Chapter 6 Book Interaction between Sound and Media Notes

What does attenuation mean in the context of sound waves?

Attenuation means the sound wave gets weaker as it travels through the body.

How is attenuation measured?

Attenuation is measured in decibels (dB).

+3 dB corresponds to what change in sound strength?

It means the sound is twice as strong.

What is the relationship between –3 dB and sound strength?

–3 dB means the sound is half as strong.

What causes sound attenuation?

Sound attenuation is caused by absorption, scattering, and reflection.

What happens during the absorption of sound?

The sound turns into heat.

What does scattering refer to in sound behavior?

Scattering refers to sound bouncing off in different directions.

What is acoustic impedance?

Acoustic impedance is how much a tissue resists the sound wave.

What occurs when sound hits a boundary at an angle?

The sound bends, a phenomenon known as refraction.

What is a half-value layer (HVL)?

It is the distance it takes for the sound to lose half its strength.

What happens if the HVL is thick?

If HVL is thick, the sound goes deeper before getting weak.

How does frequency affect the attenuation coefficient?

High frequency = more sound lost (less deep penetration); Low frequency = less sound lost (can go deeper).

What is the impact of smooth surfaces on sound reflection?

Smooth surfaces produce a clear echo (specular reflection).

What does reflection of sound contribute to in medical imaging?

Reflection contributes to creating ultrasound images.

What does a decibel measure in sound?

A decibel measures the comparison of two sound levels using logarithms.

If sound increases by +10 dB, what does this indicate?

It indicates the sound is 10 times stronger.

If sound decreases by -10 dB, what is the implication?

It means the sound is 10 times weaker.

What is the effect of distance on sound attenuation?

More distance leads to more weakening of sound.

What can be inferred from a high frequency sound in terms of image quality and depth?

High frequency sound gives better images but cannot penetrate deeply.