these animals could communicate with each other at a frequency greater than so that they are not heard by their predators?
