In 对比 to most 'musical' 声音 which have a definite 音高 and a predominantly 谐波（泛音） 频谱 噪音 consists of a 理论 infinite and continuous 范围（排列） of 频率 The 波形 consists 不 of regular 周期 周期 but of 随机性 波动 of 振幅 In the present 语义（上下文） the 频带宽度（带宽） of the 噪音 may be considered 限制 to that of 人类 听觉 As will be seen it is 可能 to speak of 噪音 限制 to a variety of 带宽

It is usual to 使用 类比 to visible light when discussing different 种类 of 噪音 Thus 噪音 which has 相等 强度 at all 频率 is referred to as 'white noise' Because the 人类 耳 is more 敏感 to 高 than to 低 频率 white 噪音 will be 听 as a 高 嘶嘶声 声音

By passing white 噪音 through a 滤波器 different 'colours' can be obtained 'Pink noise' results if white 噪音 is passed through a 次低通 滤波器 Whereas white 噪音 has 相等 power at all 频率 pink 噪音 is 定义 as having 相等 power in each 倍频程（八度） 带/乐队 corresponding more closely to the 响应/反应 of the 耳 Thus the power varies 相反 with 频率 - for this reason it is often referred to as '1/f noise' 类似 'red noise' is referred to as '1/f 平方 noise' the 高 频率 being much more 衰减 than in pink 噪音 源 - Richard Dobson 1992 A 词典 of 电子 and 计算机 音乐 技术 牛津 University Press