Question

Which of the following sound frequencies can be heard by a woman having a normal hearing range ? *

25,000 Hz

15 Hz

40,000 Hz

8000 Hz

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Answer 1

↬ (8000 Hz) as it is a Audible sound.

You have learnt that a vibrating object preduces sound. But, when you vibrate your hand forward and backward, you do not hear any sound.

Why it is so ?

• The reason of this is that frequencyless than 20 Hz. Also frequency higher than 20,000 Hz cannot be heard by Humans.

The sound whose frequency lies between 20 Hz and 20,000 Hz which we are able to hear is called audible sound. So, the audible range of human ears is 20 Hz - 20,000 Hz.

The sounds (inaudible for humans) having frequency less than 20 Hz are known as infrasonic sounds.

• Rhinoceros communicates with one another by using infrasonic sounds of the frequency as low as 5 Hz.
• The animals like Whales and elephants also preduces infrasonic sounds.
• A low frequency infrasonic soundsare preduced before the main shorkwaves during an earthquake. This sound when heard by animals make them alert and they show abnormal behaviour.

The sound (inaudible for humans) having frequency more than 20,000 Hz are known as ultrasonic sounds. You can't hear untrasonic sounds too.

• Animal like dolphin, bats and porpoises preduces untrasonic sounds. Bats use it to locate objects and dolphin use it to find their way in ocean.

Dogs can hear 40,000 Hz. There Special whistles knows as Galton 's whistles that can preduces sound of frequency more than 20,000 Hz. The owner of dogs use this whistles to give signals to their dogs.

Interesting to Know :

• The sound between the infrasonic sound and unltsonic sound are knowns as sonic sound.