6 Waves and Sound in Biology and Medicine Free Online FlashCards

What is an oscillation?

An oscillation is repeated motion about an equilibrium position.

What kind of wave is sound?

Sound is a mechanical, longitudinal wave: particles in its medium oscillate back and forth in the direction the wave travels, creating compressions and rarefactions.

What is the typical human hearing range?

Humans typically hear frequencies from about 20 Hz to 20,000 Hz, though the range varies among people and often narrows with age.

What is ultrasound?

Ultrasound is sound above the upper limit of human hearing, about 20 kHz. Diagnostic ultrasound commonly uses frequencies in the megahertz range.

How does Doppler ultrasound assess blood flow?

Doppler ultrasound uses changes in the frequency of echoes from moving blood cells to assess blood flow.

How are frequency and period related?

Frequency is the reciprocal of period: $f=\frac{1}{T}$.

How are wave speed, frequency, and wavelength related?

Wave speed, frequency, and wavelength are related by $v=f\lambda$.

How does sound vibration become a neural signal?

The outer ear collects sound; the eardrum and middle-ear bones transmit vibration to cochlear fluid. Hair-cell signals then travel along the auditory nerve to the brain.

How does the cochlea help distinguish pitch?

Different regions of the cochlea respond most strongly to different frequencies, supporting pitch discrimination.

What does an ultrasound transducer do?

A transducer converts electrical pulses into sound and returning echoes back into electrical signals.

Why is coupling gel used in ultrasound?

Coupling gel removes the air gap between the probe and skin, helping sound transmit into the body instead of reflecting at the gap.

What affects sound reflection at a tissue boundary?

At tissue boundaries, some sound reflects and some continues onward. The amount of reflection depends in part on the difference in acoustic impedance between the tissues.