分音器 是 电子滤波器 在音频上的应用。由于市面上大部分单独的扬声器单元无法在人耳可闻的频率范围(20Hz~20kHz)内，将所有频率成分以足够的音压、够低的失真完整重现，多数高传真扬声器会由若干不同扬声器单元组成、分别负责不同频率范围的重现。分音器的功能便是将电子信号依据事先设置的频率范围分离、并输入至相对应的单元，使它们能够如预期般地工作。

依据分音器在信号路径上所在的位置，可分为被动分音器与主动分音器。被动分音器位于功率放大器与扬声器之间，主动分音器则位于功率放大器之前。主动分音器又可根据信号处理的模式分为模拟与数字两种，数字主动分音器通常能提供除分音以外的功能如：限制、延迟、等化等功能。

Audio crossovers are a class of electronic filter used in audio applications. Most individual loudspeaker drivers are incapable of covering the entire audio spectrum from low frequencies to high frequencies with acceptable relative volume and absence of distortion so most hi-fi speaker systems use a combination of multiple loudspeaker drivers, each catering to a different frequency band. Crossovers split the audio signal into separate frequency bands that can be separately routed to loudspeakers optimized for those bands.