What Is: PESQ?

What is PESQ? Spearline explains how it can transform your customer experience.


The impact of poor audio quality

When either your customer or your agent fails to connect with good telephone audio quality, the conversation will eventually take longer to conclude, leaving both sides extremely frustrated and fatigued from such a terrible experience. Not only that but your first call resolution/first-time fix rate is affected as well as average call times – with an immediate impact on your bottom line.

Audio quality can degrade and be lost for all manner of reasons. A common scenario is where a call between two parties transits multiple network providers, each having different network policies around transcoding and capacity management.

Telephone service quality can have significant cost implications for a business. Operational costs can escalate as call durations increase because conversations are hindered and key information must be repeated for accuracy.  Revenues can suffer as frustrated customers take their business elsewhere or new sales fail to materialize due to poor audio quality. But how does a business find out if it has a problem with telephone audio quality?

Spearline’s testing solutions let you test your business-critical contact numbers using over 70 in-country points of presence worldwide. This internationally-recognized standard titled ‘PESQ’ is used for measuring audio quality that takes into account parameters like variable delays, noise on the line, and clipping of audio.

PESQ Explained

PESQ stands for 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:

  1. Audio sharpness
  2. Call volume
  3. Background noise
  4. Variable latency or lag in audio  
  5. Clipping
  6. Audio interference

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.

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

PESQ score definitions are typically grouped into six bands.
The following audio samples for each band are real recordings of audio quality tests Spearline has run on customers’ international contact numbers:

1.00 – 1.99  No meaning understood with any feasible effort

2.00 – 2.39  Considerable effort required

2.40 – 2.79  Moderate effort required

2.80 – 3.29  Attention necessary; a small amount of effort required

3.30 – 3.79  Attention necessary; no appreciable effort required

3.80 – 4.50  Complete relaxation possible; no effort required

From the examples listed above, it’s very obvious how a customer could be frustrated and abandon a call where they experienced the audio quality of 1.11. A conversation between both sides would be completely non-viable. Conversations ranging from 2.00 – 2.79, would improve only slightly but would involve constant “could you repeat that?” or “sorry, I can’t hear you” which would further delay any problem getting resolved, frustrating the customer and possibly abandoning the call.

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.

But 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.

 *Be sure to connect with Josh O’Farrell on LinkedIn here.


New to Spearline?
If you are new to Spearline and would like to find out more about how you can benefit from our platform, we would love to speak with you. Please send us a brief message, and we will be in contact with you shortly.

About Us

Spearline is a technology company that proactively tests toll and toll-free numbers for connectivity and audio quality globally. It enables organizations to provide uninterrupted services to customers around the world. For further information, or if you have any further questions please get in touch with us.


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