Understanding Speech Quality in a Contact Center

Get to grips with how to measure speech quality in service environments

Understanding Speech Quality in a Contact Centre
Speech AnalyticsInsights

Last Edited: January 17, 2023

Rebekah Carter

Speech is an essential but frequently overlooked aspect of call quality in a contact center.

Speech is a specific subset of audio that captures how well an agent’s spoken voice translates into heard communication for the caller/customer.

There are several ways to measure speech quality, including spoken and automated voice, and measuring this helps extract the expected ROI from contact center investments.

A low speech quality score usually means there are severe technical issues impacting voice and sound relay across the communication lines.

Of course, this can influence the customer and agent experience. However, it may also affect the success of voice technologies, including speech analytics.

What Is Speech Quality?

Speech quality is a subjective measure of how well a listener/group of listeners can interpret human or synthetic speech and receive the intended information.

As the definition suggests, the concept has several traits:

  • It Is Subjective – It’s impossible to assign an outright score to a piece of recorded or live speech. There must be a listener, with quality assessed in the context of the said listener.
  • It Can Be Synthetic – Contact centers can assess the speech quality of IVRs and intelligent voice assistants, alongside that coming from customers and agents.
  • It Is Influenced By Technology and the Environment – Alongside the agent’s speech, the voice channel relays ambient noise from the surrounding environment, and microphone stutters that reduce speech quality.

Just remember, speech quality doesn’t capture how clear the agent’s voice was. Instead, it tries to measure the difference between the agent’s speech in real life – i.e., as heard in the contact center – and what the customer hears – i.e., as heard after passing through the telephony system.

The Industry Standard for Measuring Speech Quality

There are many ways companies can test the voice quality offered by their phone technology. Perhaps the easiest solution is to ask someone to call a business contact number and evaluate the audio quality.

However, since factors like location and time can sometimes affect audio quality, this strategy could deliver limited insights.

Many leading contact center innovators currently have tools to help companies monitor, examine, and measure speech quality more accurately. These typically rely on an industry-standard audio quality measure known as PESQ or Perceptual Evaluation of Speech Quality.

PESQ is an International Telecommunication Union-approved standard for measuring audio quality. It examines everything from audio sharpness and call volume to background noise, variable latency, lag in audio, clipping, and audio interference.

Also, PESQ allows for audio quality testing on multiple types of calls, from mobile and fixed lines to toll-free and toll services, and across VoIP and PSTN networks.

How Does a Speech Quality Test Work?

PESQ speech quality tests often compare audio output at the phone line receiver end to an original voice file on the speaker’s end.

In doing so, contact centers gain comprehensive insights into the voice quality that customers are likely to experience.

Such an approach is more accurate than other strategies for audio quality measurement, which often rely on predictions based on the performance of a network.

To follow this PESQ testing system, try the following four-step process for measuring speech quality:

  1. Set up an in-country server connected to a standard phone line (mobile or landline) that dials a contact number for the business.
  2. The server sends a DTMF dial tone which has been entered into the IVR system.
  3. The IVR connects the test call to a pre-loaded audio file, which plays a voice sample back over the line. The server records this.
  4. Analyze the voice sample to generate a quality score of between -0.5 and 4.5. The higher the score, the better the audio quality.

By sending test calls from in-country servers, voice quality testing strategies done in this way can uncover the genuine experiences of callers from regions across the globe.

Using the PESQ test, companies can more effectively manage SLAs with carriers, make better routing decisions, and benchmark call quality performance for groups in their audience.

Why Should You Measure Speech Quality?

Fortunately, today, measuring speech quality is as simple as using speech technology software like Hammer, Spearline, or Cyara.

By leveraging these tools, companies can avoid overlooking chronic system issues that hold back customer experiences and evade the attention of the contact center team.

Learn more about Hammer’s speech quality testing technology by reading our article: What is VoiceWatch, and How Does It Meet Market Needs?



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