Audacity Effects: Amplify (5) – Finding Peak Amplitude

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As explained in “Audacity Effects: Use of Decibels (Log Scale),” sound is representation better in decibel scale, especially if you want to show volume (amplitude) changes.1 Although Audacity’s default view is in linear scale, most of the effects use decibels as parameters, so it is a good thing to know how to quickly find the magnitude of a certain track or certain region in decibels (dbs). Continue reading

Audacity Effects: Amplify (4) – Difference from Normalize

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In Audacity, we normalize to a level, but amplify by a level. However, in the “amplify” effect, there is also an option for you to amplify to a chosen peak amplitude. When this option is used, “amplify” basically functions the same as “normalize,” but only for single track audio.

Amplification by multiple tracks has been covered before when “normalize” is discussed. Here we are just going to show an example illustrating the difference. Continue reading

Audacity Effects: Amplify (3) – Some Clipping Details

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In the previous article we talked about “allow clipping” for “amplify” effect. By checking the “allow clipping” option, you allow the signal to be amplified above the maximum level, so distortion or clipping will occur. In this article, we will examine how data is affected or not affected internally. Continue reading

Audacity Effects: Amplify (2) – Allow Clipping

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When we work with audio in Audacity, we basically work with relative scales. With a particular calibrated system, the linear amplitude of 1.0 (or 0 db in log scale) represents the maximum amplitude before distortion or clipping occurs. While we don’t want our audio to go beyond this amplitude especially during the recording stage, this happens occasionally during editing. Continue reading

Audacity Effects: Amplify (1) – Basic Operations

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The Amplify effect is similar to Normalize effect. Amplify allows you to amplify a track or tracks by a certain level whereas Normalize sets the peak amplitude to a certain level. Optionally, Amplify can also set peak amplitude to a chosen level, in which case it is really the same as Normalize, for single track that is. For multiple tracks, Amplify and Normalize behave differently. Continue reading

Audacity Effects: Normalize (4) – Stereo Channels

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“Normalize” effect is an effect that sets the maximum amplitude to a chosen level (expressed in decibels). For multiple tracks, “normalize” effect treats each track independently, that is, it will set the maximum amplitude of each track to the chosen level.

An example of this use is my recording of instructional videos. I record instructions or explanations that go with slide displays, and I record the sound for each slide separately and keep the audio for each slide in separate tracks. After all recording is done, I edit the audio using Audacity. If I need to adjust the volume to a certain level, I will want the whole audio to have more or less the same volume even if I happen to speak louder or softer during the recording of each track. Continue reading

Audacity Effects: Normalize (3) – Multiple Tracks

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In last article, we talked about the effect of “normalize.” Basically, it takes the maximum amplitude of the signal we are processing, adjusts it to the level that we choose and adjusts the whole signal proportionally. In terms of decibels (db), this simply means adding or subtracting the same amount of db to the whole signal such that the maximum amplitude is at the chosen level.

Next we need to know how Audacity does normalization in a multiple tracks situation. Continue reading

Audacity Effects: Normalize (2) – Setting Maximum Amplitude

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The normalize effect is a simple effect to set maximum amplitude to a chosen level. If you think of any audio system, be it a simple CD player or a complex sound system with lots of equipments, the normalize effect is simply the volume control knob. You turn the knob up and down to turn the volume of the sound up or down. It is just that simple. Continue reading

Audacity Effects: Normalize (1) – DC Offset Removal

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Some people might find it strange that dc offset removed is lumped together with normalization effect. The reason is that in mathematics, normalization usually involves offset shifting and re-distributing of data, and dc removal is the offset shifting part.

In audio recording, dc offset is almost always a hardware problem. Continue reading

Audacity Effects: Use of Decibels (Log Scale)

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Sound intensity is related to pressure, and the unit of pressure is Pascal (abbreviated Pa). However, we don’t normally use Pa in describing sound intensity; we use the unit of decibel (db) instead. It is not necessary to understand all the mathematics involved in the conversion from Pa to db, but some basic understanding of the concept is useful. There are a few reasons why we use db in describing sound. Continue reading