Acoustics/formulas/Electro acoustic efficiency

This formula is a template, for inclusion into pages about Acoustics. Use the following syntax to include it:

{{:Acoustics/formulas/Electro acoustic efficiency}}

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$\eta \approx 1-\frac{1}{1+k_{eff}^2{Q}_E{Q}_L}-\frac{1}{1+\frac{Q_{m0}}{Q_L}}$