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The sound pressure level that each speaker generates when driven by a signal voltage of 1 V. The sensitivity is usually stated for a 1-kHz signal. Since current audio devices operate on low supply voltages (e.g., all portable devices, PC sound cards, etc.), their output voltages are commensurately low, in the range of a few volts. To make selecting headphones easier, the sound pressure level is stated for a voltage that every device of this class is assumed to provide. 1 volt has become a generally accepted value. |