Low-frequency ultrasound for pulmonary hypertension therapy

Respiratory Research

Table 1 Acoustic parameters of ultrasound in various materials and biological tissues

Tissue	Density, kg/m³	Longitudinal wave velocity, m/s	Acoustic impedance (kg/m² s) × 10⁶	Attenuation coefficient dB/cm at 1 MHz
Air	1.2	330	0.0004	7.50
Water	1000	1480	1.48	0.0022
Blood	1060	1560	1.62	0.15
Skin	1150	1730	1.99	0.35
Liver	1060	1550	1.64	0.50
Heart	1040	1560	1.62	0.52
Skeletal muscles:	1070	1590	1.70
Parallel fibres				1.40
Perpendicular fibres				0.96
Bone	1380–1810	2700–4100	3.75–7.38	15.0
Lung	400	440–500	0.18–0.20	40.0

ISSN: 1465-993X