Audio Quality Still a Problem for Wireless Providers
Nearly 40 percent of mobile voice calls have end-user-experienced quality low enough as to be highly churn-inducing, according to test data gathered by Ditech Networks. The audit of 630 million live mobile calls showed that 39 percent had mean opinion scores low enough that the providers are in danger of customer churn, Ditech says.
That data stands in contrast to tests by mobile network engineers that often finds the network itself is performing as it should, which is to say at a level that would provide satisfactory MOS scores.
The problem, says Ditech, is that the deterioration is occurring outside the network, between the user handset and other devices such as Bluetooth headsets; high levels of ambient noise or distortion caused by multiple signal paths, such as voice bouncing off the windshield of a vehicle as the user is speaking.
The survey data came from 16 global mobile service providers operating in 12 countries, and suggest that the percentage and number of voice calls whose quality is degraded by impairments in the caller’s ambient environment are an understated issue, even when the network itself is working well from network transmission end point to end point.
Ambient noise, or noise that originates in the caller’s environment and enters the device’s microphone, was rated “objectionable” on up to 50 percent of all calls in some regions.
Acoustic echo, which is often caused by mobile handsets and headsets, was rated “objectionable” on up to 11 percent of all calls in some regions.
Voice level mismatch, which makes it sound like a caller is speaking either too loudly or too softly, was rated “objectionable” on up to 28 percent of all calls in some regions, for example.
As you might expect, impairments were more an issue in developing markets. But even in mature markets such as the United States and Western Europe, 23 percent of all calls fall below the industry minimum.
In rapid growth markets, such as the Middle East, India and South America, 59 percent of all calls fall below the industry minimum. The total number of calls rated unacceptable ranges from 20 percent to 40 percent in each direction. With a voice quality assurance correction applied, the total number of unacceptable calls drops to between five percent and 20 percent.
The number of calls with objectionable ambient noise ranges from 15-35 percent in each direction. With voice quality assurance measures applied, the number of calls with objectionable noise dropped to between two and 15 percent.
The number of calls with objectionable echo ranges from five percent to 10 percent. With voice quality measures applied, the number of calls with objectionable echo was reduced to zero.
The audits were conducted using Experience Intelligence (EXi), a technology developed by Ditech that quantifies the impact of voice quality impairments caused by the places where people make calls, codec impairments, and mobile devices like phones and headsets.
The audit data was used to derive an R-Factor, a rating system developed by the International Telecommunications Union to assess customer satisfaction with voice quality.
The measured R-Factors were converted to Mean Opinion Scores, widely used in the mobile services industry to rate voice quality on a scale of one to five, where five is best (a perfect audio experience) and one is the worst (completely unacceptable).
The ITU sets the minimum level of acceptable voice quality at a MOS score
of 2.5.
In some ways the test data is part of a broader trend. Where in the past voice quality was something a service provider could assume was controlled primary within a network, and not by factors on the other side of a network interface unit, punch-down block, router, gateway or radio, quality now is directly affected by end user equipment and the use of that equipment.
Where overall quality once was a clearly-demarcated issue in a business or consumer environment, quality now is materially affected by customer environment and equipment issues that are not part of the network.
And since the service provider typically is deemed to be the entity responsible for maintaining quality of experience, every provider will have to take more measures to protect experience beyond the network termination, or advise customers that they must take measures to provide the same protections.
Roughly the same sort of change will be seen as more providers start offering video services as well. As any cable operator can attest, consumers expect all their in-home video equipment to work together when video service is purchased. And that means more involvement, one way or the other, in setting up complicated in-home video systems that include all sorts of devices the network services operator actually doesn’t supply, own or want to touch.
Is the service process therefore becoming more complicated? Yes, to be sure. Will just about all service providers need to start operating on the customer side of the interface? In an increasing number of instances, yes. IP
