Open the Reddit post that has the audio you're after. Copy the URL - it doesn't matter if it's reddit.com, old.reddit.com, or a mobile share link.
Open YouTube to MP3 Converter and paste the link by clicking the Paste link button in the toolbar, or simply press Ctrl+V on Windows or ⌘+V on Mac. You'll see the post title and a thumbnail once it's parsed.
Tip: The program can also watch your clipboard automatically — if you copy a link while the app is open, it will offer to add it right away. You can enable this option in Preferences → General → add links from the clipboard automatically.
Click Start all to download the entire list, or click the Start button on an individual item to download only that one. The converter extracts just the audio stream — no video data is downloaded — and converts it to MP3. This takes a few seconds for a typical clip.
The MP3 file appears in your download folder, named after the post title. Right-click the entry and choose Locate saved file to get there or click the Locate button.
Animated GIFs posted on Reddit look like videos but carry no audio track at all. You can tell the difference by the volume slider — if the player has one, there's real audio. If it just loops silently, it's a GIF.