Ultrasound Physics with Sononerds Unit 3

The script introduces the topic of the seven parameters of sound, which are essential characteristics of sound waves, including ultrasound. These parameters are frequency, period, propagation speed, wavelength, amplitude, power, and intensity. The video aims to educate on how these parameters define sound waves and their importance in the field of sonography. It emphasizes the need to understand definitions, units, symbols, formulas, and relationships, as well as the impact on sonography. The script also mentions the use of sinusoidal graphs to represent these parameters and the importance of paying attention to labeled units.

This paragraph delves into the concepts of period and frequency, explaining their reciprocal relationship where one is the inverse of the other. The period is defined as the time taken to complete one cycle of a wave, with units typically in microseconds in the context of ultrasound. The frequency, on the other hand, is the number of cycles per second, expressed in hertz (Hz) or its multiples. The script provides a formula that relates period and frequency and discusses how changes in one parameter affect the other. It also touches on the sonographer's role and the impact of these parameters on imaging considerations.

The script explores the range of human hearing, which is from 20 Hz to 20 kHz, and introduces the concepts of infrasound and ultrasound, which are sound waves below and above the audible range, respectively. It explains how age can affect the ability to hear high frequencies and provides an interactive example of the audible range through a video. The paragraph also discusses the historical limitations of adjusting frequencies on older ultrasound machines and the modern capability of transducers to produce a range of frequencies.

This section discusses the importance of frequency in ultrasound imaging, explaining how modern transducers can emit a range of frequencies and how sonographers can adjust the machine to listen for specific frequencies within that range. It highlights the need for sonographers to choose the appropriate frequency for the exam being performed, balancing the need for detail resolution with the ability to penetrate deeper into the body. The paragraph also explains how different frequency ranges are suitable for different imaging depths and anatomical structures.

The script introduces wavelength and propagation speed as two more parameters of sound. Wavelength is the distance a cycle occupies in space, while propagation speed is the rate at which a sound wave travels through a medium. The paragraph explains how these parameters are related and how they are influenced by the properties of the medium through which the sound wave travels. It also discusses the concept of soft tissue average for propagation speed in ultrasound and how this average is used in clinical settings.

This paragraph provides a detailed explanation of how to calculate wavelength and propagation speed using the formulas provided. It discusses the relationship between these parameters and how they can be determined by the frequency of the sound wave and the medium's properties. The script includes examples of how to calculate these parameters for different frequencies and mediums, emphasizing the importance of using consistent units in calculations.

The script discusses how the properties of the medium, such as stiffness and density, affect the propagation speed and wavelength of sound waves. It explains that stiffer mediums allow sound waves to travel faster, while denser mediums slow down the propagation speed. The paragraph also provides examples of different mediums and their propagation speeds, highlighting the importance of understanding these relationships for sonographers.

The final paragraph summarizes the seven parameters of sound, emphasizing their interrelationships and the factors that influence them. It reiterates that amplitude, power, and intensity are directly related and can be adjusted by the sonographer, while period, frequency, wavelength, and propagation speed are determined by the machine and the medium. The script encourages viewers to practice calculating these parameters and to understand their significance in ultrasound imaging.