Mumble

Here's Mumble — a fully working audio clarity tool. Here's what it does:

How it works: It runs your audio through the Web Audio API using real DSP processing

a band-pass filter that isolates the human voice range (300–4000 Hz), a gain reduction 

on everything outside that band, and a presence boost at 2–5kHz where consonants live 

(the "s", "t", "f" sounds that make speech intelligible).

Features:

Drop any video or audio file (MP4, MKV, AVI, MOV, MP3, WAV, etc.)

5 presets: Standard, Heavy Mumble, Thick Accent, Action Film, Gentle Lift

Manual controls for voice boost, background dim, frequency range, presence, and noise gate

Plays back the enhanced audio in-browser with a waveform display

Downloads the result as a WAV file you can use with your media player or video editor

The processing all happens locally in your browser — no upload to any server.