audio tricks and tips

7/27/2019 Audio Tricks and Tips

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TIPS AND TRICKS FOR AUDIO STORYTELLINGAND AUDACIY OOLS

Common Challenges in Audio Gathering

Pops and Clicks

Sometimes audio recordings contain pops or clicks caused by a too‐hard “p”, “t”, or “k” sound, by a little toomuch saliva as a word is said, or by the microphone recording a sound incorrectly. o avoid these sounds,hold the microphone 6-9 inches away rom the subject matter as the speak. I the sounds still exists, or atruly proessional story, we may want to get rid o any major instances o these pops and clicks in Audacity.

Solutions• Find a clean place to delect the section• Click “Removal”• Amplication

“Um,” “You Know,” Pauses, and Other Junk

Let’s ace it. We don’t always articulate the way we’d like, especially when we’re not using a script. Te resultcan make the audio less than desireable and more likely to lose the audience. We may want to edit outwords, phrases, or ller words such as “um” or “er” or “like”, pauses, or non‐constant background soundsthat are distracting. However, editing can cause its own problems; or instance, the editing can introducepops and clicks. Use the previous solutions listed i this comes up.

Solutions• Find Zero Crossings beore deleting selection• Amplication

Common Sense Tips Go a Long Way!

Audio gathering for Interviews

Hold the microphone a good distance away from the subject matter

Record interviews in quiet rooms

Ask open ended questions not yes or no questions. Examples:

• Describe to me...

• How did that make you feel?

Gathering ambient or natural sounds

Always listen with headphones

Watch your audio levels for peaking

Listen for background noises that you may not want



Ambient Noise

Recordings intended or audio storytelling will contain background noise unless they are recorded in aroom that’s empty or quiet. Even when care is taken to eliminate voices, music, rustling o papers, andother easily noticed background noise, ambient noise will likely come rom an air conditioner, a computeran, or other source o constant, low‐volume noise. No normal room is ever truly silent.

Solutions• Noise Reduction• ry to nd a quiet place and ask subject i you can turn o noisy machines

Differences in Sound from Changes in Location, Equipment, or Subject

Each recording room or other recording location will likely sound a bit dierent rom others because o dierences in how sound reverberates in the space, and any change in recording equipment may causesounds to be picked up dierently. As a result, audio stories recorded in multiple locations or with multipletypes o recorders may exhibit some inconsistency in ambient sound and in volume. In addition, certainspeakers talk louder than others, and this variable can lead to dierences in recording volume when a pod-cast contains multiple participants.

Solutions• Normalization• Amplication

Multiple Recordings and/or Music Files to Interweave Together

Maybe your audio story is done with multiple character’s voices and each subject recorded his or her partseparately rom the others. Maybe you just want to use ambient or natural sound les, and you want to

control the ading or volume o these sounds in relation to other voices. You can ofen imagine complexuses o audio, and implementing what you imagine can be a challenge.

Solutions• ime Shif tool• Fade In / Fade Out eects• Envelope tool• Splitting tracks• Quick Mix• Generating silence



Solutions

Zero Crossings

Sounds are made up o waves, and every sound le is represented in the computer as a waveorm. When aportion o a sound is selected with the mouse, the beginning and end o the selection don’t always (and in

act, usually won’t) line up with a point where this wave crosses the horizontal midline dividing the crestsand troughs. Tus, a selection (very zoomed in) might look like this:

When the selection is deleted, the resulting waveorm thus has an irregular drop rom the crest on the lefto the trough on the right (or vice versa), like this:

When the sound is played, this irregular drop is sometimes heard as a pop or click. A pop or click can alsooccur when an eect is applied to the selection, when the selection is cut and pasted, when the selectionis replaced by silence, and so on. Fortunately, there is an easy solution. Whenever a piece of a waveformis selected, choose “Find Zero Crossings” from the Edit menu in Audacity before taking any actionon the selection. Tis will move the selection both right and lef to the nearest point where the waveormcrosses the zero line, like this:

Ten, when the selection is deleted (or example), the irregular drop seen above is omitted, as shown be-low:



Click Removal

Audacity also provides a simple, rst‐pass method to remove clicks and pops rom audio les. Select“Click Removal” rom the Eect menu in Audacity. Select the desired threshold and maximum spikewidth as described on the dialog box, and the click the “Remove Clicks” button. Keep in mind that

the greater the sensitivity you select, the better the program will remove pops and clicks; however,the distortion o the desired audio will be greater, as well. Te “Preview” button on the Click and PopRemoval dialog box may help you to nd an acceptable level o sensitivity or the particular le youare working with, but sometimes determining the level is a matter o trial and error, requiring mul-tiple “Undo” operations. Since each le may require a slightly dierent setting or optimal results, i your project contains multiple les, make sure that you do this procedure or only one track or le ata time.

