Simple Explanation

The total “resistance” a device—like a speaker—offers to the flow of electrical current in an audio system.

Concise Technical Definition

The total opposition to alternating current (AC) in a circuit, combining resistance and frequency-dependent reactance, measured in ohms (Ω).

Layman-Friendly Analogy

Like friction in a pipe—impedance slows down the flow of electrical “water” through a speaker, and that resistance changes depending on the type and speed of flow.

Industry Usage Summary

Impedance is essential when matching speakers to amplifiers. Most speakers are rated at 4, 6, or 8 ohms; mismatches can lead to distortion, overheating, or reduced sound quality.

Engineering Shortcut

Z=R+jXZ = R + jXZ=R+jX — resistance plus reactance; varies with frequency; measured in ohms.

Full Technical Explanation

Impedance is a complex, frequency-dependent measure of how much a component resists the flow of AC (alternating current). It is the combination of resistance (which opposes current at all frequencies) and reactance (which varies with frequency due to capacitors and inductors). In audio systems, impedance plays a key role in how electrical signals are transferred between components like amplifiers and loudspeakers. Speaker impedance ratings—typically between 2 ohms and 16 ohms—must be matched to an amplifier's output capacity to ensure proper power delivery, prevent distortion, and avoid damage. Because impedance changes with frequency, it's also important for determining how evenly a speaker performs across the audible spectrum.