StudioWavePro — Online Audio Editor with 48+ Studio Tools

body { background: #0a0b12; color: #e5e7eb; font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; max-width: 800px; margin: 0 auto; padding: 40px 24px; line-height: 1.6; } h1 { color: #818cf8; font-size: 32px; margin-bottom: 16px; } h2 { color: #22d3ee; font-size: 20px; margin-top: 32px; margin-bottom: 8px; } ul { padding-left: 24px; } li { margin: 4px 0; } a { color: #818cf8; } Low Pass Filter — Free Online Audio Tool | StudioWaveProCut off high frequencies (remove harshness)

A low pass filter lets the lows through and turns down everything above the cutoff. StudioWavePro’s version gives you the two controls that matter: Cutoff (100 Hz–20 kHz, default 2 kHz) sets where the highs start to disappear, and Resonance/Q (0.1–10) shapes the knee — low Q rolls off smoothly and politely, high Q adds the peaky, vowel-like emphasis at the cutoff that synth filters are famous for.

Both controls respond live during preview, which makes this as much a creative effect as a corrective one: sweep the cutoff down while a track plays and you get the "music from the next room" or underwater feel; park it around 6–8 kHz to shave digital harshness or hiss off a bright recording without dulling the body.

When to use

Soften a harsh or brittle recording by trimming the extreme highs.
Reduce hiss living above the useful content of a voice recording.
Create the muffled "behind a wall / next room" effect for film and game audio.
Make the underwater or lo-fi radio texture (low cutoff, some resonance).
Tame cymbals that splash over everything in a live recording.
Add synth-style resonant sweeps to electronic material.

How to use

Click "Open Low Pass Filter" below to launch the editor.
Drop in any audio file — MP3, WAV, OGG, M4A and FLAC are all supported.
Press "Play preview" and drag the Cutoff slider down from 20 kHz until the unwanted highs are gone.
Adjust Resonance: leave near 0.7 for transparent filtering, push higher for an audible synth-like peak at the cutoff.
Click Apply, then download as WAV or MP3.

Tips

For de-harshing, start around 8–10 kHz and come down slowly — most "digital edge" lives up there, and you keep all the presence below.
The "next room" effect: cutoff around 300–600 Hz. Underwater: 200–400 Hz with Q around 2–4.
High Q (above ~5) creates a strong resonant peak that can get loud at the cutoff frequency — lower the volume or normalize afterwards if it spikes.
Hiss reduction with a low pass is a trade: every dB of hiss you remove above the cutoff also costs sparkle. Cut as high as possible while still helping.
Need the mirror image — removing rumble and mud instead of highs? That’s the High Pass Filter.

Frequently asked questions

What does a low pass filter do to audio?: It lets frequencies below the cutoff pass and progressively quiets everything above it. Practical translations: less harshness, less hiss, a darker or more muffled tone — depending on where you set the cutoff.
How do I make audio sound muffled, like it’s in another room?: Open the Low Pass Filter, press Play preview, and drag the cutoff down to roughly 300–600 Hz. That reproduces how walls absorb highs while bass passes through. Apply and download when it sounds right.
What does the resonance (Q) control do?: It shapes the transition at the cutoff. Low Q (0.5–1) gives a smooth, natural roll-off for corrective work. High Q (3–10) boosts a narrow band right at the cutoff — the classic squelchy synthesizer filter sound, especially audible when you sweep the cutoff live.
Can a low pass filter remove hiss?: It helps when the hiss sits above the useful content — common with voice, which lives mostly below 8 kHz. Set the cutoff just above the voice’s brightness and the hiss drops noticeably. For broadband noise mixed into the same range as the content, filtering alone can’t separate them.
What cutoff frequency should I use?: Don’t pick a number — pick a sound. Press Play preview and sweep: 10 kHz+ is subtle de-edging, 4–8 kHz darkens noticeably, 1–2 kHz sounds filtered, below 600 Hz reads as muffled/special-effect. The right value is wherever your ears say stop.
Is the filtering destructive to quality?: The filter runs at full floating-point precision — the same biquad math as desktop audio software. Whatever passes the filter is untouched in quality; export as WAV for a lossless file.

StudioWavePro is a complete audio editor with 48+ studio-grade tools in one workspace. Trim, master, EQ, time-stretch, denoise, remove vocals, detect BPM and musical key, generate metronomes, and more. Editing tools

Audio Trimmer — crop a track to a selected region

Mute Section — silence a selected region

Reverse Audio — play the track backwards

Fade In/Out — ramp volume at start or end

Silence Trimmer — strip leading and trailing silence

Silence Gap Inserter — insert silence at a chosen position

Audio Looper — repeat a section N times

Audio Splitter — cut a track into multiple parts

Audio Merger — join multiple files end-to-end

Silence Splitter — auto-split at silent gaps

Crossfade Joiner — join clips with overlapping fades

Time and pitch

Speed Changer — speed up or slow down (with optional pitch preservation)

Pitch Shift — change pitch without changing tempo

Tempo Detector — estimate the BPM of a music track

Key Detector — estimate the musical key

Metronome Generator — create a click track at any BPM

Effects

Volume — make a track louder or quieter

Bass Boost — lift the low end

Treble Boost — lift the high end

Low Pass Filter — cut off high frequencies

High Pass Filter — cut off low frequencies (remove rumble)

Equalizer (3-band) — low / mid / high tonal shaping

Equalizer (10-band) — fine-grained tonal control

Echo — add repeating echoes / delay

Distortion — overdrive, fuzz, and lo-fi grit

Stereo Balance — shift the L/R center of a stereo mix

Stereo Widener — make stereo narrower or wider

Vocal Remover — karaoke (center-channel removal)

Hum Remover — strip 50/60 Hz mains hum

Mastering and analysis

Normalize — maximize volume without clipping

Compressor — even out loud and quiet parts

Loudness Meter — measure peak, RMS, and LUFS

Mono Converter — collapse stereo to mono

Channel Extractor — pull L, R, Mid, or Side

Sample Rate Converter — resample to 44.1, 48, or 96 kHz

Polarity Inverter — flip waveform for phase alignment

DC Offset Remover — center waveform around zero

Audio Visualizer — render an animated video from audio

StudioWavePro supports MP3, WAV, OGG, M4A, and FLAC files. Exports include WAV and MP3. This app requires JavaScript to run. Please enable JavaScript in your browser.