To use the Sound Optimizer, open your audio file, remove rumble with Low Cut, quieten the pauses with the Noise Gate and shape the tone with Bass, Mid and Treble. Then even out the volume with the compressor and raise Volume / Gain until the loudness is close to -14 LUFS (about -16 LUFS for podcasts) with peaks at or below -1 dB, and download the result as a WAV file.
In Short
With the free Sound Optimizer you can:
- Reduce rumble, and silence hum and hiss in the pauses of a recording.
- Make a voice sound clearer, warmer and less harsh.
- Make quiet recordings louder without clipping.
- Add fades, change the speed or pitch, and create 8D audio.
- Download a WAV file at the right loudness for Spotify, YouTube or your podcast.
No software and no account are needed, and your files never leave your device.
What Is the Sound Optimizer Tool?
If you have ever recorded a podcast, a voice-over for a video or your own song, you have probably noticed that the raw recording doesn’t sound as polished as professional audio. The voice may be boomy, there may be a hum in the background, some words may be much louder than others, or the whole recording may simply be too quiet.
The Sound Optimizer brings the usual fixes for these problems together on one page. You open your file, move a few sliders while listening to the result, and download the improved version. There is nothing to install, and you don’t need any audio engineering experience.
What You Can Do with the Sound Optimizer
Here is what the tool does, in plain language. Use one feature or all of them, depending on what your recording needs.
Check Your Audio Instantly
As soon as you open a file, the tool shows three numbers: an estimate of the Tempo (BPM), the overall Loudness in LUFS, and the Peak, the loudest point in the file. While the audio plays, the Loudness and Peak meters switch to live values measured after your changes, so you can always see whether you are on target.
Remove Background Noise and Rumble
The Low Cut filter removes deep rumble from traffic or bumps on the desk, and the High Cut filter can soften hiss in phone or video-call recordings. The Noise Gate mutes the hum of a computer fan, an air conditioner or room noise in the pauses between your words.
Make Your Voice Clearer
With the Bass, Mid and Treble sliders you can make a voice warmer, fuller or brighter. Is the recording boomy? Turn the Bass down a little. Does it sound dull? Turn the Treble up a little. The De-Esser softens sharp S and SH sounds that can be unpleasant on headphones.
Make Quiet Audio Louder Without Distortion
Volume / Gain makes the recording louder. To keep it from clipping, the compressor first turns down the loudest moments, like a laugh or a raised voice, so the whole recording sounds more even. If the peaks would still go above 0 dB when you export, the tool lowers the overall level to -1 dB automatically.
Add Fades and Creative Effects
Add a smooth fade-in at the start and a fade-out at the end. For creative projects you can change the Speed or the Pitch; both work like a turntable, so tempo and pitch change together (faster and higher gives the sped-up “nightcore” sound). To change one without the other, use the Pitch & Speed Changer. 8D Audio moves the sound slowly from side to side when you listen on headphones.
Download a File Ready for Any Platform
When you are happy with the sound, choose Stereo or Mono and a Sample Rate: 44.1 kHz for music and podcasts, or 48 kHz for video. The result is downloaded as a 16-bit WAV file, and a line under the button shows the loudness and peak of the exported file.
Please use the tool with audio you own or have permission to use, such as your own recordings, podcasts, voice-overs and royalty-free music. Publishing edited versions of someone else’s songs usually requires permission from the rights holder.
How to Use the Sound Optimizer in 6 Easy Steps
Put on headphones so you can hear every change clearly, then follow these steps.
Step 1: Open Your Audio File
Open the Sound Optimizer and drag your file onto the file box, or click Choose File. MP3, WAV, FLAC and M4A work in all modern browsers; OGG depends on your browser. If you have the original WAV version of your recording, use that for the best quality.
Step 2: Read the Meters
The studio sits right below the file box. Once the file has loaded, you see its waveform, tempo, loudness and peak level. Note the loudness: it tells you how far you are from your target (see the table below).
Step 3: Clean Up the Background
Press Play. If you hear a low rumble, move the Low Cut slider slowly to the right until it disappears; for voices, 80 to 100 Hz works well. Next, play a part where nobody is speaking and raise the Noise Gate until the background goes quiet. If the ends of your words start to disappear, move it back a little. For more detail, read our guide to removing background noise.
Step 4: Make the Sound Clearer
Move the Bass, Mid and Treble sliders in small steps of 1 to 3 dB. Small changes sound natural; big ones rarely do. If S sounds are sharp, raise the De-Esser until they sound smooth. Our guide to bass, mid and treble shows what each slider changes.
Step 5: Set the Right Volume
First set the Compression Ratio to around 3:1 and move the Compressor Threshold to the left until the loudest moments are gently turned down. Then raise Volume / Gain while watching the meters. Stop when the Loudness meter is close to your target and Peak stays at or below -1 dB. If the peak goes too high, lower the threshold a little more before adding volume. Our Spotify mastering guide explains this in more detail.