Noise Reduction

Noise reduction works by reducing or eliminating sounds that match requencies dened in asample o what silence (or only constant ambient noise) sounds like in the particular le. Desirablesounds in these requencies will also be reduced or eliminated, so if noise reduction is overdone,the audio may sound tinny, robotic, or otherwise distorted (kind o like talking into a an). Also,noise reduction is primarily designed to remove constant sounds, such as the sound coming roman air conditioner or computer an; it is ar less eective at removing sounds such as rustling papers,background voices, etc.

Tere are two steps to using noise reduction. First, select a ew seconds o the le in which thereis nothing but the ambient noise in the room (computer ans or whatever). Ten, choose “NoiseRemoval” rom the Eect menu in Audacity, and click the “Get Noise Prole” button on the dialog

box. Next, select the les, or section o a le, to which you want to apply noise reduction, and ndthe zero crossings or the selection (as described above, in “Zero Crossings”). Finally, choose “NoiseRemoval” rom the Eect menu in Audacity again, select how much noise reduction to apply withthe slider on the dialog box, and click the “Remove Noise” button. As with Click Removal, the “Pre- view” button on the dialog box may help you identiy a proper level o noise reduction to use on theparticular le, but sometimes identiying the proper level is a matter o trial and error. Perorm noisereduction on only one track or le at a time.

NormalizationNormalization is a way to apply a consistent volume level across les. It ensures that the waveorm o the normalized le is centered on the zero line, and that the maximum (volume o the le is ‐3 dB.It is useful to apply normalization to all of your tracks before beginning to mix your podcast. onormalize a track, select the entire track and choose “Normalize” rom the Eect menu in Audacity.Make sure both check boxes on the dialog box are checked, and click the “OK” button.



Another tool that is useul in normalization is dynamic range compression (see “Compressor” under theEect menu in Audacity). Dynamic range compression reduces the amount o volume dierence be-tween the loudest and quietest points in the selection, preventing the large dierences illustrated below:

AmplifcationTe Ampliy eect can be used to increase or reduce the volume o the selected track or section o atrack. Amplication can be used to achieve a more consistent volume level, to reduce overly emphasizedsounds (or example, P, , S) that cause a spike in volume or undesired sounds that can’t be completely removed. Obviously, its primary purpose is to increase or reduce the volume o any recording, even aconsistent recordings, to desired levels.o increase or reduce volume, select the desired track or section o track, nd the zero crossings or theselection, and then choose “Ampliy” rom the Eects menu in Audacity. ype in the decibels by whichyou want to increase (positive number) or decrease (negative number) the volume o the selection. Tisis the amount by which, not to which, the selection volume will be adjusted. Increments o 3 decibelswork well as a starting point or experimentation. Make sure that the “Allow Clipping” check box is

NO checked. Tis prevents the selection rom being amplied so high that the top o any piece o thewaveorm is chopped o, which would lead to high distortion. Ten click the “OK” button.Amplication amplies all the sound in the selection, including background noise, and can lead to somedistortion. Also, when reducing volume, bear in mind that amplication cannot undo the distortingeects o any clipping that happened at the time o recording because o incorrect microphone gain, somake sure that microphone gain is not set too high. As with all o these eects, use amplication judi-ciously. Frequently use the Preview button on the dialog box, plus a healthy dose o trial‐and‐error, tond the optimum level o amplication.

Time Shift Tool

Te ime Shif tool allows you to drag the contents o a track to any point in time on the project time-line. Tis tool is ound in the tool palette to the lef o the playback controls and looks like this:

Click on the ime Shif tool, then click and drag the desired track to the proper location on the timeline.



