CONCEPT Cited by 1 source
POLQA MOS metric¶
Definition¶
POLQA (Perceptual Objective Listening Quality Analysis, ITU-T P.863) is an objective voice-quality metric that outputs a MOS (Mean Opinion Score) on a 1–5 scale by comparing a decoded audio signal against a reference, modelling human perceptual sensitivities. Higher is better. POLQA is the standard ITU benchmark used to compare codecs (Source: sources/2024-06-13-meta-mlow-metas-low-bitrate-audio-codec).
Scale¶
Standard MOS interpretation (ITU-T P.800 family):
| MOS | Quality label |
|---|---|
| 5 | Excellent |
| 4 | Good |
| 3 | Fair |
| 2 | Poor |
| 1 | Bad |
Used in the MLow post¶
The central comparison:
| Codec / bitrate | POLQA MOS |
|---|---|
| Opus @ 6 kbps NarrowBand | 1.89 |
| MLow @ 6 kbps WideBand | 3.9 |
Meta characterises this as "two-times better quality than Opus". Note: this is the MOS ratio 3.9 / 1.89 ≈ 2.06 — not a doubling in perceived-quality units. MOS is non-linear in perceived quality; a 1.89 → 3.9 shift is roughly "barely intelligible" → "good" on the subjective label scale.
Why POLQA (not PESQ)¶
POLQA (P.863, 2011) supersedes PESQ (P.862, 2001) and explicitly targets HD / WideBand / SuperWideBand audio, which PESQ handled poorly. For codecs that move between band modes (see concepts/narrowband-vs-wideband-audio), POLQA is the correct benchmark.
Caveats named by the source¶
The MLow post does NOT disclose:
- The reference signal set used.
- Whether the scores are mean or median across a corpus.
- Test conditions (single-channel, multi-channel, background noise, etc.).
- The full POLQA vs bitrate curve across operating points (Figure 2 is shown in the post but without tabulated numbers).
Seen in¶
- sources/2024-06-13-meta-mlow-metas-low-bitrate-audio-codec — canonical codec benchmark metric cited side-by-side with compute-complexity claims.