This article is from the rec.audio.* FAQ, by with numerous contributions by Bob Neidorff others.

Most of these parameters are well documented in the Loudspeaker

Design Cookbook. (see 12.9) In summary:

Fs Driver free air resonance, in Hz. This is the point at

which driver impedance is maximum.

Fc System resonance (usually for sealed box systems), in Hz

Fb Enclosure resonance (usually for reflex systems), in Hz

F3 -3 dB cutoff frequency, in Hz

Vas "Equivalent volume of compliance", this is a volume of

air whose compliance is the same as a driver's

acoustical compliance Cms (q.v.), in cubic meters

D Effective diameter of driver, in meters

Sd Effective piston radiating area of driver in square meters

Xmax Maximum peak linear excursion of driver, in meters

Vd Maximum linear volume of displacement of the driver

(product of Sd times Xmax), in cubic meters.

Re Driver DC resistance (voice coil, mainly), in ohms

Rg Amplifier source resistance (includes leads, crossover,

etc.), in ohms

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

losses; dimensionless

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

losses; dimensionless

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

dimensionless

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

losses; dimensionless

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

losses; dimensionless

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

dimensionless

n0 The reference efficiency of the system (eta sub 0)

dimensionless, usually expressed as %

Cms The driver's mechanical compliance (reciprocal of

stiffness), in m/N

Mms The driver's effective mechanical mass (including air

load), in kg

Rms The driver's mechanical losses, in kg/s

Cas Acoustical equivalent of Cms

Mas Acoustical equivalent of Mms

Ras Acoustical equivalent of Rms

Cmes The electrical capacitive equivalent of Mms, in farads

Lces The electrical inductive equivalent of Cms, in henries

Res The electrical resistave equivalent of Rms, in ohms

B Magnetic flux density in gap, in Tesla

l length of wire immersed in magnetic field, in meters

Bl Electro-magnetic force factor, can be expressed in

Tesla-meters or, preferably, in meters/Newton

Pa Acoustical power

Pe Electrical power

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

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

Continue to: