How to Clean Audio with Audacity: The Complete Guide 2025

In today’s content-driven world, audio quality can make or break your project. Whether you’re producing a podcast, creating educational materials, recording music, or preserving important moments, poor audio quality immediately diminishes the professionalism and impact of your work. Research shows that listeners are more likely to distrust content and abandon recordings when audio quality is subpar.

Fortunately, Audacity—a free, open-source audio editor—provides powerful tools to transform problematic recordings into clear, professional-sounding audio. This comprehensive guide will walk you through proven techniques to clean up even the most challenging audio issues, from persistent background noise to pops, clicks, and uneven volume levels.

Understanding Audacity

Audacity has earned its reputation as the world’s most popular free audio editor for good reason. This powerful, cross-platform application offers professional-grade tools that would otherwise cost hundreds of dollars in commercial software.

Key Features and Recent Updates

The latest versions (Audacity 3.6 and 3.7) have introduced several improvements specifically for audio cleaning:

• Master Effects Channel: Apply effects to entire projects simultaneously
• Enhanced Compressor and Limiter: Greater control over audio dynamics
• Improved Interface: More intuitive access to essential tools
• Performance Enhancements: Faster processing for larger files

Essential Audio Cleaning Tools

Audacity offers a comprehensive toolkit for audio restoration:

• Noise Reduction: Remove constant background noise like fans, hums, or room tone
• Click Removal: Eliminate pops, clicks, and digital artifacts
• Notch Filtering: Target specific frequency noises like electrical hums
• Truncate Silence: Intelligently manage silent passages
• Equalization: Fine-tune frequency balance for optimal clarity
• Compression/Limiting: Control dynamic range for consistent volume
• Batch Processing: Apply identical effects to multiple files simultaneously

Before You Start: Best Practices for Recording

While Audacity can work wonders on problematic audio, starting with the best possible recording will always yield superior results. Consider these pre-recording best practices:

Equipment Recommendations

• Microphone Selection: Even affordable condenser microphones like the Behringer B-1 ($75) or Audio-Technica AT2010 ($95) dramatically outperform built-in computer or smartphone mics
• Pop Filter: An inexpensive pop filter ($10-20) significantly reduces plosives (harsh “p” and “b” sounds)
• Headphones: Closed-back monitoring headphones allow you to catch issues during recording
• Stable Mounting: Use a microphone stand or boom arm to prevent handling noise

Environment Setup

• Room Selection: Choose a quiet room with minimal echo—walk-in closets with hanging clothes make excellent improvised recording booths
• Eliminate Noise Sources: Turn off fans, air conditioners, refrigerators, and other sources of background noise
• Microphone Placement: Position your microphone 6-12 inches away for voice recording, using a slight off-axis angle to reduce plosives
• Capture Room Tone: Always record 5-10 seconds of ambient noise without speaking to use as a noise profile for later cleanup

Basic Cleanup: Noise Reduction

Noise reduction is typically the first and most important step in cleaning up audio. Audacity’s noise reduction tool works by analyzing a sample of the background noise in your recording, then algorithmically removing similar sounds throughout the entire track.

Step-by-Step Noise Reduction Process:

1. Select a noise sample:
2. Find a section of your recording that contains only background noise
3. Ideally, use 2-3 seconds of continuous noise without any speech or desired sounds
4. This “noise profile” is why recording room tone before speaking is so valuable
5. Get the noise profile:
6. Go to Effect > Noise Removal and Repair > Noise Reduction
7. Click “Get Noise Profile”
8. Audacity will analyze the selected section (the dialog will close automatically)
9. Apply noise reduction to the entire track:
10. Select the entire track (Ctrl+A or Command+A)
11. Go to Effect > Noise Removal and Repair > Noise Reduction again
12. Adjust the parameters:
    • Noise reduction: 12 dB is a good starting point (6-18 dB range is typical)
    • Sensitivity: 6.00 strikes a good balance (higher values remove more noise but risk artifacts)
    • Frequency smoothing: 3 bands works for most recordings (higher values sound more natural but less noise is removed)
13. Preview before applying:
14. Use the “Preview” button to hear how your settings will affect the audio
15. The “Residue” toggle lets you hear what will be removed rather than what will remain
16. If you hear desired audio in the residue, reduce your settings
17. If you still hear significant noise in the preview, increase your settings
18. Apply the effect: When satisfied with your settings, click “OK”

Common Mistakes to Avoid:

• Over-processing: Excessive noise reduction creates unnatural “underwater” or “robotic” artifacts
• Using an inappropriate noise profile: Your noise sample must accurately represent the background noise
• Applying noise reduction multiple times: This compounds artifacts; adjust settings instead of reapplying
• One-size-fits-all approach: Different sections of your recording may need different noise reduction settings

Advanced Noise Removal Techniques

For more challenging audio problems, Audacity offers specialized tools that can be used alongside basic noise reduction.

