Tratamiento Digital de Voz Prof. Luis A. Hernández Gómez ftp.gaps.ssr.upm.es/pub/TDV/DOC/ Tema2c.ppt Dpto. Señales, Sistemas y Radiocomunicaciones

Agenda Perceptual evaluation of Speech Quality Traditional evaluation of Speech Quality A new approach to evaluation of Speech Quality Perceptual Evaluation of Speech Quality within ITU-T

The idea To simulate the sound perception of subjects in real-life situations To have a objective technique based on a perceptual model that will reveal the same MOS score as that of Listening Test What is MOS? Methods and procedures for conducting subjective evaluation of transmission quality (ITU -T Rec. 800) Quality of speech based on Listening Tests A new approach to evaluation of Speech Quality

Objective techniques used for predicting subjective test scores PSQM (Perceptual Speech Quality Measure) PSQM+ (ITU -T Rec. 861) PESQ (Perceptual Evaluation of Speech Quality) (ITU -T Rec. 862) and others like MNB, PAMS, TOSQA, PACE, VQI and PESQM. About PSQM, PSQM+, PESQ For jugging the listening and talking quality of Telephone band speech signals ( Hz) Signals of the input and output of the device under test are mapped onto a psychophysical representation that match as close as possible the internal representation inside our head A new approach to evaluation of Speech Quality

Agenda Perceptual evaluation of Speech Quality Traditional evaluation of Speech Quality A new approach to evaluation of Speech Quality Perceptual Evaluation of Speech Quality within ITU-T

Generic perceptual measurement algorithm Perceptual Model Feature- Extractor Test Perceptual Model Reference Cognitive Model Quality measure ImpairmentGrade Excellent5 Good4 Fair3 Poor2 Bad1 Perceptual Model Is a model of the Human Ear Cognitive Model Is a model of the judgement behaviour of the test subject

Basic model of PSQM & PSQM+ algorithm Perceptual Model Internal representation of the reference signal Test Perceptual Model Reference Cognitive Model Quality measure Difference in internal representation Internal representation of the test signal Improvements in PSQM+ Time alignment: variable delay, frame repeats Weight of distortion: time clipping, time frequency distortion Improvements in PSQM+ Time alignment: variable delay, frame repeats Weight of distortion: time clipping, time frequency distortion

Basic model of PESQ algorithm Auditory transform Degraded Level align Reference Cognitive Modelling Quality measure Input filter Auditory transform Disturbance processing Identify bad intervals Time align and equalise Level align Input filter Next step is PESQM Assessment of Handset on a perceptual basis using HATS Covering echo and Sidetone Next step is PESQM Assessment of Handset on a perceptual basis using HATS Covering echo and Sidetone

Perceptual measurement algorithms - roadmap PSQM P.861, 1996 Intrusive Narrowband Speech Quality PSQM PESQ P.862, 1996 PESQM 2001,2002 Conversational Quality P3SQM 2001,2002 Echo and Acoustical measurement Non-Intrusive Narrowband Speech Quality Wideband Audio Video measurement PEAQ BS1387, 1996 PEAQ Acoustical PESQ extension Single-ended Voice Quality PEVQ Wideband Voice Quality Audiovisual Quality