The frequency range in which some common animals can hear is shown in the graphic below. A manufacturer wants to create a pest controller that will emit loud sounds that can be heard by insects and rodents (and will hence drive them away), but will not affect humans and pets. What frequencies of sound should the pest controller produce?
Important Questions on Sound
An astronaut is moving in space when a big explosion occurs about a hundred meters behind him. How will the astronaut come to know about the explosion?
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 |
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 |
