在信号与系统学科中，脉冲响应（Impulse response，或叫冲激响应）一般是指系统在输入为单位冲激函数时的输出（响应）。对于连续时间系统来说，冲激响应一般用函数来表示，相对应的输入信号，也就是单位冲激函数满足狄拉克δ函数的形式，其函数定义如下：

并且，在从负无穷到正无穷区间内积分为1：

对于离散时间系统来说，冲激响应一般用串行来表示，相对应的离散输入信号，也就是单位脉冲函数满足克罗内克δ的形式，在信号与系统科学中可以定义函数如下：

In signal processing, the impulse response, or impulse response function (IRF), of a dynamic system is its output when presented with a brief input signal, called an impulse. More generally, an impulse response refers to the reaction of any dynamic system in response to some external change. In both cases, the impulse response describes the reaction of the system as a function of time (or possibly as a function of some other independent variable that parameterizes the dynamic behavior of the system).