Sound Waves and Their Properties

A sound wave is a pattern of disturbance caused by energy traveling through a medium.

Sound travels fastest in solids, slower in liquids, and slowest in gases.

Frequency is the number of compressions and rarefactions that occur per unit time.

<p>The human ear can hear sounds in the range of roughly 20 Hz to 20 KHz.</p> Signup and view all the answers

<p>The wavelength can be calculated using the formula: $v = f \cdot \lambda$, where $v$ is the velocity of sound, $f$ is the frequency, and $\lambda$ is the wavelength.</p> Signup and view all the answers

<p>Infrasound refers to sound frequencies below 20 Hz.</p> Signup and view all the answers

<p>Compressions and rarefactions represent local increases and decreases in pressure relative to atmospheric pressure.</p> Signup and view all the answers

<p>The wavelength is approximately 0.33 m, calculated using the formula $\lambda = v/f$.</p> Signup and view all the answers

<p>Common symptoms include respiratory impairment, aural pain, fear, visual hallucinations, and chills.</p> Signup and view all the answers

<p>Seismocardiograms measure the micro-vibrations produced by heart contractions in the infrasonic range.</p> Signup and view all the answers

<p>Ultrasound provides more information than X-rays and poses less risk to the fetus.</p> Signup and view all the answers

<p>Sound intensity is the energy carried by the wave per unit area and time, influenced by the acoustic impedance of the medium.</p> Signup and view all the answers

<p>Loudness is determined by the intensity of the sound wave that produces sensation in the ear.</p> Signup and view all the answers

<p>A portion of the sound wave is reflected while another portion is transmitted through the interface.</p> Signup and view all the answers

<p>If Z1 equals Z2, there is no reflected wave, and transmission to the second medium is complete.</p> Signup and view all the answers

<p>A large difference in acoustic impedance results in high reflection and low transmission of sound.</p> Signup and view all the answers

<p>A modern stethoscope consists of a bell, diaphragm, tubing, and earpieces.</p> Signup and view all the answers

<p>The bell must have a certain size and diaphragm tension to resonate at the natural frequency of the sounds being picked up.</p> Signup and view all the answers

<p>Ultrasound in medical applications ranges from 20kHz to 1GHz.</p> Signup and view all the answers

<p>A transducer converts electrical energy into mechanical energy (ultrasound) and vice versa, often using the piezoelectric principle.</p> Signup and view all the answers

<p>The piezoelectric principle allows a crystal to vibrate when an AC voltage is applied, generating ultrasound waves.</p> Signup and view all the answers

<p>SONAR uses ultrasound pulses transmitted into the body to generate images of soft tissue structures.</p> Signup and view all the answers

<p>Gel or water is used to eliminate air and create good impedance matching between the transducer and skin.</p> Signup and view all the answers

<p>Ultrasound echoes are detected as weak signals that are amplified and displayed on an oscilloscope.</p> Signup and view all the answers

<p>The focal zone enhances image resolution by concentrating the ultrasound beam in a specific area.</p> Signup and view all the answers

<p>Acoustic impedance causes some ultrasound waves to be reflected back when they meet a boundary between two tissues with different impedances.</p> Signup and view all the answers

<p>Refraction is the change in direction of ultrasound waves as they pass from one tissue type to another with different sound velocities.</p> Signup and view all the answers

<p>Attenuation reduces the intensity of the ultrasound beam as it propagates through tissue, leading to a potential loss of image quality.</p> Signup and view all the answers

<p>There is often a trade-off between achieving high spatial resolution and ensuring deep tissue penetration.</p> Signup and view all the answers

<p>Thicker liquids help eliminate air bubbles and facilitate better transmission of ultrasound waves into the tissue.</p> Signup and view all the answers

<p>Perpendicular reflection produces a stronger echo signal, which is crucial for obtaining high-quality images.</p> Signup and view all the answers

<p>The quality is determined by the interactions of the acoustic wave with body tissues, including spatial resolution, attenuation, and reflection.</p> Signup and view all the answers

<p>A smooth surface leads to low scattering and produces a good image, while a rough surface causes high scattering and results in a bad image.</p> Signup and view all the answers

<p>A-mode ultrasound involves sending waves into the body and measuring the time taken for echoes to return from tissue interfaces, which indicates depth.</p> Signup and view all the answers

<p>A shift greater than 3 mm indicates an abnormal finding in echo encephalography, which may suggest the presence of a brain tumor.</p> Signup and view all the answers

<p>The two main applications are diagnosing eye diseases and biometry, which involves measuring distances within the eye.</p> Signup and view all the answers

<p>B-mode ultrasound provides two-dimensional images by moving the transducer, while A-mode produces one-dimensional depth information.</p> Signup and view all the answers

<p>M-mode ultrasound is used to study the motion of organs, particularly heart valves, combining 2D imaging with motion analysis.</p> Signup and view all the answers

<p>High frequency is used in ophthalmology because it produces better resolution, as there is minimal energy absorption by the small eye structures.</p> Signup and view all the answers

<p>The depth is calculated using the formula Depth = Velocity x Time, where the speed of sound in soft tissue is 1540 m/s.</p> Signup and view all the answers

A wave pattern created by energy moving away from a source. Think of dropping a pebble in water and seeing the ripples spread outwards.

