Key takeaways
- Voice quality testing is the systematic measurement of audio characteristics during calls to validate clear communication between callers and contact centers.
- Automated testing using pre-recorded voice samples provides objective, scalable results superior to manual testing methods.
- PESQ scores range from -0.5 to 4.5, with scores above 3.5 indicating good quality and scores below 2.5 requiring attention.
- Proactive, continuous testing helps identify issues before customers complain, reducing mean time to resolution.
- Regular testing verifies that carriers meet their SLAs and that audio is not being degraded by transcoding.
We’ve all experienced an interaction with a business’s interactive voice response (IVR, an automated phone system that interacts with callers) system where poor voice quality makes it almost impossible to complete an automated task or get “self-help” when you need it. Listening to broken prompts, hearing jitter or noise on the line, along with any other audio quality issue makes it hard to understand the navigation options. Poor voice quality can lead to misunderstandings, stress and, sometimes, the complete abandonment of calls.
Having poor voice quality affecting your personal calls is frustrating for all involved, but having degraded audio quality can be damaging to a business. So how do you know when voice quality is potentially impacting your organization’s phone numbers experience? For a global business, customer call experiences can vary based on their location and the respective contact number they rang. To accurately assess callers’ experiences, you must test your network’s voice call quality.
Voice quality testing is the systematic process of measuring and analyzing audio characteristics during phone calls to confirm clear, reliable communication between callers and contact centers or IVR systems.
How do you conduct a voice quality test?
The most effective and reliable method of testing voice call quality is to use a pre-recorded voice sample. This test compares the audio output (at the listener’s end) to the original voice file (played on the ‘talker’ side) to create unbiased and objective metrics of the true audio quality that the listener experiences.
Here’s a brief outline of how Cyara conducts a voice call quality test:
- Using a predefined test script, Cyara uses the carrier network to dial your toll-free or other inward dialing number.
- The test script navigates your IVR call flow just as a customer would.
- Your IVR plays back the pre-recorded WAV files to the script just as it would to an actual caller.
- The system analyzes the WAV file playback to produce a dependable audio quality score.
By originating test calls within the same global region as your normal call patterns, voice quality testing in this manner uncovers the genuine experiences of callers worldwide. It also provides full control for conducting these tests at any time, whether it’s day or night.
Manual vs. automated testing: In contrast, some organizations use manual testing, in which they ask employees, friends, family, or freelancers to make calls and rate quality. However, this method isn’t scientific and is frequently unreliable. A person’s voice quality experience is subjective, they can’t provide accurate measurements of all characteristics, and they won’t always be available when needed. Relying on this labor-intensive process, particularly across a multitude of global contact numbers, is costly and potentially unmanageable. Automated testing using pre-recorded samples provides consistent, objective, scalable results available on demand.
What metrics does voice quality testing measure?
Using this type of voice quality testing, the call recording will be analyzed and compared with the original voice sample through an established, objective voice quality measure known as Perceptual Evaluation of Speech Quality (PESQ).
PESQ is an International Telecommunication Union (ITU) standard for measuring audio quality. PESQ scores range from -0.5 to 4.5, where scores above 3.5 generally indicate good quality, scores between 2.5 and 3.5 suggest acceptable quality, and scores below 2.5 typically indicate poor quality requiring attention.
PESQ measures the following audio characteristics:
- Audio sharpness – clarity and crispness of speech
- Call volume – appropriate loudness levels
- Background noise – unwanted ambient sounds
- Variable latency – inconsistent delay in audio transmission
- Audio lag – delay between speaking and hearing
- Clipping – distortion from audio signal cutoff
- Audio interference – disruptions from external signals
This enables you to test call quality effortlessly across all call types, including mobile, fixed-line, toll, toll-free, Voice over Internet Protocol (VoIP, phone calls made over the internet), and Public Switched Telephone Network (PSTN, traditional landline phone systems), using an agreed and internationally recognized standard.
Through ongoing voice quality testing, you will have the data you need to guarantee your customers are experiencing high audio quality at all times. You’ll also better understand how, when and why this varies, especially when calling from different locations.
How can testing voice call quality help your business?
We’ve discussed how voice call quality testing works, but what should you do with this information?
1. Help your engineers to get ahead of voice quality issues
Proactive voice quality testing allows you to receive alerts at the earliest possible moment regarding potential issues. While your engineering team may be monitoring the performance of your internal network, they have no control and, often, no visibility of what’s happening on the external network. As such, poor voice quality issues are often unknown unless a customer chooses to make a complaint. This means that the fault can be ‘live’ for a significant period before it’s identified. And that your customers are being negatively affected.
