In 对比 to most 'musical' 声 which have a definite 音高 and a predominantly 谐/泛音 频谱 噪 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 may be considered 限制 to that of 人类 听觉 As will be seen it is 可能 to speak of 噪 限制 to a variety of 带宽

It is usual to 用 类比 to visible light when discussing different 种类 of 噪 Thus 噪 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 will be 听 as a 高 嘶嘶声 声波

By passing white 噪 through a 滤器 different 'colours' can be obtained 'Pink noise' results if white 噪 is passed through a 次低通 滤器 Whereas white 噪 has 相等 power at all 频率 pink 噪 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 源 - Richard Dobson 1992 A 字典 of 电子 and 算機/计算机 樂/乐 技术 牛津 University Press