POLQA

POLQA, short for Perceptual Objective Listening Quality Assessment, is an ITU-T standard for predicting the perceived quality of speech signals in telecom networks and codecs. It is the successor to the earlier PESQ method and extends quality assessment to narrowband, wideband, and super-wideband signals, including modern voice codecs and streaming scenarios. The standard yields a MOS-like score, often referred to as MOS-LQO (Listening Quality Objective), on a 1 to 5 scale where higher values indicate better perceived quality.

Technical approach: POLQA compares a reference signal with a degraded test signal using a perceptual speech processing model. The model simulates human auditory processing, including filtering in perceptual bands, loudness adaptation, and nonlinear processing, followed by a cognitive-level evaluation. The method includes time alignment to compensate for delays and sample-rate differences, and is designed to be robust to typical network impairments such as delay, jitter, and mild packet loss. The output reflects perceived listening quality rather than mere signal fidelity.

Applications and adoption: POLQA is widely used in the telecom industry and by device and service providers to evaluate voice codecs, IP telephony, mobile networks, and streaming services. It supports quality monitoring, codec development, and standardization work, serving as a benchmark for objective speech quality assessment and enabling comparability across measurement setups.

See also: PESQ; MOS; ITU-T. POLQA is implemented in various measurement tools and software used in research, development, and network quality assurance.