Podcast “compression” describes two separate processes. Dynamic-range compression reduces the gap between quiet and loud moments. Data compression reduces the download size with MP3 or AAC. The best result uses both carefully: a stable mix gives the codec an easier signal to encode.
Step 1: clean the edit before encoding
Remove false starts, long silences, severe background noise and unused tails. Do not gate every breath or make the room tone jump unnaturally. Editing five minutes from an hour cuts the audio payload by about 8%, with no codec penalty at all.
Step 2: make dialogue consistent
Set clip gain so speakers enter the compressor at reasonably similar levels. A gentle ratio and moderate gain reduction can control normal variation; automation or manual gain is better for large differences. A limiter should catch occasional peaks, not remain pinned down for the entire conversation.
Apple recommends overall program loudness around -16 dB LKFS, within one decibel, and true peak no higher than -1 dBFS. Other hosts may specify a different target, so treat the destination’s requirement as authoritative.
Step 3: decide between mono and stereo
Centered speech does not become more engaging simply because it is stored in two identical channels. Mono is efficient for interviews, lectures and narration. Use stereo when music, ambience, spatial storytelling or left/right microphone placement contributes to the experience.
Step 4: choose format and bitrate
| Program type | Starting setting | Approx. one-hour MP3 size |
|---|---|---|
| Voice-only mono | 80 kbps MP3 | 36 MB |
| Premium spoken word mono | 96 kbps MP3 | 43.2 MB |
| Stereo talk show | 128 kbps MP3 | 57.6 MB |
| Music-rich stereo show | 160–192 kbps MP3 | 72–86.4 MB |
Apple accepts MP3 or AAC for RSS audio and publishes broader bitrate ranges: 64–128 kbps mono and 128–256 kbps stereo at 44.1 or 48 kHz. It also notes that AAC delivers better quality than MP3 at the same bitrate. Your podcast host may make another transcode, so check its current documentation before uploading.
Step 5: audition the encoded file
Listen to the export itself, not only the editing session. Inspect “s” sounds, laughter, applause, theme music and overlapping speech. These dense or noisy moments reveal warbling and high-frequency smearing first. Test on headphones and a phone speaker at normal listening volume.
Step 6: keep the master
Archive the final WAV or FLAC alongside the session and a text record of export settings. If a network asks for a different codec next year, you can create it directly from the lossless master instead of transcoding an old MP3.
Common compression mistakes
- Encoding before the edit is final: every revision risks another lossy generation.
- Using stereo for duplicated mono: spends bits without adding useful information.
- Chasing loudness with a limiter alone: produces tiring, distorted speech.
- Ignoring cover art: a huge embedded image can erase file-size savings.
- Judging only quiet dialogue: codec problems usually appear in the hardest section.