What is PESQ?


Whenever your customer or agents face poor audio quality, their phone conversations will drag. This causes frustration and fatigue for both parties and can lead to negative experiences. Not only that, but it hampers your call duration and first call resolution rates, which in turn impacts your bottom-line. This blog will help you to better understand PESQ (Perceptual Evaluation of Speech Quality) and its role in delivering top-notch audio quality to your customers.


The Impact of Poor Audio Quality

Audio quality degradation and loss can occur for various reasons. Commonly, a call between two parties passes through various network providers before it reaches its final destination. Each of these providers have distinct policies on transcoding and capacity management. But, organizations typically have very little visibility along this call path, so are often unaware when issues do occur. Therefore, calls may be transcoded without your knowledge or agreement.

Poor telephone service quality can lead to significant cost implications for businesses like yours. As call durations increase due to unclear conversations and the need to repeat key information multiple times, your operational costs also rise. Furthermore, subpar audio quality can lead to declining revenues as customers look for alternatives and potential sales opportunities are lost. But how can you determine if your organization faces an issue with telephone audio quality?

Our global testing and monitoring solutions let you assess the quality of your critical contact numbers using the internationally-recognized PESQ standard.


PESQ Explained

PESQ is a key component of Cyara’s number monitoring. This industry-standard audio quality measure is both objective and internationally recognized. It takes into account various critical characteristics, including:

  • Audio sharpness
  • Call volume
  • Background noise
  • Variable latency 
  • Audio lag
  • Clipping
  • Interference

This test compares the audio output at the 'listener' end of the phone line with the original voice file played on the 'talker' side. This comparison offers a wholly unbiased and objective indicator of the actual audio that people hear. It is much more accurate than other audio quality measurement methods, which often rely on predictions or even subjective estimates. In your results, you will be provided with the resultant PESQ score, ranging from 1 to 4.5. The higher scores indicate a better level of audio quality.


But what about Mean Opinion Score or MOS?

You may be familiar with a Mean Opinion Score or MOS. MOS scores are derived from PESQ scores by using a statistical process called calibration. Calibration ensures that MOS scores are consistent with human judgment. Or in other words, MOS scores are essentially a human-readable version of PESQ scores. The MOS score is represented in the output provided by the Cyara platform when voice quality measurement is captured.


What Do ‘Good’ and ‘Bad’ Audio Sound Like?

Typically, PESQ scores are categorized into six bands. The audio samples provided below for each band represent actual recordings of audio quality tests conducted by Cyara on our 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 above, it's easy to see how frustration can lead a customer to abandon a call when they encounter a low audio quality score. In such cases, a productive conversation between both parties becomes virtually impossible. For conversations falling within the range of 2.00 to 2.79, there might be a slight improvement, but it’s also likely to include phrases such as, "Could you repeat that?" or "Sorry, I can't hear you". Typically, this leads to significant delays in resolving issues and, eventually, customer frustration that might lead to call abandonment.

It’s worth remembering, of course, that ‘good audio quality’ can vary from one country to the next and even from one carrier line or contact number to the next. What may be considered as acceptable in the United States could be deemed unachievable in Brazil. This is where Cyara’s in-country benchmarks add value. You have the flexibility to create the dialing patterns that align with your business needs, dialing from within the country where you want to measure quality.

By proactively assessing your audio quality and benchmarking over time, you can make more informed decisions. You can also determine which telecommunications providers to choose and how best to route your calls. This approach enables you to adapt and optimize your telecommunications approach to meet the distinct needs and expectations of each region in which you operate.