Physics - Ch.3: Describing Sound Waves

What are the 7 Parameters of Sound Waves?

• Period

• Frequency

• Amplitude

• Power

• Intensity

• Wavelength

• Speed

Period:

• Definition

• Units

• Determined By

• Adjustable 

• Time it takes wave to vibrate a single cycle or time from start of one cycle to start of next cycle

• Time

• Sound source

• No

Frequency:

• Definition

• Units

• Determined By

• Adjustable

• Number of particular events that occurs in a specific duration of time or number of cycles that occurs in one second

• Per second; Hertz

• Sound source

• No

Sound Waves Frequency:
(what are their ranges in #?)

• Infrasound

• Audible Sound

• Ultrasound

• < 20 Hz

• 20 Hz - 20 kHz

• > 20 kHz

What is the Relationship Between Frequency & Period?

• Inversely related

What is the Special Relationship Between Period & Frequency?

• Reciprocal

• = 1

What are the “Three Bigness Parameters”?

• Amplitude 

• Power

• Intensity

Amplitude:

• Definition 

• Units

• Determined By

• Adjustable 

• Difference between maximum value and average of acoustic variable or minimum value and average value of acoustic variable

• Any acoustic variable: pressure (pascals), density (g/cm3), and particle motion (any distance)

• Sound source

• Yes 

What is the Difference Between Amplitude & Peak-to-Peak Amplitude?

• Amplitude = baseline to top of peak

• Peak-to-Peak Amplitude = minimum (below baseline) to maximum (top of peak)

Power:

• Definition

• Units

• Determined By

• Adjustable

• Rate of energy transfer or rate at which work is performed

• Watts

• Sound source

• Yes

What is the Relationship Between Amplitude & Power? + What is the Mathematical Proportion Between them?

• Directly related

• Power is proportional to amplitude2

Intensity:

• Definition 

• Units 

• Determined By

• Adjustable 

• Concentration of energy in a sound beam

• W/cm2

• Sound source

• Yes

Formula for Intensity

Intensity (W/cm2) = power (w) / area (cm2)

What is the Relationship Between Intensity & Power?
What is the Relationship Between Intensity & Amplitude?

• Directly related 

• Directly related; intensity is proportional to amplitude2

Wavelength: 

• Definition

• Units

• Determined By

• Adjustable

• Distance or length of one complete cycle

• Any length

• Both; sound source and medium

• No

Formula for Wavelength

Wavelength (mm) = 1.54 mm/milisecond / Frequency (MHz)

What is the Difference Between Wavelength & Period?

• Wavelength = distance

• Period = time

What is the Relationship Between Wavelength & Frequency?

• Inversely related

Propagation Speed:

• Definition 

• Units

• Determined By

• Adjustable

• Rate at which a sound wave travels through a medium

• Distance/time

• Medium

• No

Formula for Speed

Speed (m/s) = frequency (Hz) x wavelength (m)

What is the Speed of Sound in Soft Tissue? (name 3 units)

• 1,540 m/s

• 1.54 mm/milisecond

• 1.54 km/s

What Characteristics of a Medium Determine the Speed of Sound in that Medium? (name 2)

• Stiffness

• Density

Stiffness:

• Definition

• What is their relationship?

• Ability of an object to resist compression

• Directly related

Density:

• Definition 

• What is their relationship?

• Relative weight of a material 

• Inversely related

Between Stiffness and Density, Which One Has the Greatest Affect on Speed?

• Stiffness