Sound Waves & Hearing

What type of wave is sound in air?

A longitudinal mechanical wave.

How is sound produced?

By a vibrating object.

How does sound travel through air?

By compressions and rarefactions as air particles vibrate.

Why can sound not travel through a vacuum?

There are no particles to transfer the vibrations.

Can sound travel through solids?

Yes, by causing particles in the solid to vibrate.

Can sound travel through liquids?

Yes, through vibrations of particles in the liquid.

What is the approximate speed of sound in air?

330 m/s.

Why does sound travel at different speeds in different materials?

The properties and interactions of particles differ between materials.

What happens when sound enters a different medium?

Its speed and wavelength may change, but its frequency remains constant.

What determines the pitch of a sound?

Its frequency.

What determines the loudness of a sound?

Mainly the amplitude of the sound wave.

What is the normal human hearing range?

Approximately 20 Hz to 20,000 Hz (20 kHz).

What is infrasound?

Sound with a frequency below 20 Hz.

What is ultrasound?

Sound with a frequency above 20,000 Hz.

What happens when sound waves reach the ear?

They cause the eardrum and other structures to vibrate, producing the sensation of sound.

Why can humans only hear a limited range of frequencies?

The ear's structures can respond effectively only within a limited frequency range.

How can vibrations in a solid produce sound waves?

A vibrating solid causes surrounding particles to vibrate, transferring sound energy.

How can sound waves produce vibrations in a solid?

Sound transfers energy to the solid, causing it to vibrate.

What is an echo?

A reflected sound wave heard after the original sound.

How can the speed of sound in air be measured using echoes?

Measure the distance to a reflecting surface and the time for the echo to return, accounting for the return journey.

Why must the return journey be considered in an echo experiment?

Sound travels to the reflecting surface and back.

How can two microphones measure the speed of sound?

Measure their separation and the time delay between the sound reaching them.

Why is an electronic timer useful when measuring sound speed?

Sound travels quickly, so short time intervals need accurate measurement.