Estimation of Reverberation Time

The reverberation time of an auditorium or a room is usually defined as the time required to drop 60 decibels below the initial level. The decay of a sharp sound like a hand clap or a finger snap will produce a reverberant decay in the room which can be approximated by an exponential curve. This reverberant decay can be observed by using a microphone with the laboratory interfaces, and measurements of voltage from the microphone at different times can be used to estimate the reverberation time of the room.

一个礼堂或房间的混响时间通常定义为声音从初始电平下降60分贝所需的时间。一个尖锐的声音，如拍手或指 snapping，会在房间内产生混响衰减，这种衰减可以近似地用指数曲线来表示。通过使用麦克风和实验室接口，可以观察到这种混响衰减，通过在不同时间测量麦克风的电压，可以估计房间的混响时间。

Measure the length, width and height of the laboratory room. Typical absorption coefficients for the walls, floor and ceiling will be provided. Use the Sabine Formula calculation to calculate a reverberation time for the room.

计算出的房间混响时间 _________

测量实验室房间的长度、宽度和高度。将提供墙壁、地板和天花板的典型吸声系数。使用Sabine公式计算房间的混响时间。计算机接口的设置：

过程：根据萨宾公式计算混响时间：

2. Scroll down the "Sensors" menu to "Sound Sensor" [the ear icon on the menu] and click-and-drag that icon to the image of the port where your microphone is connected.

向下滚动“传感器”菜单到“声音传感器”[菜单中的耳形图标]，并将该图标拖动到麦克风所连接的端口图像上。

1. Click on "Scope" under the "Displays" menu to display an oscilloscope screen. Click the "Start" button and produce a sound to confirm that you can display a sound waveform.

在“显示”菜单下点击“示波器”，以显示示波器屏幕。点击“开始”按钮，发出声音以确认可以显示声音波形。

2. You will need to experiment with producing a sharp sound and getting a display of it on the scope. Try a hand clap at a half to one meter away from the microphone, or a finger snap if you like that better. It may take some experimentation to get a display. You will need to slow down the horizontal motion of the sweep by clicking on the horizontal scaling display, which may read something like 5ms when you start. Once you are producing a satisfactory display, then click the "Stop" button when one sound burst is displayed before it erases it for the next sweep.

2. 你需要进行一些实验，以产生清晰的声音并在示波器上显示出来。可以尝试在距离麦克风半米到一米处拍手，或者如果你更喜欢手指拍击声的话，也可以尝试。可能需要一些实验才能得到理想的显示效果。你需要通过点击水平缩放显示来减慢水平运动，这可能初始显示为5ms。一旦你产生了满意的显示效果，当一个声音脉冲显示出来后，就点击“停止”按钮，以防止它被下一个扫描清除。

3. Click the data storage button to store that trace of the sound waveform. This button looks like pincers picking up a ball. Then double-click on "Graph" under the "Displays" menu to put a graph on the screen. Drag the icon for your data set over onto the graph to display it. It will appear cluttered with their cute symbols for data points, but you can clean it up by going to the Display/Settings and taking off the "Show data points" , "Show Legend Symbol", and "Show Legend" options.

3. 点击数据存储按钮以存储该声音波形的轨迹。这个按钮看起来像钳子夹起一个球。然后双击“显示”菜单下的“图示”，将图示显示在屏幕上。将你的数据集图标拖到图示上以显示它。它会显得杂乱，因为有那些可爱的数据点符号，但你可以通过进入显示/设置，取消勾选“显示数据点”、“显示图例符号”和“显示图例”选项来清理它。

4. The sound decay will generally not be a neat decay - it will be a jagged set of peaks which diminish with time. You will have to visualize a smooth decay curve and estimate the height of that curve at some point in time. It is also more convenient to visualize a symmetric decay above and below the center line and just measure the full width as shown in the illustration below. Measure the initial height of the burst to record as V₀ and record the initial time T₀. Then pick a convenient time along the horizontal scale and make your best estimate of the height of the decay pattern at that time T to record as voltage V. Since there is considerable uncertainty, try to get 5 different points. If it is not reasonable to sample at five different points on one display, then do another handclap to collect additional sets. Then take the link to the calculation routine and calculate the reverberation time associated with each set of voltage and time data. Average the results of the calculations to get your final estimate of the reverberation time of the room.

4. 声音衰减通常不会是一个光滑的衰减——它将是一系列尖峰，这些尖峰随时间减弱。你需要想象一个光滑的衰减曲线，并在某个时间点估计该曲线的高度。此外，更方便的是在中心线上下对称地可视化一个衰减曲线，并仅测量全宽，如下面的示意图所示。测量爆破的初始高度以记录为V₀，并记录初始时间T₀。然后选择一个方便的时间点，在水平刻度上进行测量，并尽可能估计该时间点衰减模式的高度T，记录为电压V。由于存在相当大的不确定性，尽量获取5个不同的点。如果在一个显示上无法合理地采样五个不同的点，则进行另一次拍手以收集更多的数据集。然后链接到计算程序，计算每个电压和时间数据集的混响时间。对计算结果进行平均，以获得房间的混响时间的最终估计。