如何计算音频分贝水平？ [英] How can I calculate audio dB level?

问题描述

欲计算与计算机的麦克风的房间噪声水平。我记录噪声的音频文件，但我怎么能计算噪声分贝水平？

I want to calculate room noise level with the computer's microphone. I record noise as an audio file, but how can I calculate the noise dB level?

我不知道如何下手！

推荐答案

所有previous的答案，如果你想有一个技术上准确或科学价值的答案是正确的。但是，如果你只是想比较响度的一般估计，就像如果你要检查狗狗是否吠叫或婴儿是否在哭，并要指定以dB为单位的门槛，那么它是一个相对简单的计算。

All the previous answers are correct if you want a technically accurate or scientifically valuable answer. But if you just want a general estimation of comparative loudness, like if you want to check whether the dog is barking or whether a baby is crying and you want to specify the threshold in dB, then it's a relatively simple calculation.

许多波形文件编辑器在分贝垂直缩放。没有校准或参考测量，只是一个简单的计算：

Many wave-file editors have a vertical scale in decibels. There is no calibration or reference measurements, just a simple calculation:

dB = 20 * log10(amplitude)

在这种情况下的振幅pssed为0和1之间的数，其中1重presents在声音文件中的最大幅值的前$ P $。例如，如果你有一个16位的声音文件，幅度可以高达32767。所以，你只需32767将样本（我们只与绝对值工作，正数。）所以，如果你有一个浪潮峰在14731，则：

The amplitude in this case is expressed as a number between 0 and 1, where 1 represents the maximum amplitude in the sound file. For example, if you have a 16 bit sound file, the amplitude can go as high as 32767. So you just divide the sample by 32767. (We work with absolute values, positive numbers only.) So if you have a wave that peaks at 14731, then:

amplitude = 14731 / 32767
          = 0.44

dB = 20 * log10(0.44)
   = -7.13

但也有认为非常重要的事情，特别是由别人给的答案。

But there are very important things to consider, specifically the answers given by the others.

1）由于约尔格W¯¯米塔格说，分贝是一个相对的测量。既然我们没有校准和引用，此测量值只是相对于自身。而我的意思是，你将能够看到，在这一点上的声音声音文件为3 dB小于在这一点上变得更大，或者这尖峰比背景更响亮5分贝。但是你可以不知道它是在现实生活中多么响亮，不是没有，其他人指的是校准。

1) As Jörg W Mittag says, dB is a relative measurement. Since we don't have calibrations and references, this measurement is only relative to itself. And by that I mean that you will be able to see that the sound in the sound file at this point is 3 dB louder than at that point, or that this spike is 5 decibels louder than the background. But you cannot know how loud it is in real life, not without the calibrations that the others are referring to.

2）也被PaulR和user545125提到：因为你是根据录制的声音评价，你只测量声音的具体位置麦克风，偏麦克风指向的方向，您的硬件的频率响应过滤。几英尺远的地方，与人耳人听会得到一个完全不同的声音水平和不同的频率。

2) This was also mentioned by PaulR and user545125: Because you're evaluating according to a recorded sound, you are only measuring the sound at the specific location where the microphone is, biased to the direction the microphone is pointing, and filtered by the frequency response of your hardware. A few feet away, a human listening with human ears will get a totally different sound level and different frequencies.

3）在不校准硬件，你不能说这声音为60dB或89分贝或什么的。所有这种计算可以给你的声音文件峰如何比较其他峰在同一个声音文件。

3) Without calibrated hardware, you cannot say that the sound is 60dB or 89dB or whatever. All that this calculation can give you is how the peaks in the sound file compares to other peaks in the same sound file.

如果这是你想要的，那么它的罚款，但如果你想要做的事认真，就像确定一个工厂的噪音水平是否对工人的安全，然后听保罗user545125和约尔格。

If this is all you want, then it's fine, but if you want to do something serious, like determine whether the noise level in a factory is safe for workers, then listen to Paul, user545125 and Jörg.

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