Reducing Noise in Audio FilesWritten by Ross MacIver
The beauty of digital audio is its promise of pristine quality. No clicks, hiss or scratches that were norm of vinyl and tape recordings. That’s not to say that all digital audio is noise-free. Far from it. Poor recordings can still be made in digital medium and recordings that have been transferred from analog (vinyl records or cassettes) to digital will retain some of their noise.Fortunately, cleaning up digital audio is a fairly easy process. There are many software packages on market specifically designed for reducing specific types of noise in digital recordings. Not all of them are suitable for all types of noise, so it’s important to analyze type of noise you are trying to get rid of. Most noise reducing software has a function for removing background hiss. This works by capturing a profile of background noise. The profile is used to create a filter that matches characteristics of noise. To use this function you must select a quiet section of audio to get a sample of noise you want to reduce. A good place to take your sample from is between songs or first second or two before audio actually starts. The sample does not have to be long – half a second is all you need – but it can’t be music or voice – it should represent a silent section. This noise profile will help you to reduce exactly right kind of noise from your audio recording. It is useful for reducing background hiss, but clicks and pops need another kind of processing.
| | How to use MP3Written by Ross MacIver
MP3 is most popular compression format for audio files. In this article, we will take a look at how MP3 works and how you can make your own MP3 files.Uncompressed audio files are very large. A 1-minute CD quality stereo song requires approximately 10 MB of hard disk space. Without compression to reduce this size, relatively few songs would be able to be stored on a computer hard drive, and compact devices like portable MP3 players would not exist, or would cost thousands of dollars. The same one-minute audio file can be encoded in MP3 format and only require about 1 MB of disk space. This amazing reduction in file size is accomplished by discarding some of audio data that is outside hearing range of typical listener. An MP3 file will sound almost as good as original CD but file size will be about one-tenth. There is a balance between how much audio data can be removed and quality of sound. The most common MP3 compression uses 128 kilobits per second (kbps), but many people claim there is a noticeable amount of distortion at this setting. For people with critical listening requirements, 160 kbps is minimum setting – it produces files which are slightly larger than 128 kbps but sound is closer to CD quality. Lower settings such as 96 kbps or 64 kbps introduce noticeable noise into audio. They are suitable for spoken voice recordings but not for music.
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