Spirent circle logo


Speech Intelligibility Evaluation Highlights Differences Between LTE Public Safety Devices


Speech intelligibility is a critical requirement for first responder communications devices. In the real world of noise-filled emergency environments, being misunderstood or having to repeat oneself can have catastrophic consequences.

Spirent recently became the first organization to offer a Speech Intelligibility Evaluation service based on the ABC-MRT16 algorithm developed by the U.S. National Telecommunications and Information Administration (NTIA). Following a rigorous test methodology, we conducted a benchmarking study to compare the intelligibility performance of four commercially-available public safety LTE devices.

PS-LTE makes four compelling promises for emergency services agencies:

  • First responder networks, largely voice-centric today, will be able to leverage what the average smartphone user has had for a decade: high speed data, live video, location tracking, group messaging, etc.

  • LTE’s enormous device vendor ecosystem and access to an app-enabled environment will provide unparalleled choices and innovation.

  • The economics of leveraging commercial LTE network components, existing commercial networks and the vendor ecosystem will result in a favorable cost structure.

  • Interoperability between agencies (a driving force behind the funding of FirstNet) will be enabled by software within a unified network.

When device vendors and mobile operators choose to serve the public safety market, they have a vested interest in ensuring that they’re doing everything possible to maximize speech intelligibility. A key part of this assurance is selecting the right testing algorithm along with highly specialized test equipment, environment and expertise.

This white paper gives an overview of the requirements, insight into the methodologies used, and comparisons in the performance of the four devices, without specifics on manufacturers and models. The results were unpredictable, eye-opening and prove that superior quality is still achievable in harsh conditions.

Download the White Paper