Sounds that are pleasant to hear are called ultrasounds.

The device that transmits ultrasounds in SONAR is called a/an _______.

• The receiver receives the sounds reflected from underwater objects.

Echo is the_________ of sound.

• Refraction is the bending of waves when they enter one medium from another medium.

Sound cannot travel through _________.

The multiple reflection of sound by a closed surface is called _______

• Amplified sound is any sound which is made louder.
• Echo is the reflection of sound after a delay.

If a sound is amplified, it will be comparatively ______.

Echo is the reflection of a sound.

Sound cannot travel in space because sound cannot travel through _______.

154Hz sound frequency comes under ________ .

• Sounds with frequencies less than 20Hz are called infrasound.
• Sounds with frequencies more than 20kHz are called ultrasounds.

Infrasound have more ____________.

ECG uses _________ for the medication.

Human cannot listen to _________.

Kidney stones can be cured using ________.

• High energy sound waves are passed through the body without injuring it and break the stone into small pieces.
• This technique is known as lithotripsy.

Giraffe uses ______ sounds for communication.

Which of the following parts of the ear transmits the electrical signals to the brain for interpretation?

• The optic nerves relay messages from your eyes to your brain to create visual images.
• Cochlea is the part of inner ear.
• Blood vessels deliver blood to the organs and tissues in your body.

Increase in wavelength ___________ frequency.

• Wave speed= frequency × wavelength.
• Frequency = wave speed/wavelength.

The frequency of vibration of an object is 25000 Hz. A person ____ hear it.

Frequency above 20KHz is called ultrasound.