各位同学：

本周的作业与原定的作业相比有些变化，最终版本请见附件。

下周星期六将进行第一课的考试。具体考试内容较原定的也有些变化，请见附件。

谢炜（老师）

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９月１８日的作业和原定的一样，没有变化。        

                                                    谢炜（老师）       ０９/18/2010     

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1. Download audacity installer from: http://audacity.sourceforge.net/download/windows

2. Download file lame_enc.dll from below.

3. Install audacity and save the attached file lame_enc.dll into the installation folder, which by default is "C:\Program Files\Audacity\".

4. Adjust your windows recording volume

    4.1 plug in your micphone

    4.2 start -> control panel-> sound and audio devices -> advanced -> options -> properties -> recording You may have to choose the proper mixer device to enable "recording" button. make sure micphone is selected and then click "OK".

    4.3 In the Recording control window make sure "microphone" is selected.

5. Start audacity, click the record button and speak into the micphone. Adjust the microphone volume if necessary.

6. Stop recording, click file->export as mp3 and select a file name. If it complains about the lame_enc.dll file, point it to the file you have just saved. You only need to do this once.

7. Controlling the file size in audacity: click menu edit -> preference

      7.1 goto "Quality" tab, set "Default Sample Rate" to 22050Hz, "Default Sample Format" to 16-bit.

      7.2 goto "file format" tab, set "bit rate" to 32