A | Attenuation, loss of db |

B | Magnetic flux density in gap |

Bl | Electro-magnetic force factor |

BL | Driver motor strength |

c | Propagation velocity of sound at STP, approx. 342 m/s |

Cab | Acoustic compliance of air in the enclosure |

Cas | Acoustical equivalent of Cms |

Cmes | The electrical capacitive equivalent of Mms |

Cms | The driver's mechanical compliance (reciprocal of stiffness) |

D | Effective diameter of driver |

F3 | -3 dB cutoff frequency |

Fb | Enclosure resonance (usually for reflex systems) |

Fc | System resonance (usually for sealed box systems) |

Fs | Driver free air resonance. This is the point at which driver impedance is maximum |

l | Length of wire immersed in magnetic field |

Lces | The electrical inductive equivalent of Cms |

Le | Driver inductance (voice coil, mainly) |

Levc | Driver voice coil inductance |

Mas | Acoustical equivalent of Mms |

Mms | The driver's effective mechanical mass (including air load) |

n0 | The reference efficiency of the system |

p | Density of air at STP 1.18 kg/m^3 (rho) |

Pa | Acoustical power |

Pe | Electrical power |

Q | Ratio of reactance to resistance (series circuit), or resistance to reactance (parallel circuit) |

Qa | The system's Q at Fb, due to absorption losses |

Qec | The system's Q at resonance (Fc), due to electrical losses |

Qes | The driver's Q at resonance (Fs), due to electrical losses |

Ql | The system's Q at Fb, due to leakage losses |

Qmc | The system's Q at resonance (Fc), due to mechanical losses |

Qms | The driver's Q at resonance (Fs), due to mechanical losses |

Qp | The system's Q at Fb, due to port losses (turbulence, viscosity, etc.) |

Qtc | The system's Q at resonance (Fc), due to all losses |

Qts | The driver's Q at resonance (Fs), due to all losses |

Ras | Acoustical equivalent of Rms |

Re | Driver DC resistance (voice coil, mainly) |

Revc | DC resistance of the voice coil only |

Res | The electrical resistive equivalent of Rms |

Rg | Amplifier source resistance (includes leads, crossover, etc.) |

Rms | The driver's mechanical losses |

SAF | Spouse Acceptance Factor |

Sd | Effective piston radiating (surface) area of driver |

Vab | The volume of air having the same acoustic compliance as the enclosures |

Vas | The volume of air having the same acoustic compliance as the driver suspension: Cms |

Vb | Net internal volume of enclosure |

Vd | Maximum linear volume of displacement of the driver (product of Sd times Xmax) |

Xmax | Maximum peak linear excursion of driver |

Z | Total driver impedance |