Unit 3: The Seven Parameters of Sound

Vocabulary flashcards covering the seven parameters of sound waves, ultrasound frequency ranges, propagation speed factors, strength parameters, and key relationships from Unit 3.

Parameters of Sound

Measurable quantities that define and describe the characteristics of a sound wave, consisting of frequency, period, propagation speed, wavelength, amplitude, power, and intensity.

Cycle

One complete oscillation of a wave, moving through resting state, compression, resting state, rarefaction, and back to resting state.

Period

The time required to complete one single cycle, symbolized by $T$ and typically expressed in microseconds (\text{̦s}).

Frequency

The number of complete cycles that occur in a specific timeframe (typically per second), symbolized by $f$ and measured in Hertz ($\text{Hz}$), Kilohertz ($\text{kHz}$), or Megahertz ($\text{MHz}$).

Hertz

The unit of frequency representing events or cycles per second, where $1\text{ Hz} = 1\text{ cycle per second}$, $1\text{ kHz} = 1{,}000\text{ cycles per second}$, and $1\text{ MHz} = 1{,}000{,}000\text{ cycles per second}$.

Infrasound

Sound waves with frequencies below the range audible to human hearing, specifically less than $20\text{ Hz}$.

Audible Sound

Sound waves with frequencies within the range audible to human hearing, specifically between $20\text{ Hz}$ and $20\text{ kHz}$.

Ultrasound

Sound waves with frequencies above the range audible to human hearing, specifically greater than $20\text{ kHz}$.

Propagation Speed

The rate at which a sound wave travels through a medium, symbolized by $c$ and expressed in meters per second ($\text{m/s}$) or millimeters per microsecond (\text{mm/}\text{̦s}).

Soft Tissue Average Propagation Speed

The standard average propagation speed of sound in human soft tissue assumed by ultrasound machines, equal to $1540\text{ m/s}$ or 1.54\text{ mm/}\text{̦s}.

Stiffness

The ability of a medium to resist compression (also called Bulk Modulus), which is directly related to sound propagation speed.

Density

The mass per unit volume of a medium, which is inversely related to sound propagation speed.

Bulk Modulus

Another technical term for stiffness, describing a tissue's capacity to resist compression.

Wavelength

The spatial distance or length occupied by one single cycle of a wave, represented by the Greek letter Lambda (̦) and measured in millimeters ($\text{mm}$).

Axial Resolution

The imaging detail resolution along the beam path, which is improved by shorter wavelengths.

Amplitude

The difference between the average value of an acoustic variable and its maximum or minimum change (measured in Pascals, $\text{g/cm}^3$, $\text{mm}$, or $\text{dB}$).

Peak-to-Peak Amplitude

The total change or difference between the maximum peak and minimum trough of an acoustic variable, equal to twice the amplitude.

Power

The rate at which work is performed or energy is transferred, symbolized by $P$ and measured in milliwatts ($\text{mW}$) or watts ($\text{W}$).

Intensity

The concentration of energy in a sound beam, calculated as power divided by beam area and measured in watts per square centimeter ($\text{W/cm}^2$) or milliwatts per square centimeter ($\text{mW/cm}^2$).

Reciprocals

Two numbers or parameters that equal $1$ when multiplied together, such as period ($T$) and frequency ($f$) where $f \times T = 1$.