Using Noise Gate

The Noise Gate attenuates sounds below a certain threshold, making it ideal for reducing background noise during pauses in speech without affecting the primary audio.

1. Select a part of the audio containing only background noise
2. Go to Effect > Noise Gate
3. Click “Select Function: Analyse Noise Level” and press OK
4. Note the recommended threshold level (typically between -30dB and -45dB)
5. Select the entire audio track
6. Open Noise Gate again, set it to “Select Function: Gate,” and enter the threshold
7. Configure additional parameters:
8. Gate frequencies above: 0 Hz (to affect all frequencies)
9. Gate frequencies below: 20000 Hz (to affect all frequencies)
10. Attack/decay time: 100 ms (adjust for natural-sounding transitions)
11. Level reduction: -24 dB (how much to reduce noise below the threshold)

Applying Notch Filter

The Notch Filter removes noise at specific frequencies, perfect for eliminating electrical hums, whines, or electronic interference.

1. Select the audio you want to process
2. Go to Effect > Notch Filter
3. Enter the frequency you want to reduce:
4. 50Hz for European power line hum
5. 60Hz for North American power line hum
6. Use Analyze > Plot Spectrum to identify other problematic frequencies
7. Set the Q-value (higher values create a narrower, more targeted filter)
8. Click OK to apply

Pro Tip: Sounds often have harmonics at multiples of the base frequency. For a 60Hz hum, you may need to apply additional notch filters at 120Hz, 180Hz, etc.

Using Master Effects (Audacity 3.6+)

Newer versions of Audacity allow you to apply effects to the entire project through the master channel:

1. Click the dropdown menu in the master channel section (top of the track panel)
2. Select “Add Effect” and choose your desired effect
3. Configure the effect parameters
4. The effect will apply to all audio in real-time, allowing you to adjust parameters while listening

Removing Clicks, Pops, and Plosives

Clicks and pops are brief, sharp noises that often occur from editing cuts, microphone bumps, or mouth sounds. Here’s how to address them:

Using the Click Removal Tool

1. Select the audio containing clicks or pops
2. Go to Effect > Noise Removal and Repair > Click Removal
3. Adjust the threshold (higher values remove more clicks)
4. Set the spike width (how many milliseconds wide detected clicks can be)
5. Use Preview to test settings before applying

For stubborn clicks that the automatic tool misses:

1. Zoom in closely on the problematic click (it will appear as a sharp spike)
2. Select just the click (typically 5-20 milliseconds)
3. Go to Effect > Noise Removal and Repair > Repair
4. This specialized tool reconstructs audio by interpolating from surrounding content

Dealing with Plosives

For plosive sounds (those harsh “p” and “b” sounds that cause microphone overload):

1. Identify the plosive in the waveform (look for large, sudden spikes)
2. Apply a high-pass filter to the affected section:
3. Select just the plosive section
4. Go to Effect > Filter Curve EQ
5. Create a curve that reduces frequencies below 100-120Hz
6. This preserves speech intelligibility while removing the low-frequency blast

Silence Management

Strategic silence handling is crucial for professional-sounding audio. Long silences make recordings feel awkward, while completely removing all pauses makes speech sound unnatural and rushed.

Using Truncate Silence

Audacity’s Truncate Silence feature intelligently compresses silent passages:

1. Select the audio you want to process
2. Go to Effect > Special > Truncate Silence
3. Configure the parameters:
4. Detection level: -20dB works well for voice recordings (sounds quieter than this are considered silence)
5. Duration: 0.5 seconds (how long a sound must be below threshold to be detected as silence)
6. Truncation: 0.5-1.0 second (how long silences will be after processing)
7. Click OK to apply

Best Practice: Use Truncate Silence after applying noise reduction, as cleaner audio allows for more accurate silence detection.

Enhancing Audio Quality

After removing unwanted elements, you can further enhance your audio through equalization and dynamic processing.

Using Equalization

Equalization adjusts the balance of frequencies in your audio, enhancing clarity and presence:

1. Select your audio
2. Go to Effect > Volume and Compression > Equalization
3. Choose a preset (like “Voice Enhancement”) or draw your own curve
4. For voice recordings, consider:
5. High-pass filter at 80-100Hz to eliminate rumble and room resonance
6. Slight boost (2-3dB) around 2-3kHz for improved clarity and articulation
7. Gentle reduction around 200-300Hz to remove muddiness
8. Optional slight boost around 5-8kHz for presence and “sparkle”
9. Use Preview to test your adjustments before applying

Applying Compression and Limiting

The improved compressor and limiter in Audacity 3.6+ offer powerful tools for controlling dynamic range:

