Chapter 18

Can sound travel through deep space? Explain.

Can sound travel through deep space? Explain.

Sound cannot travel in space because there is no physical medium for the wave to travel through.

What will happen to the speed of a sound wave as it passes from air into water? Explain.

The speed of the wave will increase because sound travels faster in a liquid than in a gas.

What will happen to the speed of sound as air temperatures drop from 30 °C to 20 °C? Explain.

The speed will decrease as the temperature drops because sound travels slower as air molecules move slower.

If the wavelength of a sound wave gets longer, what happens to the sound’s pitch?

The pitch gets lower.

How will the characteristics of a sound change if the amplitude of its wave increases?

The sound’s loudness and intensity will increase.

You and a friend hear a sonic boom, which your friend describes as an “intense” sound. What is wrong with your friend’s description?

Your friend is describing the loudness of the sound, which is subjective. Intensity is a measure of the power in a sound wave.

A person raises his voice from 60 dB to 80 dB. How much more sound wave power is he projecting?

one hundred times more

A French horn and a trumpet can play notes of the same pitch and frequency but sound very different. Why is that so?

The French horn and trumpet each have a different timbre, the result of their different design, materials, and manner of being played.

Which anatomical structure together acts as a resonating chamber for the human voice?

the throat and sinuses

tympanic membrane

(ear drum)

diaphragm

diaphragm

larynx

larynx

auditory canal

auditory canal

vocal cords

vocal cords

cochlea

cochlea

Trace the path of a sound wave from entering the human ear to its conversion into a nerve impulse.

Sound enters the outer ear and travels through the auditory canal to the tympanic membrane. The membrane converts the sound energy to kinetic energy. The bones of the middle ear transfer the kinetic energy to the fluid in the inner ear. In the inner ear, the energy is converted to nerve impulses by hair cells in the cochlea.

Which human muscle is particularly vital for producing sound? Explain.

The diaphragm is vital for producing sound. It forces air from the lungs over the vocal cords and controls the volume of air that does so.

What determines whether a sound is considered infrasonic?

Sound is considered infrasonic if its frequency is lower than the range of human hearing.

What advantages does infrasonic sound communication have for elephants?

Infrasonic sound can be detected over large distances and passes easily through vegetation.

Why is sonography a desirable means for diagnosing disease?

It does not require expensive and risky surgery.

Is ultrasound used only for medical purposes? Explain.

No. Ultrasound also has nonmedical applications, such as examining welds for defects.

Small stereo systems with built-in speakers typically do not produce bass tones well. Why is this?

The small built-in speakers found in such systems are not well suited to creating the lowfrequency vibrations of bass tones.

What characteristic of ultrasonic sound makes it particularly suited to locating underwater objects?

The ultrasonic sound waves emitted by sonar reflect strongly from the boundaries between different types of media, such as the boundary between seawater and the ocean floor.