Reason是由瑞典軟體公司Propellerhead Software所開發的音樂製作軟體。它模擬成架的硬體合成器、取樣機、訊號處理器、編曲機以及混音器。Reason可以作為一個完整的音樂工作室使用，也可以被其他編曲軟體使用當作虛擬樂器插件。

The bigger rack
Your Reason rack just got bigger. All new Reason version 4 comes equipped with a brand new sequencer, a revolutionary groove tool, a stunning arpeggiator and a synth to end all synths. Welcome to Reason version 4 - the bigger rack.
New synthesizer
A multi-synthesis synthesizer with six oscillator types, four different filters, a step sequencer and a modulation matrix. Fully routable. Fully automatable. Fully everything.
New arpeggiator
A monophonic arpeggiator with multiple play modes, an insert function and a pattern section. And then some.
New sequencer
Reason's new revamped sequencer now features multiple track lanes, vector automation, dedicated device tracks, clips, count-in and more. A lot more.
New groove
A realtime, 32-channel timing and groove handling mixer. Applies non-destructive, freely editable grooves to Reason's sequencer tracks.