GarageBand Noise Reduction Plugin: Remove Hiss In Minutes

You captured what sounded like a clear voice during last night’s investigation, but when you play it back, all you hear is hiss, hum, and static burying the evidence. Whether you’re cleaning up EVP recordings from a paranormal investigation or editing audio from any field session, a garageband noise reduction plugin can strip away that unwanted noise without expensive software.

GarageBand ships free on every Mac and iPad, and it includes built-in tools like the Noise Gate that most users never touch. There are also third-party plugins, such as AUSoundIsolation, that plug right into GarageBand and give you even more control over what stays and what goes.

At Haunt Gears, we test and review the equipment investigators actually use in the field, and audio processing is a critical part of any serious investigation workflow. This guide walks you step by step through removing background noise, hiss, and interference from your GarageBand recordings, no audio engineering degree required. By the end, you’ll have a repeatable process that turns muddy captures into clear, reviewable audio in minutes.

What noise you can fix in GarageBand

GarageBand is not a professional audio restoration suite, but it handles the most common types of field recording noise better than most investigators expect. Before you reach for a paid plugin or a separate app, it helps to understand which problems fall within GarageBand’s range and which ones fall outside it. Understanding that difference saves you time and sets realistic expectations for what your garageband noise reduction plugin workflow can actually deliver on a real recording.

Not every noise problem is fixable in post-production. If a sound overlaps your signal at the exact same frequency, no plugin can separate them without damaging the original audio.

Noise that GarageBand’s built-in tools handle well

The built-in tools in GarageBand target steady-state and low-level noise that sits underneath your main audio. These are the noise types you’ll encounter most often in paranormal investigation recordings, where long silences between potential EVP responses let background interference build up on the track. The key trait they share is consistency: the noise stays roughly the same volume and pitch throughout the recording, which makes it predictable and therefore removable.

Here is a breakdown of what each noise type sounds like and which tool addresses it:

Each of these noise types responds to a targeted approach, which is why this guide covers them in a specific order rather than giving you a single dial to turn up. Using the right tool on the right problem keeps your signal intact while the unwanted layer gets stripped away.

Noise that will resist standard tools

Some problems sit beyond what any built-in GarageBand effect can fully resolve. Clipping happens when audio peaks hit 0dB and the waveform gets cut off at the top and bottom. That distortion is baked into the digital file at the moment of recording, and no plugin can reconstruct the missing data after the fact. The same limitation applies to noise that shares the exact same frequency range as your signal, such as two people talking at the same time or a television playing in the background during an EVP session.

Intermittent noise also presents a real challenge. Sounds like a sudden static burst, a door creak mid-capture, or a car passing outside are difficult to remove without cutting the surrounding audio manually. GarageBand does not include a spectral repair tool the way dedicated restoration apps do, so these one-off events require hands-on editing rather than automated plugin processing. Recognizing these limits before you start helps you decide when to invest time cleaning a recording and when to re-record the session entirely. Going into the cleanup process with that clarity keeps your workflow efficient and your evidence credible.

Step 1. Diagnose your noise and set a clean baseline

Before you open a single garageband noise reduction plugin, you need to know exactly what you’re dealing with. Skipping this step leads to over-processing, which strips useful detail from your signal along with the noise. Take two to three minutes to listen to the raw recording from start to finish through headphones rather than speakers, so you can catch subtle problems that small monitors miss. Every decision you make in the following steps will only be as good as the diagnosis you do right here.

Listen on headphones and write down what you hear

Closed-back headphones give you the most accurate picture of what’s on the track. As you listen, write down timestamps where the noise is loudest and note whether it sounds steady, like a hiss or hum, or intermittent, like a pop or creak. Steady noise responds well to automated plugin processing, while intermittent sounds often need manual cuts using the scissor tool in GarageBand’s timeline. Knowing which category your problem falls into before you start will save you from applying the wrong tool and making the recording worse.

If the noise changes pitch or volume throughout the recording, that variation signals something more complex than standard background hiss, and a single plugin pass likely will not be enough.

Find and mark your noise floor sample

Find a section of your recording where no voice, intended sound, or signal is present, just the background noise running on its own. That clip could be the first few seconds before an EVP session started, or a quiet gap between questions. This becomes your noise reference: a snapshot of the exact interference pattern you need to remove.

Split that section out using Command+T at both ends in GarageBand’s timeline. Keep it on the track but mute your main audio region while you study it. Play it back three or four times and confirm it represents the consistent background character of the full recording rather than a spike or a one-time event. Once you have that reference locked in, every plugin decision in the steps ahead will be anchored to a real sample instead of a guess.

Step 2. Use GarageBand Noise Gate the right way

The Noise Gate is the first built-in garageband noise reduction plugin you should reach for, because it targets silence between audio events rather than the signal itself. It works by setting a volume threshold: any audio that falls below that threshold gets silenced automatically. For paranormal recordings, this means the low-level hiss and hum that fill the gaps between potential EVP responses gets cut without touching the moments where something is actually happening on the track.

How to open and load the Noise Gate

Click on the track you want to process, then open Smart Controls at the bottom of the screen by pressing B on your keyboard. Click the plug icon on the left side to switch to the Plugin view. From there, click one of the empty plugin slots, hover over Dynamics, and select Noise Gate from the submenu. GarageBand loads it directly into the channel strip and the plugin window opens immediately. You can also access it through the Audio FX section in the channel strip on the left panel if Smart Controls are already visible.

The Noise Gate processes audio in real time, so you can adjust settings while the track plays back and hear the result immediately without committing to a bounce.