Continuous proactive voice quality testing is necessary to ensure you receive alerts as soon as issues occur. The test results will also provide you with the intelligence you need to promptly fix the problem. Cyara’s voice quality testing, for example, comes with full call detail records (CDRs, logs containing information about each call) that allow you to quickly pinpoint issues, and call recordings allowing you to listen to instances of poor quality. Leveraging the call detail information, you can then troubleshoot more quickly and reduce your mean time to resolution (MTTR).
2. Protect your brand and your reputation
The ultimate aim of having proactive monitoring, paired with alerts for voice quality monitoring is to protect your brand. Any degradation in voice quality will lead to a reduction in your customer’s experience, which, in turn, will cause damage to your brand’s reputation. By promptly identifying voice quality issues and having the necessary insights for quick adjustments to your contact center platform, you can proactively manage your interactive customer journeys, safeguarding your reputation.
3. Test the standard of voice call quality being provided by your carriers
Businesses typically rely on their carriers to provide them with an agreed level of service. And, telecom companies often rely on their own partners to ensure their voice calls correctly move along the full call path. In the case of an international call, that path may have a variety of potential routes that it could follow, with hops and handovers made to various carrier partners along the way.
Yet, despite agreed contracts and service level agreements (SLAs, contractual commitments defining expected service performance), businesses are often unaware of the true performance that their carriers are providing them with. Likewise, carriers are frequently blind to the performance of their partners’. For example, some may be transcoding (compressing audio files using different codecs—algorithms that encode and decode audio data) at busy times to save on data. Even if calls are not being dropped completely, this transcoding is likely to result in a loss of voice quality. And, because this may be happening spontaneously, it can be difficult to spot without an ongoing testing and monitoring tool.
Conclusion
Voice quality testing is essential for ensuring that your contact center and IVR deliver a smooth and satisfying customer experience. By testing your voice quality proactively, you can quickly detect and resolve any issues that may affect your call quality, such as network congestion, packet loss, jitter, or latency. You can also test different call flows and routes across your network, and compare the performance of your applications and providers. This way, you can make better decisions on which providers and routes to use for your voice calls. Moreover, you can verify that your carrier meets your SLAs and that your calls are not transcoded by any intermediate devices. Voice quality testing can help you improve your customer service, reduce costs, and increase brand loyalty.
Frequently Asked Questions
A PESQ score above 3.5 (on a scale of -0.5 to 4.5) generally indicates good voice quality. Scores between 2.5 and 3.5 are acceptable, while scores below 2.5 typically indicate poor quality that needs investigation.
For optimal results, voice quality should be tested continuously through automated monitoring. This ensures issues are detected immediately rather than waiting for customer complaints. At minimum, testing should occur during peak call times and across all geographic regions you serve.
Common causes include network congestion, packet loss, jitter, latency, transcoding by intermediate carriers, codec incompatibilities, and insufficient bandwidth. External network issues beyond your internal infrastructure can also significantly impact quality.
Voice quality testing is the process of measuring the audio quality that callers experience when interacting with your contact center or IVR system. It uses pre-recorded voice samples to produce objective, measurable scores of audio clarity rather than relying on subjective human feedback.
Cyara dials your toll-free or inward dialing number using a predefined test script, navigates your IVR just as a real customer would, and analyzes the audio playback to produce a dependable quality score. Tests are originated within the same global region as your normal call patterns to reflect genuine caller experiences.
Voice quality is measured using Perceptual Evaluation of Speech Quality (PESQ), an International Telecommunication Union (ITU) standard. It accounts for characteristics such as audio sharpness, call volume, background noise, latency, clipping, and audio interference.
Voice quality testing can be applied across all major call types, including mobile, fixed-line, toll, toll-free, VoIP, and PSTN, using the PESQ standard as a consistent benchmark.
Poor voice quality issues often go undetected until a customer complains, meaning the fault can be live for a significant period before it is identified. Continuous proactive testing ensures your team receives alerts as soon as issues occur, reducing the time customers are negatively affected.
Cyara’s voice quality testing provides full call detail records (CDRs) and call recordings that help engineers quickly pinpoint the source of audio problems. This data allows teams to troubleshoot faster and reduce mean time to resolution (MTTR).
Yes, ongoing testing allows businesses to confirm whether their carriers are meeting agreed service level agreements (SLAs). It can also detect issues like transcoding, where carriers compress audio files during busy periods, resulting in a loss of voice quality that may otherwise go unnoticed.
Degraded audio quality can lead to customer misunderstandings, call abandonment, and damage to brand reputation. Proactive voice quality monitoring helps businesses identify and resolve issues quickly, protecting the customer experience and brand loyalty.
