UTZ- Sound Spectrum & Waves

UTZ

Range of human hearing?

20 Hz–20 kHz

Sound below 20 Hz?

Infrasound

Sound above 20 kHz?

Ultrasound

Example of infrasound source?

Earthquake

Example of ultrasound user in animals?

Bat

Low frequency → detail or distance?

Distance

High frequency → detail or distance?

Detail

Example of low frequency sound?

Drum

Example of high frequency sound?

Bird chirp

Human ear detects which spectrum part?

Audible sound

Type of sound wave?

Longitudinal

Medium needed by sound?

Air (or matter)

v = f × ?

λ (wavelength)

Frequency ↑ → wavelength?

Decreases

Frequency ↑ → pitch?

Increases

Speed of sound in air?

343 m/s

Speed of sound in water?

1500 m/s

Speed of sound in steel?

5900 m/s

Why sound faster in steel?

Elasticity

Sound energy relation with frequency?

Directly proportional

Crystal used in ultrasound?

Quartz (PZT)

Effect converting electricity ↔ sound?

Piezoelectric

Without piezoelectric effect, no?

Ultrasound

Formula: v = √( ? ÷ ? )

Elasticity ÷ Density

Factor affecting velocity?

Medium

Faster in muscle or fat?

Muscle

Velocity symbol?

v

Unit of frequency?

Hertz

1 MHz = ? Hz

1,000,000 Hz

Frequency symbol?

f

Low frequency ultrasound range?

2–5 MHz

High frequency ultrasound range?

7–15 MHz

What is wavelength?

Distance between two compressions in a wave.

Short wavelength effect?

Higher detail, less penetration.

Long wavelength effect?

Lower detail, deeper penetration.

is Soundwave Mechanical or electromagnetic?

Mechanical

is Soundwave Needs medium: yes or no?

yes

Difference between sound and light waves?

Sound is mechanical & needs a medium; light is electromagnetic & can travel in vacuum.

What is attenuation?

Reduction in sound wave strength as it travels

What are the three causes of attenuation?

Absorption, reflection, scattering.

Which frequency attenuates more, high or low?

High frequency.

Why do abdominal scans use low frequencies?

To penetrate deeper tissues.

Formula: Z(acoustic impedance) = ? × ?

Density × Velocity

What does acoustic impedance determine?

How much sound is reflected or transmitted at a boundary.

What is acoustic mismatch?

Large impedance difference between two media.

Example of mismatch?

Air vs tissue

Why is ultrasound gel used?

To eliminate air and reduce mismatch.

Intensity formula = Power ÷ ?

Area

Unit of intensity measurement in sound?

Decibel (dB)

Why is intensity control important in ultrasound?

To prevent tissue heating or damage.

High frequency in ultrasound gives what advantage?

Greater detail (resolution).

Low frequency in ultrasound gives what advantage?

Deeper penetration.

Example where sound travels slower despite higher density?

Fat (slower than muscle).

Does higher density always mean faster sound?

No — elasticity also matters.

Which two factors affect sound speed in a medium?

Density and elasticity.

Why is piezoelectricity important in ultrasound?

It enables both sound generation and echo detection.

What do crystals do when echoes return?

Convert vibrations back into electricity.

What is the piezoelectric effect?

Crystals vibrate when electricity is applied, generating sound waves.

Analogy for sound speed in different media?

Passing a message in a line of kids — tightly packed kids = faster message.

Why does sound travel faster in steel than air?

Steel is denser and more elastic.