6. Types of Noise

If you are using SoundSoap, chances are you have run into some sort of undesirable noise in your digital media. You may have encountered camera motor noise, picked up by the built-in microphone in your DV camera – or perhaps you’ve had an annoying hiss as you archive an old audio cassette collection – maybe there’s a 60Hz hum due to a bad cable that was used in a recording. Perhaps you’re removing clicks and crackles from an old LP collection to convert to CD, or make compressed files for use in a portable digital music player. In any case, such noises can be a big distraction from the desired audio signal. It is projects like these that call for the advanced broadband noise, hum, and rumble reduction, click and crackle reduction, and declipping offered by Soundness SoundSoap.

While SoundSoap can do a great deal to reduce noise from a digital file, there may be situations in which the desired audio signal is lower than the signal of noise, making it impossible to fully remove the noise. In cases like this, SoundSoap may not entirely remove the noise, but may be able to significantly reduce its presence.

The types of noise that SoundSoap is designed to reduce are outlined below:

Broadband Noise

"Broadband Noise" refers to a type of noise that is composed of a broad range of frequencies. Tape hiss, air-conditioner noise, white noise, and pink noise are common examples of “broadband” noise.


Hum 

"Hum" refers to a type of noise that is typically composed of a single frequency, such as 60 Hz.  Hum is often associated with audio equipment being used on faulty electrical circuits, equipment that is not properly grounded, or even electrical power cables being in close proximity to audio signal cables.


Rumble

"Rumble" refers to a type of very low-frequency noise, usually occurring at 40 Hz or below. A good example of rumble would be the low frequency noise produced by a turntable motor, that is commonly found in recordings of vinyl records.


Click & Crackle

"Clicks and crackles" are commonly found in recordings made from vinyl records. Clicks are the result of recording (digitizing) a scratch on a vinyl record, and generally have a fairly high level (for a very short period of time). Clicks are audible in a digital recording because of an abrupt change in volume in a very short period of time. Crackles are similar to clicks, but are caused by tiny surface imperfections on a vinyl record. Crackles are quieter, are more densely concentrated than clicks, and produce a sound similar to the sound of something “sizzling” in a frying pan.


Clipping

Clipping is a form of audio distortion that occurs when the signal is overdriven beyond it's maximum volume range, and reduces the sound quality and intelligibility of material.  This commonly occurs when audio is recorded too loud.  http://en.wikipedia.org/wiki/Clipping_(audio)


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