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Noise Reduction Manual

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Unformatted text preview: You may register via the Sonic Foundry web site or via the telephone. To register, follow the instructions shown in the Registration dialogs. Technical support If you experience problems or have questions while using Noise Reduction, there are a few ways to get the information that you need from Sonic Foundry: web site support, email support, fax support, and telephone support. Web site support Visit our Web site at www.sonicfoundry.com/support. You will find technical information, reference information, program updates, tips and tricks, and a Frequently Asked Questions (FAQ) archive. Email support Send your questions or comments by using the Technical Support Request form found on our web site: www.sonicfoundry.com/support/SupportMail.asp. Our Technical Support Department will respond to you within 36 business hours. CHP. 1 INTRODUCTION 8 Fax support Send your questions or comments via fax 24 hours a day at (608) 250-1745. You will receive a response within 36 business hours. Telephone support Our technical support representatives are available Monday-Friday from 7am to 10pm (CST) at (608) 256-5555. Before You Call Support Before you contact our technical support department, we ask that you do the following: • Check to see if your question may be answered in the manual or online help. For more information, see Tips and Frequently Asked Questions on page 49. • Use a telephone that is near the computer where Noise Reduction is installed. • Make sure you have registered the product. INTRODUCTION CHP. 1 9 CHAPTER Noise Reduction 2 The Sonic Foundry Noise Reduction plug-in is designed to analyze and remove background noise such as tape hiss, electrical hum, and machinery rumble from sound recordings. Unlike a normal filter, Noise Reduction can do so without removing part of the source material. This function is accomplished by separating the audio into its frequency components and using a “noiseprint” to distinguish between unwanted noise and the desired signal. Noiseprint A noiseprint is created by analyzing a portion of the recording where there is no source material, such as during a silent lead-in. Noise Reduction stores frequency and amplitude information about the noise in the recording. Once a noiseprint has been generated, it can be modified by the user to determine what parts of the frequency spectrum to remove. However, this type of manual modification is not usually necessary. Limitations The Noise Reduction algorithm works well to remove constant background noise. Rapidly changing or “erratic” noise such as traffic sounds or vinyl pops are not well suited for this algorithm. The Click and Crackle Removal plug-in is better suited for this type of noise. For more information, see Click and Crackle Removal on page 35. However, different types of noise can be removed by generating a noiseprint for each type. Also, in cases where the noise is of equal or greater volume level than the source material, it can be difficult, if not impossible, to clean up without some resulting audible side effects. CHP. 2 NOISE REDUCTION 10 Removing noise from a recording The Noise Reduction function is a two step process: capturing a noiseprint and removing the noise. Using the Noise Reduction plug-in to remove noise requires different methods of noiseprint gathering depending on the host application you are using. This manual covers the following sound editing programs: • • • • • Sound Forge Vegas Cakewalk Pro Audio Steinberg WaveLab IQS SawPro Using Noise Reduction with Sound Forge 1. Open ACnoise.WAV from the folder where you installed Noise Reduction and select a region that contains only the air conditioner noise. We have created a region in the file for this purpose. 2. Double-click between the region markers to select the data in that region. Select the AC noise 3. Select Sonic Foundry Noise Reduction from the DirectX menu. The default preset contains the parameters that will give you good results. The most important parameter is the Reduce Noise by slider at the top of the dialog that determines the amount of noise attenuation. 4. Click on the Capture noiseprint check box. NOISE REDUCTION CHP. 2 11 5. Press the Preview button on the Noiseprint page. Noise Reduction will make one preview pass through the selection and then loop back to the beginning. After the first pass, Noise Reduction has captured a noiseprint and switched from capture mode to process mode. Process mode means that Noise Reduction is ready to process the sound file. The plug-in is now reducing noise in real-time. However, you are only reducing the noise in your current selection of the ACNoise.wav. Note: D uring capture mode you will not be able to change process properties. 6. Right-click on the blank space below the Real-time check box and choose Select All Data from the pop-up menu. The entire file will now play, allowing you to change parameters and simultaneously listen to the results. 7 Click the OK button on either the General or Noiseprint page to...
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