Speed of sound various mediums

Air

0.33 mm/ųs

Fat

1.45 mm/ųs

Water

1.48 mm/ųs

Soft tissue (main one)

1.54 mm/ųs

Blood

1.57 mm/ųs

Muscle

1.58 mm/ųs

Bone

4.0 mm/ųs

PZT (electric material of transducers)

4.08 mm/ųs

Steel

5.0-6.0 mm/ųs

Z

Stiffness

Also called impedance

K

Compressibility

C

Propagation speed

Mostly constant

P

Density

f

Frequency

Inversely proportional to wavelength

λ

Wavelength

Inversely proportional to frequency

Proportional to propagation speed

Higher density (p)

Higher stiffness (Z) and faster propagation speed (c )

Higher λ

Constant frequency but higher propagation speed (c )

If medium changes than wavelength changes