Decibel （dB）分贝

“The decibel (dB) is a ratio between the strength of one signal (frequency-band-specific power) and the strength of another signal (a baseline level of power in that same frequency band). The decibel scale is convenient because it is robust to many limitations of raw power, such as 1/f power scaling and subject-specific and electrode-specific idiosyncratic characteristics.” (Mike X,Analyzing Neural Time Series Data p. 220) 分贝( dB )是一个信号的强度(频带特定功率)和另一个信号的强度(同一频段内的功率基线水平)之间的比值。分贝刻度是方便的，因为它对原始功率的许多限制稳定，如1 / f功率缩放和特定对象和电极的特异性特征。

“The base unit is called a bel and is the logarithm of a ratio of numbers. Typically, tens of bels are used, hence decibels.” (Mike X,Analyzing Neural Time Series Data p. 220) 基数单位称为bel，是数比的对数。通常使用几十个贝尔，因此分贝表示如下：

“The horizontal bar over baseline indicates the mean across the baseline time period, and t and f are time and frequency points. Note that the baseline has no t subscript, indicating that all time points within a frequency band use the baseline period.” (Mike X,Analyzing Neural Time Series Data p. 220) 基线上的横线表示跨越基线时间段的均值，t和f分别为时间点和频点。注意，基线没有t下标，表示一个频段内的所有时间点都使用基线时段。

“After decibel conversion, the scale and the interpretation of frequency-band-specific power become the change in power relative to baseline rather than the absolute level of power. Because the activity and the baseline within each frequency band are equally affected by 1/f scaling, any frequencyband-specific activity or amplitude level that is constant over time, including background activity, will be removed” (Mike X, Analyzing Neural Time Series Datap. 220) (Mike X, p. 220) 分贝转换后，频段特定功率的大小和解释变成了功率相对于基线的变化，而不是功率的绝对水平。由于每个频段内的活动和基线受到1 / f缩放的影响是相等的，因此将去除任何随时间恒定的特定频段的活动或振幅水平，包括背景活动。