Editing Thiele/Small parameters (section)

==Other parameters==

*<math>Z_{\rm max}</math> – The impedance of the driver at <math>f_{\rm s}</math>, used when measuring <math>Q_{\rm es}</math> and <math>Q_{\rm ms}</math>.
:<math>Z_{\rm max} = R_e\left(1+\frac{Q_{\rm ms}}{Q_{\rm es}}\right)</math>
*<math>EBP</math> – The efficiency bandwidth product, a rough indicator measure. A common rule of thumb indicates that for <math>EBP>100</math>, a driver is perhaps best used in a vented enclosure, while <math>EBP<50</math> indicates a sealed enclosure. For <math>50<EBP<100</math>, either enclosure may be used effectively.
:<math>EBP = \frac{f_{\rm s}}{Q_{\rm es}}</math>
*<math>Z_{\rm nom}</math> – The nominal impedance of the loudspeaker, typically 4, 8 or 16 ohms.
*<math>\eta_0</math> – The reference or "power available" efficiency of the driver, in percent.
:<math>\eta_0 = \left(\frac{\rho \cdot  B^2 \cdot l^2 \cdot S_{\rm d}^2}{2 \cdot \pi \cdot c \cdot M_{\rm ms}^2 \cdot R_{\rm e}}\right)\times100\%</math><ref>{{cite book |title=Acoustics |last1=Beranek |first1=Leo L. |last2=Mellow |first2=Tim J. |date=2012 |publisher=Academic Press |isbn=9780123914217 |oclc=811400350}}</ref>
:The expression <math>\rho/2\pi c</math> can be replaced by the value 5.445×10<sup>−4</sup> m<sup>2</sup>·s/kg for dry air at 25 °C.  For 25 °C air with 50% relative humidity the expression evaluates to 5.365×10<sup>−4</sup> m<sup>2</sup>·s/kg.
:A version that is more easily calculated with typical published parameters is:
:<math>\eta_0 = \left(\frac{4 \cdot \pi^2 \cdot f_{\rm s}^3 \cdot V_{\rm as}}{c^3 \cdot Q_{\rm es}}\right)\times100\%</math>
:The expression <math>4\pi^2/c^3</math> can be replaced by the value 9.523×10<sup>−7</sup> s<sup>3</sup>/m<sup>3</sup> for dry air at 25 °C.  For 25 °C air with 50% relative humidity the expression evaluates to 9.438×10<sup>−7</sup> s<sup>3</sup>/m<sup>3</sup>.
*From the efficiency, we may calculate sensitivity, which is the sound pressure level a speaker produces for a given input:
:A speaker with an efficiency of 100% (1.0) would output a watt for every watt of input.  Considering the driver as a point source in an infinite baffle, at one metre this would be distributed over a hemisphere with area <math>2\pi</math>&nbsp;m<sup>2</sup> for an intensity of <math>1/(2\pi)</math> = 0.159155&nbsp;W/m<sup>2</sup>. The auditory threshold is taken to be 10<sup>–12</sup>&nbsp;W/m<sup>2</sup> (which corresponds to a pressure level of 20×10<sup>−6</sup>&nbsp;Pa). Therefore a speaker with 100% efficiency would produce an SPL equal to 10log(0.159155/10<sup>–12</sup>), which is 112.02 dB. 
:The SPL at 1 metre for an input of 1 watt is then: dB<sub>(1 watt)</sub>&nbsp;= 112.02&nbsp;+ 10·log(<math>\eta_0</math>)
:The SPL at 1 metre for an input of 2.83 volts is then: dB<sub>(2.83 V)</sub>&nbsp;= dB<sub>(1 watt)</sub>&nbsp;+ 10·log(8/<math>R_e</math>) = 112.02&nbsp;+ 10·log(<math>\eta_0</math>) + 10·log(8/<math>R_e</math>)