How to Work with Audio Effects on Your iPad or iPhone

By Ryan C. Williams, Mike Levine

Audio effects on your iPad or iPhone let you change your music file a bit and give it a little extra personality. Although Auria is used to demonstrate audio editing here, you should definitely feel free to download some of the free audio editors and review these kinds of effects before you buy anything. Everything that is reviewed here either comes standard or via in-app purchase.

Adjusting volume level

Suppose you’ve got a quiet section of audio, and you need to make it louder. Just load it into the editor and crank up the volume! You could do this to the entire file, or you could just select a section of the file and boost the volume to that section.

Adjusting volume level at this level involves lowering or raising the volume on a specific section of audio, not the overall track or the recording in general. This ability lets you compensate for lower recordings or take the edge off of a particularly “hot” or loud recording.

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In Auria, you can see different handles on an audio clip at the top of the clip and in the corners. The volume handle appears in the middle of the clip. Tap that handle and drag up and down to get the volume you’re looking for.

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Some audio editors also provide a volume or gain knob for a clip, but the iPhone and iPad allow you to drag the controls on the clip in a very precise and interactive way.

Normalizing audio

When you normalize an audio file, you take the highest peak of that audio to a specified level. The rest of that audio file also increases by that level as well.

Although most normalization functions allow you to bring the peak of the audio file up to 0 dB, this use of normalization isn’t usually a good idea, especially if you aren’t dealing with your final track.

Normalizing isn’t a control you set by dragging controls over a clip. The process analyzes the overall audio clip and adjusts the volume accordingly. Select the clip and tap Process to see the list of available processing effects.

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Select Normalize to see this function.

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The Normalize process in Auria allows you to adjust the volume level based on the previously mentioned peak value (the loudest peak of the entire audio file) or the RMS value (an involved mathematical formula that basically determines the average volume level of the audio clip). Suppose that you want to normalize this clip to –13 dB based on the peak value. Adjust the Level knob to as close to –13 dB as you can get and leave the Mode switch on Peak.

The Release knob affects the Limit button on the Clipping Mode switch, where it determines how the limiter effect kicks in. The limiter prevents audio from going over a certain dB level, and the knob determines when the effects let go. You can leave it at a short period of time to affect only the peaks of the audio, or you can set it longer to smooth out more of the clip.

The Saturate option offers a distortion-type effect to take place when the audio clips, and the Ignore option lets it all run wild. Leave the settings as is here and tap OK. You see the waveform increase in size, indicating a louder volume.

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Fading in and out

If you’ve ever heard the volume increase at the beginning of a track or decrease at the end of a track, you’ve heard a fade in or a fade out. A fade refers to the gradual increase or decrease in volume, either quickly or slowly.

Check out this keyboard track. It’s going to be faded in.

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In this example, the upper-left corner of the screen is dragged in toward the middle of the clip to begin the fade in. Notice how the waveform became smaller at the beginning of the clip and becomes larger as the clip progresses.

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Depending on the audio editor, you may encounter linear fades, exponential fades, logarithmic fades, equal power fades, and more. These terms describe exactly how the audio fade occurs, and you can see exactly how the fades look in the audio file.

Next, fade out the clip by dragging the top-right corner down.

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Reversing audio

Typing words backwards just gets you a jumbled mess, but reversing audio gives you a cool effect. Again, you can apply this effect to the entire track or just a section of your audio.

In this case, the hi-hat track in the recording was reversed.

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After selecting the clip, tap Process and select Reverse. Notice the change in the waveform.

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Trimming audio

Suppose you have a track that includes a bunch of noise or silence at the beginning or end of the track. Most audio editors let you move the beginning or end of the track to start at a different point in the clip instead of the very beginning. This process alters the clip quickly and doesn’t erase any audio in the process.

If you want to move the beginning of a clip, select the bottom-left corner of the clip and move it to the point where you want the audio clip to begin.

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You can do the same to the end of the clip as well, if you wish.

Adding silence

If you want to insert a bit of silence into a clip, you can select that portion of the clip and make it quiet. Audio editors can easily remove any waveform and insert the silence you require.

Double-tap the clip and move the selection until you get the part of the clip you want.

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After you tap Process and select Silence, the clip looks like this.

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Note that this process doesn’t just remove the primary part of the audio — it also takes out the background noise.