公开(公告)号：US06487257B1

公开(公告)日：2002-11-26

申请号：US09289554

申请日：1999-04-12

申请人： Harald Gustafsson ,  Ingvar Claesson ,  Sven Nordholm

发明人： Harald Gustafsson ,  Ingvar Claesson ,  Sven Nordholm

IPC分类号： H04B1500

CPC分类号： G10L21/0208

摘要： For purposes of noise suppression, spectral subtraction filtering is performed in sample-wise fashion in the time domain using a time-domain representation of a spectral subtraction gain function computed in block-wise fashion in the frequency domain. By continuously performing time-domain filtering on a sample by sample basis, the disclosed methods and apparatus avoid block-processing delays associated with frequency-domain based spectral subtraction systems. Consequently, the disclosed methods and apparatus are particularly well suited for applications requiring very short processing delays. In applications where only stationary, low-energy background noise is present, computational complexity is reduced by generating a number of separate spectral subtraction gain functions during an initialization period, each gain function being suitable for one of several predefined classes of input signal (e.g., for one of several predetermined signal energy ranges), and thereafter fixing the several gain functions until the input signal characteristics change.

摘要翻译： 为了噪声抑制的目的，在时域中以采样方式执行频谱减法滤波，使用在频域中以块方式计算的频谱减法增益函数的时域表示。 通过以样本为基础连续执行时域滤波，所公开的方法和装置避免了与基于频域的谱减法系统相关的块处理延迟。 因此，所公开的方法和装置特别适用于需要非常短的处理延迟的应用。 在仅存在静止的低能量背景噪声的应用中，通过在初始化周期期间产生多个单独的频谱减法增益函数来减少计算复杂度，每个增益函数适用于若干预定义类别的输入信号之一（例如， 对于几个预定信号能量范围中的一个），然后固定多个增益函数直到输入信号特性改变。

公开(公告)号：US06459914B1

公开(公告)日：2002-10-01

申请号：US09084503

申请日：1998-05-27

申请人： Harald Gustafsson ,  Ingvar Claesson ,  Sven Nordholm

发明人： Harald Gustafsson ,  Ingvar Claesson ,  Sven Nordholm

IPC分类号： B13

CPC分类号： G10L21/0232 ,  G10L21/0264

摘要： Methods and apparatus for providing speech enhancement in noise reduction systems include spectral subtraction algorithms using linear convolution, causal filtering and/or spectrum dependent exponential averaging of the spectral subtraction gain function. According to exemplary embodiments, successive blocks of a spectral subtraction gain function are averaged based on a discrepancy between an estimate of a spectral density of a noisy speech signal and an averaged estimate of a spectral density of a noise component of the noisy speech signal. The successive gain function blocks are averaged, for example, using controlled exponential averaging. Control is provided, for example, by making a memory of the exponential averaging inversely proportional to the discrepancy. Alternatively, the averaging memory can be made to increase in direct proportion with decreases in the discrepancy, while exponentially decaying with increases in the discrepancy to prevent audible voice shadows.

摘要翻译： 用于在降噪系统中提供语音增强的方法和装置包括使用线性卷积，频谱减法增益函数的因果滤波和/或频谱依赖指数平均的频谱减法算法。 根据示例性实施例，基于噪声语音信号的频谱密度的估计与噪声语音信号的噪声分量的频谱密度的平均估计之间的差异来平均频谱减法增益函数的连续块。 连续增益功能块被平均化，例如使用受控指数平均。 提供控制，例如，通过使指数平均值与差异成反比的记忆。 或者，可以使平均存储器随着差异的减小而成正比地增加，同时随着差异的增加呈指数衰减，以防止可听见的声音阴影。