Sound Engineer's Pocket Book, 2nd Edition

6  Electromechanical Analogies

Summary of Analogue Quantities, Units, Symbols and Relationships

The table below gives the overall units and dimensions:

Mechanical	Acoustic	Electrical
Mass, M (kg)	Mass, Ma, Inertance	Inductance, H, (Henry)
Force, F (N)	Sound pressure, p	Volts (V)
Displacement, x (m)	–	Charge Q (C)
Velocity, x˙ (m/s)	Volume velocity	Current (Q/s,A),i
Energy, work (J)	joules (J)	joules (J)
Power (W, J/s)	watts (W)	watts (W)
Stiffness, F/x	–	–
Compliance, x/F	Compliance, Ca	Capacitance, C
Frequency, f (l/s,Hz)	–	–
Resistance, Rm	Acoustic resistance, Ra	Resistance R
Temperature (K)	–	Magnetic flux density, B
Length, L	–	–

Impedance relationships

Mechanical impedance,

Specific acoustic impedance, ...