Simple Explanation

When two sounds or signals are working together in sync, reinforcing each other.

Concise Technical Definition

A condition in which two or more waveforms have the same frequency and their peaks and troughs align in time.

Layman-Friendly Analogy

Like two people jumping on a trampoline at the same time—everything lines up and adds together.

Industry Usage Summary

Crucial for speaker and signal alignment; when speakers are in-phase, sound is full and clear—out-of-phase signals can cancel each other and weaken the sound.

Engineering Shortcut

Signals aligned in time; peaks and zero-crossings match.

Full Technical Explanation

In-phase refers to the condition where two or more audio signals or waveforms have synchronized timing—meaning their peaks, troughs, and zero-crossings occur at the same time. This phase alignment allows the waveforms to constructively interfere, reinforcing each other and resulting in increased amplitude and clarity. In audio systems, maintaining phase coherence between channels (especially left and right or multiple speakers) is essential for proper imaging, soundstage, and bass response. When signals are out-of-phase, they may cancel each other, resulting in thin or hollow sound. Proper wiring and speaker placement ensure in-phase playback. See also: Out-of-Phase.