What is SQUAD-HD

SQUAD-HD

SQuad-HD is SwissQual’s proprietary full-reference quality assessment algorithm for HD voice channels. It makes use of pre-processed speech samples transmitted over the channel under test to determine the degradation from the channel itself. On the receiving end the degradation impact is determined by comparing the degraded sample to the original test sample.   SQuad-HD consists of three key elements:

a) a pre-processing unit that adjusts the reference and coded samples in the time and level-domains;
b) a psychoacoustic model is that used to reduce both samples to the perceptually relevant features; and
c) an opinion unit which evaluates the perceptual difference between reference and degraded samples and outputs the result as a MOS objective value.

The output quality scale is mapped onto the metrics of the “overall listening quality” and “single talk conditions” by using the Absolute Category Rating (ACR) opinion scale per ITU-T’s recommendation P.800.1. For each speech clip evaluated, SQuad-HD provides detailed information such as:

MOS rating
Temporal clipping
Interruptions / Impulsive noise
Frequency shift
Delay spread & deviation
Active speech level
Noise level
Static SNR
Channel gain pattern
Channel frequency response