来自烟花的噪音水平 - 一个非常不科学的测量！
来自烟花的噪音
This year, Bonfire Night (5th November for anyone who doesn’t know) fell on a Saturday this year and despite the forecast of rain, myself and my colleagues Gill Cussons, Justin Barker and Nigel Palmer braved the weather with the aim of measuring the noise levels at our local fireworks displays.
我们没有列出任何规则，这些规则应该以其他方式从观众区内制定，并且应该代表人们会得到的噪音暴露。
所有测量都是使用的Cirrus optimus red and green sound level meters并且在使用前校准这些校准。所有仪器使用标准挡风玻璃，以减少风对麦克风的影响。
I should also point out that these measurements were taken over a range of different durations and that we didn’t know in what type or size of fireworks would be used.
The display that I measured at was a small village bonfire with, I would guess, around 500 spectactors. This was typical of the events that we visited although the display that Gill measured at was slightly larger.
The noise levels
总共进行了9次测量，持续时间为52秒和19分钟，其中一些是整个显示器（＃5）的测量，只需单个火箭（＃9）即可比较短。
We aimed to get a representative selection of measurements and to cover a range of different fireworks. Here’s a summary of the overall data.
| Â测量 | Duration hh:mm:ss | Laeq（DB） | Lafmax（DB） | LCPeak (dB) |
|---|---|---|---|---|
| â1 | 00:05:44 | 96.3. | 109.8 | 137.2 |
| A2 | 00:13:49 | 94.5 | 109.4 | 136.9 |
| â3 | 00:03:33 | 81.4 | 107.5 | 134.8 |
| â4 | 00:20:42 | 84.0 | 106.5 | 133.5 |
| Â5 | 00:18:57 | 74.9 | 105.0 | 130.9 |
| â6 | 00:00:11 | 92.1 | 100.8 | 130.2 |
| Â77 | 00:02:50 | 80.3 | 101.6 | 126.7 |
| â8 | 00:00:52 | 86.6 | 95.6 | 107.3 |
| Â＃9 | 00:00:04 | 83.9 | 94.7 | 101.4 |
它有多大笑？
As you can see from the table above, the loudest measurement in terms of the C-Weighted Sound Pressure and the LAFmax (Maximum A-Weighted Fast Sound Level) was #1 which was made by Gill over a 5 minute period.
Although none of the measurements had Peak(C) levels above the exposure limits value of 140dB(C), the top three are at or above the upper exposure action value of 135dB(C) Peak.
对于此测量，96.3的整体LAEQ相当于77.1dB（a）的LEP。这不是特别代表，因为测量持续时间很短。
Looking at the next measurement (#2 @ 00:13:49) with a measured LAeq of 94.5dB, we get an equivalent LEP,d of 79.1dB(A) which is just short of the lower exposure action value.
If this noise level continued for an hour, the person exposure would have had a noise exposure that was at the upper exposure action value of 85dB(A) and would be in a situation where noise control measures would have been needed!
频率和所有这些
Much of the excitement from fireworks comes from the audible and physical impact of the explosions as the fireworks detonate. Measurement #1, made by Gill, has the highest LAFmax and LCPeak so I’ve looked at this measurement in a little more detail.
The highest level within this measurement occurred at 20:30:57.25 precisely (or within a 1/16 of a second of that time!) so we can get some very detailed information from the sound level meter at that point.
我们所做的所有测量都是通过设置为记录时间历史或噪声配置文件的最优声级仪表，以1/16秒或1/100秒的速率进行记录，以1：1和1：3 ockave频段信息以1/16秒或62.5ms分辨率存储。
We can dig into the detailed data using the NoiseTools software and by looking for the time at which the LCPeak was recording 137.2dB we can get the 1:1 and 1:3 octave band information at that time.
The graph below shows where the highest levels occurred in the measurement and by zooming in with the NoiseTools software, we can see the exact moment that the dB(C) Peak level got to 137.2.
Zoom in on the loudest part of the measurement
Below are the 1:1 and 1:3 octave band spectra showing the 1/16th second Leq at that time:
1:1 Octave Band Spectra from Fireworks Noise Measurement
1：3来自烟花噪声测量的倍频程频谱谱
如您所见，大多数能量在125,250和500Hz频带中，尽管1：1八度频带数据显示在31Hz的峰值。快速计算表明，此时的等效LAEQ值（使用1：1八度频带数据）是112dB（a）。未达到的等效莱克是116.4dB（a）。
声音录制
Theoptimus green sound level metersused by Gill and Justin have the ability to record audio samples during a measurement. These can be triggered either manually or automatically using level and threshold triggers.
In this application, the audio recordings were started manually. The recordings are downloaded into the NoiseTools software program and can be listened to and analysed using the built-in tools.
An example of this analysis is shown below.
录音分析
Notes & Comments
All of the measurements, apart from one set, were made with a standard microphone capsule.
The optimus red that I used had an MV:200EH high level microphone which was capable of measuring levels up to 170dB.
我用它来看看是否有任何级别会导致仪器过载。幸运的是，我们测量的所有水平都在仪器的正常操作范围内。
Clarke Roberts
He particularly enjoys writing content about product applications, including noise nuisance, occupational noise and environmental noise pollution.
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