1. Compression makes quiet parts louder and loud parts quieter for more consistent volume:
2. Select your audio
3. Go to Effect > Volume and Compression > Compressor
4. Set threshold to -18dB (adjust based on your recording)
5. Set ratio between 2:1 and 4:1 for voice (2:1 is more natural, 4:1 more consistent)
6. Set attack time to 10-20ms (faster catches more transients)
7. Set release time to 100-200ms (for natural-sounding results)
8. Enable “Make-up gain” to restore overall volume
9. Limiting prevents any peaks from exceeding a specified level:
10. After compression, apply Effect > Volume and Compression > Limiter
11. Set the limit to -0.5dB to prevent digital clipping
12. Use “Hard Limit” mode for more aggressive control
13. Set “Hold” to 10ms and “Release” to 100ms for voice

Normalizing Audio Levels

Normalization ensures your audio utilizes the optimal volume range:

1. Select your audio
2. Go to Effect > Volume and Compression > Normalize
3. Check “Remove DC offset” to center the waveform vertically
4. Set peak amplitude to -1.0dB (this prevents potential clipping)
5. Click OK to apply

Workflow Optimization: Batch Processing

For podcasters, educators, and content creators working with multiple files, Audacity’s batch processing can save hours of repetitive work:

1. Go to Tools > Apply Chain
2. Click “Manage Chains” and then “Add” to create a new chain
3. Add your standard cleanup effects in sequence (e.g., Noise Reduction, Click Removal, EQ, Compression, Normalize)
4. Save the chain with a descriptive name (e.g., “Podcast Voice Cleanup”)
5. To process multiple files:
6. Select the chain
7. Click “Apply to Files”
8. Choose your input directory (where your raw files are located)
9. Choose your output directory and file format
10. Click “Apply” to process all files at once

Exporting and Finalizing

Once your audio is clean and enhanced, it’s time to export:

1. Go to File > Export > Export as [desired format]
2. Choose the appropriate file format:
3. WAV for highest quality (lossless but large file size)
4. MP3 for good quality with smaller file size
5. FLAC for lossless compression (smaller than WAV but still lossless)
6. OGG for high quality with very small file size
7. Configure format-specific options:
8. MP3: 128-320 kbps bit rate (higher = better quality but larger files)
9. WAV: 16-bit or 24-bit depth, 44.1kHz or 48kHz sample rate
10. Add metadata if desired (title, artist, album, year, etc.)
11. Choose your destination and click “Save”

Recommended Export Settings for Different Purposes:

• Podcasts: MP3, 128-192 kbps, mono or stereo
• Music: WAV (for archiving) or MP3 320 kbps (for distribution)
• Voice recordings: MP3 96-128 kbps mono is often sufficient
• Streaming: MP3 192 kbps or higher recommended
• Professional production: WAV 24-bit/48kHz for maximum quality

Troubleshooting Common Issues

Even with careful technique, you may encounter challenges during the audio cleaning process. Here are solutions to common issues:

Artifacts After Noise Reduction

If you hear “underwater” sounds, “musical” artifacts, or robotic voice quality: – Reduce the “Noise reduction” value (try 6-9dB instead of 12dB) – Increase “Frequency smoothing” bands (try 5-6 instead of 3) – Ensure your noise profile comes from a clean, representative section – Consider using multiple passes with gentler settings rather than one aggressive pass – Try the Noise Gate as an alternative approach

Distortion Problems

If your audio sounds distorted: – Check if any part of the waveform is clipped (appears as flat horizontal lines at the top/bottom) – Apply the Limiter effect to prevent peaks from exceeding -0.5dB – Use the Repair effect on small sections of distorted audio – Check if equalization is creating peaks that cause clipping – Ensure compression settings aren’t too aggressive (ratio above 6:1)

Inconsistent Audio Levels

If volume levels vary too much even after compression: – Apply more aggressive compression (higher ratio, lower threshold) – Use the Amplify effect to bring up specific quieter sections – Consider splitting the recording into sections for more targeted processing – Apply the Envelope Tool to manually adjust volume variations – Use the Auto Duck effect if background music is competing with voice

Conclusion

With Audacity’s powerful toolkit, you can transform even the most problematic recordings into clear, professional-sounding audio. The key is a methodical approach: start with noise reduction, address specific issues like clicks and pops, manage silence, enhance overall sound quality, and finally export with appropriate settings.

Remember that audio cleaning is both science and art—these techniques provide a solid foundation, but don’t be afraid to experiment and develop your own workflow. With practice, you’ll develop an ear for what works best for different recording types and environments.

By implementing these techniques, you’ll produce cleaner, more professional audio that keeps your audience engaged and focused on your content rather than distracted by poor sound quality. Whether you’re a podcaster, educator, musician, or content creator, mastering Audacity’s audio cleanup tools will significantly elevate the quality and impact of your work.

References and Resources

• Official Audacity Documentation
• Audacity Forum
• Audacity Wiki
• Recommended Plugins for Audacity
• Audacity Manual: Noise Reduction
• Audacity Manual: Compressor