PESQ - What is it and how could it transform your customer experience?

How do you know how good your audio quality is? Put yourself in your customer’s shoes.
On Tuesday 20 November 2018 by Mika Wilson

The first blog in our series on audio quality outlined the importance of audio quality for contact centres. So we’ve established the need for good audio quality to improve customer experience, agent experience, and vital metrics like average handling time and first call resolution.

Audio quality can be lost for all sorts of reasons. One of the common situations is where your telephone provider is working with multiple partners (downstream carriers) and one or more is compressing files to save bandwidth (transcoding).

So, how do you know how good your audio quality is?

The simple answer - put yourself in your customer’s shoes.

The only way to truly test the audio quality your customer is experiencing (and hence their perception of your brand when they call you) is to dial your numbers from the same country and same telephone lines as them.

This gives you the outside-in view of your customers’ experience and can alert you to customer-impacting issues that you would otherwise be completely unaware of.

And what’s PESQ?

We use an objective, recognised industry standard audio quality measure called PESQ (Perceptual Evaluation of Speech Quality) in our global in-country number testing.

PESQ takes into consideration characteristics such as:

- Audio sharpness

- Call volume

- Background noise

- Variable latency or lag in audio

- Clipping

- Audio interference

The test compares an audio output (at the ‘listener’ end of a phone line) with the original voice recording (played at the ‘talker’ side), to form a completely objective measure of the real audio being experienced. This is more accurate than other methods of measuring audio quality, which often rely on predictions of audio quality based on network performance.

PESQ returns a score from -0.5 to 4.5, with higher scores indicating better quality.

What does ‘good’ or 'bad' audio 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 we've 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; 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
How do they sound?

It’s not a big leap to imagine how different your customer would feel about a call to your contact centre where they experienced audio quality of 1.11, as opposed to 4.33 on the PESQ scale. With audio quality of 1.11, a conversation would be impossible. And at 2.20, or 2.63, imagine how many “Sorry, could you repeat that”s they might have to say, how many times they’d have to repeat their account number and how much longer it might take them to resolve their issue. They may just give up and (hopefully) try again later.  

It’s worth remembering, of course, that ‘good audio quality’ can vary from one country to the next. What we 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.

Find out more about how you can proactively test your contact numbers, and get an objective measure of audio quality on your lines.