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