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Select the right word given in the table :
  
decreased
increased
  Cochlea
 Amplitude
auditory
noise pollution
larynx
infrasonic
energy
Shriller
FrequencyVoice box
  
1. Sound of frequency lower than 20 Hz is called the .
 
2.  is also called larynx.
 
3. If the thickness of a vibrating string is, it will reduce its pitch.