A measure of how frequently a sound wave oscillates (compresses and expands) per second. Higher frequency means more oscillations in a given time.

The distance between two successive peaks (compressions) or troughs (rarefactions) of a sound wave. It's directly related to frequency; higher frequencies have shorter wavelengths.

The range of sound wave frequencies that humans can perceive, typically between 20Hz and 20kHz.

Sound waves with frequencies below 20Hz, which are too low for humans to hear. Examples include earthquakes and atmospheric pressure changes.

Sound waves with frequencies above 20kHz, which are too high for humans to hear. Used in medical imaging and other applications.

The speed of sound in a medium depends on the density and elasticity of the medium. Sound travels fastest in solids, then liquids, and slowest in gases.

Sound waves can bounce off surfaces (reflection) or pass through them (transmission). The amount of reflection or transmission depends on the properties of the materials involved.

A measure of how much energy a sound wave carries per unit area and time.

The ratio of reflected sound intensity to incident sound intensity.

The property of a material that resists the passage of sound waves. Measured in units of kg/(m²*s).

The sensation of a sound's loudness, determined by its intensity.

A measure of how high or low a sound is perceived, determined by its frequency.

The study of the micro-vibrations produced by the heart, which are in the infrasonic range.

The area where the ultrasound beam is focused, resulting in the highest image resolution and clarity.

The bending of sound waves as they pass from one tissue to another with different densities. This can cause distortion in the image.

The ability to distinguish between two closely spaced objects. It's influenced by the focal zone and wavelength of the ultrasound wave.

The reduction in intensity of the ultrasound wave as it travels through tissue. This can reduce the image quality.

The sound wave bouncing back from the tissue boundary, creating the echo signal that forms the ultrasound image.

The sound wave passing through the tissue boundary, potentially causing artifacts in the image due to refraction.

The quality of the ultrasound image is determined by the interaction of the sound waves with the body tissue. Factors influencing quality include spatial resolution, attenuation, reflection and transmission.

A medical device that amplifies sounds from the body, like heartbeats or lung sounds.

The natural frequency of a stethoscope's bell depends on its diameter and the tension of its diaphragm. It determines which sounds are amplified most effectively.

A device that uses ultrasound waves to create images of inside the body, often used for medical diagnosis.

A device that converts electrical energy into mechanical energy (ultrasound) and vice versa. It's the heart of ultrasound machines.

The mechanism by which some materials (like crystals) convert electrical energy into mechanical vibrations (sound waves) and vice versa. It's fundamental to ultrasound generation.

The transducer, acting like a tiny piston, creates areas of high pressure (compression) and low pressure (rarefaction) in the body's tissues, generating ultrasound waves.

Ultrasound pulses are sent into the body, and the echoes returning from different tissues are detected and used to create images.

A-mode ultrasound uses a single beam to measure the depth of structures by sending sound waves and recording the time it takes for the echoes to return. The depth is proportional to the time, using the assumed speed of sound in tissue.

A-mode ultrasound is used to detect brain tumors by comparing echo patterns on the left and right sides of the head. Changes in the echoes, especially a shift in the middle structure, can indicate abnormalities.

A-mode ultrasound, with its high frequency, is used in ophthalmology to measure distances within the eye, such as lens thickness and the distance to the retina.

Ultrasound images in B-mode are two-dimensional representations of the internal structures of the body. The transducer moves across the area of interest, creating a picture based on the strength of the echoes from different tissues.

B-mode is used to visualize the internal structure of various parts of the body such as the eye, liver, breast, heart, and fetus. It can show sizes, locations, and changes over time of these structures.

M-mode ultrasound combines the features of A-mode and B-mode. The transducer is stationary (like in A-mode) but the echoes are displayed as dots (like in B-mode). The result is a dynamic image of the movement of structures, primarily used to study the heart and heart valves.

High frequency ultrasound is used in ophthalmology because it produces better resolution for visualizing small structures in the eye, and absorption of the sound energy is less significant because the eye is small and there is no bone to absorb much of the sound.

Smooth surfaces reflect sound waves in a uniform way, resulting in good image quality. Rough surfaces scatter sound waves in many directions, leading to poor image quality.