Setting the threshold and release correctly

The Threshold knob is the most important control in the Noise Gate. Start by playing your track and slowly dragging the threshold up from its lowest position until the background hiss disappears during the quiet sections. Stop the moment you notice any wanted audio getting cut, then back the threshold off slightly from that point. A common starting range for field recordings with moderate hiss is between -50dB and -40dB, but your actual noise floor sample from Step 1 tells you the right ballpark for your specific file.

The Release knob controls how quickly the gate closes after audio drops below the threshold. Set it too fast and you’ll hear an unnatural click at the end of each audio event. A release time of 200 to 400 milliseconds works well for voice recordings, giving the gate enough time to close smoothly without letting noise bleed back in between captures.

Step 3. Use AUSoundIsolation for steady background noise

Where the Noise Gate handles the silence between audio events, AUSoundIsolation targets the consistent hiss and rumble that runs underneath your entire recording, even when your main signal is present. This plugin ships with macOS as part of Apple’s Core Audio framework, which means you already have it installed on your Mac without downloading anything extra. It analyzes the noise character across the full track and suppresses it in a continuous pass, making it the most capable garageband noise reduction plugin available inside GarageBand for free.

How to load AUSoundIsolation into GarageBand

Loading AUSoundIsolation follows the same path as any other plugin in GarageBand. Click your target track, press B to open Smart Controls, then click the plug icon on the left to enter the Plugin view. Click an empty plugin slot, hover over Audio Units, and look for AUSoundIsolation in the list. If it does not appear immediately, select "AU" from the manufacturer or category filter at the top of the menu to narrow the results down.

Work through these steps in order so nothing gets missed:

1. Select the audio track you want to process.
2. Press B to open Smart Controls and switch to the plug icon view.
3. Click an empty slot under the Audio FX section.
4. Navigate to Audio Units > AUSoundIsolation.
5. Double-click the plugin name to open its control window.

AUSoundIsolation performs best on recordings where the background noise stays consistent throughout the file, which makes it the right tool for steady preamp hiss or HVAC hum captured during a long investigation session.

Setting the controls to clean up field recordings

The plugin gives you two primary controls: Noise Reduction and Smoothing. Start the Noise Reduction slider at around 50 and play your recording back in real time. Raise it gradually until the background hiss fades without pulling texture out of your main signal. If you hear a metallic or warbling quality begin to develop in the voice or sound you are trying to preserve, back the slider down by five to ten points until that artifact clears.

Smoothing controls how the plugin transitions between active noise reduction and normal signal processing. A value between 10 and 20 gives you natural-sounding results on voice recordings without creating a noticeable pumping effect on the track. Once you find a combination that works, write down both values so you can apply the same settings to other recordings captured with the same gear under the same conditions.

Step 4. Reduce hiss with EQ and a simple effect chain

EQ works differently than the plugins in the previous steps. Instead of gating silence or analyzing noise patterns, EQ targets the specific frequencies where hiss lives and reduces their volume directly. When you run EQ after the Noise Gate and AUSoundIsolation, you clean up whatever residual high-frequency noise those tools left behind without reprocessing audio that’s already been handled.

Apply a high-pass filter first

The Channel EQ in GarageBand gives you a high-pass filter that removes low-frequency rumble below a set cutoff point. Open it by clicking an empty plugin slot on your track and navigating to EQ > Channel EQ. Enable the high-pass filter on the far left of the EQ display and drag the frequency cutoff to around 80Hz to 100Hz for voice recordings. This cuts the sub-bass rumble from HVAC systems and handling noise without touching the voice range, which typically sits above 150Hz.

Setting the high-pass filter slope to 12dB per octave gives you a firm cutoff that eliminates rumble cleanly without the gradual rolloff that lets low-frequency noise bleed through.

Cut the hiss shelf with a high-frequency reduction

Once the low end is handled, focus on the high-frequency shelf where hiss concentrates. In Channel EQ, enable the high shelf and set its starting frequency to around 8kHz to 10kHz. Apply a reduction of 3 to 6dB and play the recording back. You should hear the hiss drop while the voice or signal retains most of its clarity. Avoid cutting more than 8dB here, because heavy reduction makes voice recordings sound muffled and removes the natural brightness that helps listeners identify speech clearly.

Lock in your effect chain order

Your final effect chain order matters as much as the individual plugin settings. Run your plugins in this sequence to get the cleanest result on every recording:

1. Noise Gate (silences gaps between audio events)
2. AUSoundIsolation (strips steady background hiss and rumble)
3. Channel EQ (targets specific frequency problems)

This order lets each garageband noise reduction plugin do its specific job without undoing the work of the one before it. Once you land on settings that work for your recording setup, save the chain as a GarageBand plugin preset so you can load it instantly on future sessions captured with the same gear.

Next steps

You now have a complete, repeatable workflow for cleaning up field recordings using a garageband noise reduction plugin combination inside GarageBand. The Noise Gate handles the gaps between audio events, AUSoundIsolation strips the steady hiss, and Channel EQ targets any leftover high-frequency noise the other tools miss. Run these three plugins in order every time you bring a new recording into the session, and you will spend less time hunting through static and more time analyzing what actually matters on the track.

Audio quality directly affects the credibility of your evidence, so the gear you record with in the field sets the ceiling for how clean any post-processing can get. If your recorder or microphone is introducing more noise than these tools can handle, that signals a need to upgrade before the next investigation. Browse professional paranormal investigation gear to find tools built for reliable field recording in difficult environments.