🔑 Ultrasound Sound Wave Parameters — Master Table

Parameter	Definition	Units	Determined By	Adjustable?	Key Relationships
Period	Time for 1 cycle to pass	Seconds (µs)	Sound Source	❌ No	Period × Frequency = 1
Frequency	Cycles per second	Hertz (Hz), MHz	Sound Source	❌ No*	↑ Frequency = ↓ Wavelength, ↑ Resolution
Amplitude	Wave strength from baseline to peak	dB, Pascals, cm, g/cm³	Sound Source	✅ Yes	Power ∝ Amplitude², ↓ with depth
Power	Energy per second	Watts (W)	Sound Source	✅ Yes	Power ∝ Amplitude², ↓ with depth
Intensity	Power per unit area	W/cm²	Sound Source	✅ Yes	Intensity ∝ Power ∝ Amplitude²
Wavelength	Physical length of one cycle	mm or m	Source & Medium	❌ No	Wavelength = Speed / Frequency
Propagation Speed	Speed of sound through a medium	m/s or mm/µs	Medium only	❌ No	↑ Stiffness = ↑ Speed, ↑ Density = ↓ Speed

⚠️ *Frequency is indirectly adjustable by switching the transducer.

---

🧠 Bigness Parameters Recap

These three define the “strength” of the sound wave:

• Amplitude
• Power
• Intensity

✅ All are adjustable by the sonographer
❌ All decrease with depth
⚖️ Balancing them optimizes image quality & safety

---

🧪 Exam & Clinical Key Formulas

• Period × Frequency = 1
• Power ∝ Amplitude²
• Intensity ∝ Power ∝ Amplitude²
• Wavelength = Propagation Speed / Frequency
• Soft Tissue Rule of Thumb:
  Wavelength (mm) = 1.54 / Frequency (MHz)