Amplitude

  • 1. INTRODUCTION

In this post we will define the concepts of amplitude and gain. We will also introduce the enveloping edition method we can use in a digital audio edition program (like Soundbooth and Audition). Finally we will also talk about three different edit processes we can apply to sound through this mentioned programs: normalization, inverting and flipping.

First of all we will introduce some concepts that are related to this part of the summary and will help you to understand better the rest of the article. These definitions are written by Luisa Winters and published on AdobePress.com:

  • Decibels (dBs). Units used to measure the intensity of sound: 0dB is near silence; 10dB is 10 times as loud; 20dB is 100 times as loud; 30dB is 1000 times as loud; and so on.
  • Peak amplitude. Is the maximum absolute value of the signal. This is the loudest that it will be.
  • LUFS (Loudness Units relative to digital Full Scale). The European Broadcast Union (EBU) uses the term LUFS. These are absolute units used to measure audio levels. The loudness target level could be -23 LUFS. In conjunction with this they use Loudness Units (LU). LUs are used to show relative level changes (-23 LUFS is 2 LUs lower than -21 LUFS). One unit of LUFS equals one decibel.
  • Dynamic range (DR). Is the difference between the loudest and the quietest part of your audio, and is measured in decibels. Depending on which genre of audio you’re working with, you’ll need to have a wider or narrower DR, so keep this in mind. Classical music, for example, will have a much wider DR than Pop or Rock.” (Luisa Winters)
  • 2. AMPLITUDE

The amplitude of a wave is the distance from the 0 to the highest peak of one cycle. The highest the distance, the louder it will sound. This picture will help you to understand it:

Amplitude

Amplitude

Other important concepts about the interaction of waves we should know are that if we have two or more waves that are in the same phase sounding at the same time they join coming to a wave that is bigger (louder) than the individual ones. You can see it in the next picture:

On the other hand, if we have two equal waves that are completely out of phase they rest themselves and finally there isn’t any sound.

Finally if we have different waves that are on a different phase or don’t have a regular phase the result will be a wave more complex than the first ones:

These examples were originally provided by the Adobe Soundbooth manual.

  • 3. GAIN

Gain is expressed in dB and means and increase. Is important to know the difference between gain and volume. This explanation published on an AdobePress article written by Luisa Winters will make you easily understand this difference:

“Both gain and levels refers to the loudness of the audio. However, gain is the input level of the clips and volume is the output. In recording audio, gain is the first control that the microphone signal goes through a mixer while levels are adjusted after that.” (Luisa Winters)

Adjusting gain to a higher or lower level will help us to make our different music clips to have the volume we need. It is recommended to also adjust the gain of the clip even before adding it on the Timelime of the program we are working with.

To modify the gain of our clips we have two different options. To explain them I will quote this short explanations originally published on the Luisa Winters’ AdobePress article:

  1. Set Gain to: The Set Gain to adjustment affects the net amount of gain by which you are adjusting the clip. You can increase or decrease gain by as much as 96dB.

  2. Adjust gain by: The Adjust Gain by option is similar to the Set Gain to option, but it allows you to add or decrease the net gain amount by incremental amounts. As you enter amounts, the Set Gain to amount automatically adjusts. Set Gain to is absolute, but Adjust Gain by is incremental, meaning that if you adjust it twice by 2dB, you will get an increment of 4dB.

    To find this options on the menu you have to follow this steps: Choose Clip > Audio Options > Audio Gain.

  • 4. NORMALIZE

Luisa Winters defines Normalization with the following words:

“Is the process of changing the overall volume of an audio clip so that you reach (and don’t pass) a target level.” (Luisa Winters)

But i prefer this definition published on this article:

“Normalization increases volume as much as possible without introducing distortion into the file” (Jan Ozer)

This next video will explain how to apply normalization to our clips (and also compression, but we haven’t talked about it yet):

  • 5. ENVELOPE

When using Soundbooth or Audition, envelopes are visual signals that makes it easier to know and modify different settings applied to sound. They don’t really change the original audio file so you won’t lose the original information. They only apply different effects over it. All the images you will find in this part of the article are from the original Adobe Audition manual.

A. Clip Envelope // B. Track Envelope

When using envelopes it’s recommendable to add keyframes so you can modify different parts of the clip with different settings. Between two keyframes the transition can be abrut (using a hold transition) or gradual (using a linear one). You can also apply spline curves.

A. Hold // B. Linear // C. Spline Curve

This steps explained in the Audition manual will help you to learn using keyframes:

Add a keyframe

Do either of the following:

  • Position the pointer over an envelope line. When a plus sign appears, click.
  • Position the playhead where you’d like a track parameter to change. Then click the Add Keyframe icon in the track controls.

Navigate between track keyframes

  1. In the Editor panel, choose a parameter from the Select menu near the bottom of the track controls.
  2. Click the Previous Keyframe or Next Keyframe icon.

Select multiple keyframes for a parameter

  • Right-click any keyframe, and choose Select All Keyframes.
  • Hold down Ctrl (Windows) or Command (Mac OS), and click specific keyframes.
  • Hold down Shift, and click to select a series of keyframes.

Reposition keyframes or the envelope line

  • To reposition selected keyframes, drag them. (To maintain time position or parameter value, hold down Shift and drag.)
  • To reposition a segment of an envelope without creating a keyframe, hold down Ctrl (Windows) or Command (Mac OS), and drag.

Change the transition between two keyframes

  • Right-click the first keyframe, and select Hold Keyframe to abruptly change values, or deselect it to gradually transition from one value to the next.

Apply spline curves to an entire envelope

  • Right click an envelope line, and choose Spline Curves.

Delete keyframes

  • Right-click an envelope line, and choose Delete Selected Keyframes. Or, drag an individual keyframe off a clip or track.”
  • 6. INVERT/FLIP

Inverting changes the polarity of the signal (phase) and normally don’t produce any audible. You only can hear a difference when combining waves: you might invert pasted audio to align it with the existing one and you might invert one channel of the stereo to correct an out of phase recording.

Reverse effect is used to play a part of the track backwards.

  • 7 WEBGRAPHY:

http://help.adobe.com/es_ES/Soundbooth/2.0/WS24B280C0-D791-403e-BCF6-2F89FA925000a.html
http://help.adobe.com/es_ES/Soundbooth/2.0/WS54A347D7-5B5E-4c92-B5BD-98BC29C6E8FFa.html
http://help.adobe.com/es_ES/Soundbooth/2.0/WS31A95313-F021-4d7e-B9A6-21EB6BE70AD3a.html
http://www.adobepress.com/articles/article.asp?p=2171314&seqNum=2
http://blog.vtc.com/adobe-audition-cs6-how-to-increase-the-audio-gain-without-destroying-the-background-sound/
http://www.offbeatband.com/2009/08/the-difference-between-gain-volume-level-and-loudness/
http://helpx.adobe.com/audition/using/automating-mixes-envelopes1.html
http://helpx.adobe.com/audition/using/inverting-reversing-silencing-audio.html
http://www.adobepress.com/articles/article.asp?p=2093891&seqNum=13

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