Step 6: Add Fades and Download
If you like, add a short fade-in and fade-out. Then choose Stereo (music and video) or Mono (a single voice), pick 44.1 kHz for music and podcasts or 48 kHz for video, and click Download Audio (WAV). The file is saved to your device, and the line under the button tells you its final loudness and peak.
How Loud Should Your Audio Be?
Spotify, YouTube and most streaming apps even out the volume of what they play. If your audio is much louder than their target, it is turned down; if it is much quieter, it may sound weak next to other content. Aim for these values:
| Where you will publish | Loudness target | True peak |
|---|---|---|
| Spotify and other music apps | About -14 LUFS | -1 dBTP or lower |
| YouTube and social media videos | About -14 LUFS | -1 dBTP or lower |
| Podcasts (Apple Podcasts and others) | About -16 LUFS | -1 dBTP or lower |
The Spotify and podcast targets come from the platforms themselves: see Spotify’s loudness guidelines and Apple Podcasts audio requirements . YouTube doesn’t publish an official figure, but it is widely reported to play videos back at about -14 LUFS. The numbers are negative, so -14 is louder than -16. The Peak meter in the Sound Optimizer shows sample peaks; to check the true peak (dBTP) of your finished file, open it in the LUFS & Peak Analyzer.
Quick Settings to Get You Started
Not sure where to begin? Try these settings, then adjust by ear. Every voice and room is a little different.
| Setting | Podcast or voice-over | Music or beat |
|---|---|---|
| Low Cut | 80 to 100 Hz | Off |
| Noise Gate | Around -55 dB | Off |
| De-Esser | 20 to 35% | 0% |
| Bass / Mid / Treble | -1 / 0 / +2 dB | Small changes only if needed |
| Compressor | Threshold -20 dB, ratio 3:1 | Threshold -14 dB, ratio 2:1 |
| Loudness target | -16 LUFS for a podcast, -14 LUFS for video (a mono file reads about 3 LU lower, so aim for about -19 LUFS in mono) | -14 LUFS |
| Download | Mono, 44.1 kHz (or Stereo, 48 kHz for video) | Stereo, 44.1 kHz |
For more tips, read How to Make Your Voice Sound Professional.
Quick Fixes for Common Problems
- My audio distorts when I turn it up. Turn Volume / Gain down a little, move the Compressor Threshold further left or raise the ratio, then try again while watching the Peak meter.
- The ends of my words are cut off. The Noise Gate is set too high. Move it back a few steps until your words sound complete.
- My voice sounds thin or tinny. Lower the Low Cut frequency and reduce the Treble, then raise the Bass by 1 dB.
- The sound feels flat and lifeless. The compressor is working too hard. Lower the ratio and accept a slightly lower loudness.
- The 8D effect disappeared after download. 8D only works in stereo. Choose Stereo before downloading and listen on headphones.
Do Even More with Our Other Free Tools
The Sound Optimizer covers the most common improvements in one place. For everything else, Free Audio Lab has a separate free tool.
Before You Optimize
- Cut out mistakes, coughs and long silences with the Audio Trimmer.
- Combine several recordings into one file with the Audio Joiner & Mixer.
- Get the sound out of a video with the MP4 to WAV Converter, the MOV to WAV Converter or the WebM to WAV Converter.
- Lower background music automatically under your voice with the Auto-Ducker.
After You Optimize
- Make a smaller file for uploading or sharing with the WAV to MP3 Converter.
- Double-check the loudness and true peak of your finished file with the LUFS & Peak Analyzer.
- Change the sample rate for a video project with the Sample Rate Converter.
- Turn your audio into a video for social media with the Audiogram Maker.
When You Only Need One Thing
| I just want to... | Use this free tool |
|---|---|
| Adjust bass, mid and treble | 3-Band EQ |
| Silence background noise and soften harsh S sounds | Noise Gate & De-Esser |
| Change the speed or key of a song | Pitch & Speed Changer |
| Create 8D audio | 8D Audio Maker |
| Add a fade-in or fade-out | Audio Fade Tool |
| Turn a stereo file into mono | Stereo to Mono Converter |
| Find the tempo and key of a track | BPM & Key Analyzer |
You can see every tool on the tools page.
Helpful Guides
- How to Remove Background Noise
- How to Master Audio for Spotify
- How to Make Audio Louder Without Clipping
- How to Mix Vocals and Background Music
- Stereo vs Mono: Which Should You Choose?
- 44.1 kHz vs 48 kHz Explained
- How to Create 8D Audio
Ready to Improve Your Audio?
Now you know what the Sound Optimizer can do and how to use it. Try it on one of your own recordings and compare the result with the original.
Open the free Sound OptimizerFree, no sign-up, and your files never leave your device.