This blog is by Ismo Matilainen at Nokia Networks.
If you think you’ve heard the best HD voice quality on VoLTE wideband, then you “ain’t heard nothing yet”. Music fans – get ready for a whole new listening and voice experience with Enhanced Voice Services (EVS) Codec.
Nokia is one of the developers of the new EVS Codec and 3GPP standardization work (in Release 12), that was completed in December 2014 and enables vastly improved voice quality, network capacity and advanced features for voice services over LTE and other standardized radio access technologies. EVS is the first 3GPP conversational codec offering up to 20 kHz audio bandwidth, delivering speech quality that matches other audio input such as stored music while offering high robustness to delay jitter and packet losses.
Currently, the best voice codec in VoLTE is provided by wideband AMR (AMR -WB). EVS Codec, however, provides equally high quality audio for both voice and music. Typically, for normal VoLTE (or VoWiFi) voice calls, AMR-WB is enough to provide excellent HD voice quality, at least for those of us who aren’t opera singers… So what benefits can EVS provide other than the ability to combine superior voice and music experience?
The main attributes affecting the subjective speech and audio quality are audio bandwidth, signal type, channel conditions and available bitrates. Typical speech codec can only handle a small number of lost frames (up to about 3%) without severe effects. EVS Codec, however, is capable of handling a loss of over 10% of the frames and can still provide acceptable voice quality.
EVS provides significantly improved quality over AMR-WB at similar bitrates. As an example, VoLTE uses AMR-WB 23.85 kbit/s today compared to only 9.6 kbit/s bandwidth needed with EVS to achieve the same quality.
So for operators, the main benefit of implementing this new Codec is being able to provide better voice and music experience in spite of poor conditions (such as low bandwidth), but how long will it be before we see it in general use? Typically, new standards take about 1-1.5 years before they’re implemented, but there is a sense of urgency here. Likewise, consumers typically upgrade their devices every 1.5-2.5 years (benchmarks are US and Korea), and given the growing interest in music-related operator services, the future for EVS looks bright.
Want to take a deeper dive into this topic? Read our new White Paper “The 3GPP Enhanced Voice Services (EVS) codec“.
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