Fade In / Fade OutYou may want to ade in or out certain tracks in your podcast, particularly i you are using stingers ormusic to signal the beginning and end o portions o the podcast. o use Fade In / Fade Out, selectthe length o the track over which you want the ading to occur. Find the zero crossings. Ten, selecteither “Fade In” or “Fade Out” rom the Eects menu in Audacity, which will result in the volume o

the selection ading to or rom complete silence. o ade a track to or rom a lower volume, use theEnvelope tool.

Envelope ToolTe Envelope tool is used to increase or decrease the volume o a track gradually (unlike the Ampli-y eect) and without going to or rom zero volume (unlike Fade In and Fade Out). One example o where the Envelope tool might be used is to have music playing and then to ade that music to a lower volume or ew seconds as a speaker begins to speak, then keep the volume lower but still audiblewhile the speaker is speaking, and then gradually bring the volume o the music back to its originallevel as the speaker is ending her remarks.

Te Envelope tool is ound in the tool palette to the lef o the playback controls and looks like this:

Afer clicking the Envelope tool, click the desired track at the point where you want the volume changeto begin. Tere will be a small handle on the top and bottom edges o the track at this point. Hold themouse button down and drag up or down while over one o these handles to increase or reduce the volume o the track (indicated by the amplitude, or height, o the waveorm). Adding multiple suchpoints on the track allows or complex shaping o the volume. For example ading rom ull volume toa lower volume then back to ull volume again requires our such points or handles. Illustrated below

are two o those handles, used to lower the volume o music as a speaker begins to talk.

Splitting TracksSometimes you may want to take what is on one track and split it into multiple tracks, to allow thepieces to be moved independently on the timeline with the ime Shif tool. One example might be arecording o a story using multiple voices, where each actor recorded his or her parts separately romthe others, and these parts are imported as one track but must be broken up and interwoven withthe parts o other actors. o split a track, select the section o the track that you want to split out andnd the zero crossings. Ten choose “Split” rom the Edit menu. Te selected section o track will bemoved to a new track, and replaced by silence in the original track.



Quick MixQuick Mix is the opposite o splitting a track. It allows you to combine the contents o multiple tracks intoone track. For example, the illustration below shows three tracks:

And the ollowing illustration shows the rst and third tracks combined with QuickMix:

Notice that the position o each track on the timeline is maintained in the combined track. I necessary,silence is generated between the clips on the combined track.

It is possible to combine tracks that overlap each other on the timeline, but once this is done, the overlap-ping sections will NOT be able to be separated, as they will become part of a combined waveform. Do thisonly with extreme caution.

Quick Mix is a great way to keep the number o tracks you are working with manageable by combiningtracks once the need or them to be separate has passed. o use Quick Mix, select the desired tracks by clicking on the track inormation area to the lef o each track (indicated by the red arrow in the illustrationabove). Hold down the Shif key while selecting the second and subsequent tracks. Ten choose “Quick

Mix” rom the Project menu.

Generating SilenceOne way to move sections o audio on a track urther apart is by splitting the track into two, and then usingthe ime Shif tool. Another is to generate silence to lengthen the space between the two sections. o gen-erate silence, put the cursor on the timeline at the point where you want the silence to appear, then choose“Silence” rom the Generate menu in Audacity. ype in the length o the silence you want to generate, andclick the “Generate Silence” button.



Proactively Addressing Challenges

Because most o the above eects, such as amplication and noise reduction, have both limits on what they can achieve and possible undesirable side eects, it is important to proactively address challengesyou can anticipate. For example, use a pop lter or windscreen between your mouth and the microphone toreduce the incidence o pops and clicks. Pop lters are inexpensive, but i needed, a pop lter can even be

constructed rom a bent hanger and a piece o nylon stockings.

Make sure that gains on microphones, and distances between microphones and the recording subject, are setproperly so as to minimize the need or amplication. As much as possible, eliminate undesirable backgroundnoise, especially noise such as other voices, paper rustling, etc., rom the recording environment. Use a scriptwhen possible to avoid undesired pauses and meaningless ller words like “um,” “er,” and “like.” Completely nish reading rom one page o the script beore turning the page and beginning to read again. Tis makesthe rustling o the pages much easier to edit out than i pages are rustling while you are still talking.

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