What is PESQ?

PESQ is an objective and recognized industry-standard audio quality measure.

PESQ stands for the Perceptual Evaluation of Speech Quality. Spearline uses this in its global in-country number testing. This objective and recognized industry-standard audio quality measure takes into consideration characteristics such as:

  • Audio Sharpness
  • Call Volume
  • Background Noise
  • Variable Latency or Lag in Audio
  • Clipping
  • Audio Interference

How to tell what ‘good’ and ‘bad’ sound like

The test compares an audio output (at the phone line's 'listener' end) to the original voice file (played on the 'talker' side) to create a fully unbiased and objective indicator of the actual audio being heard. This is more accurate than other methods of audio quality measurement which often rely on audio quality predictions based on network performance. PESQ returns a score from -0.5 to 4.5, with higher scores indicating better quality.

PESQ score definitions are typically grouped into six bands:

  1. 1.00 - 1.99 No meaning understood with any feasible effort
  2. 2.00 - 2.39 Considerable effort required
  3. 2.40 - 2.79 Moderate effort required
  4. 2.80 - 3.29 Attention necessary; a small amount of effort required
  5. 3.30 - 3.79 Attention necessary; no appreciable effort required
  6. 3.80 - 4.50 Complete relaxation possible; no effort required

It’s worth remembering, of course, that ‘good audio quality’ can vary from one country to the next. What one might expect in Germany would be unachievable in Brazil.

If you’re proactively measuring the audio quality you’re achieving, and checking that against a country-by-country benchmark, you can make informed decisions about which telecoms providers you use, and how you route your calls.