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我们发现有些文献关于噪声强度评价,对声级求和与平均的计算方法存在一些问题,声级这一声学物理量和一些常用的计量指标(如身高、体重等)不同。从物理概念上看,分贝是贝尔的十分之一,贝尔是一种级的单位。所以,分贝也是级的单位,其对数的底是10的10次方根,量(指真数)与功率成正比。声压平方与功率成正比。因此用于声压时,分贝实际是声压平方级的单位,即分贝可以写做N=log_(10 1/10)~(p~2_1/P~2_0)=1/1/10lg(P_1~2/P_0~2)=10lg(P_1/P_0)~2=20lg(P_1/P_0)。可见声级的计算,并不是声压值的简单迭加,而是声能的迭加,必须按能量迭加法则进行运算,不能直接作常规加减运算。
We found some literature on noise intensity evaluation, the sound level summing and the average calculation method has some problems, the sound level of the acoustic physical quantity and some commonly used measurement indicators (such as height, weight, etc.) different. From a physical point of view, decibel is one-tenth of a bell, Bell is a level unit. Therefore, the decibels are also level units, the logarithm of the base is 10 root of 10, the amount (referring to the real number) is proportional to the power. Sound pressure squared is proportional to power. Therefore, when used for sound pressure, the decibel is actually the square unit of sound pressure, that is, the decibel can be written as N = log_ (10 1/10) ~ (p ~ 2_1 / P ~ 2_0) = 1/1/10 lg 2 / P_0 ~ 2) = 10lg (P_1 / P_0) ~ 2 = 20lg (P_1 / P_0). Visible sound level calculation, not a simple superposition of sound pressure value, but the superposition of sound energy, the law must be based on the energy superposition algorithm, can not be directly as regular addition and subtraction operations.