28
OWNER’S MANUAL
APM /
Calculation of the TMD score
The values of
total distortion
(%) and
total alteration
(dB) are determined respectively by the weighted average
of the
partial distortion
indexes (high, medium, low range) and by the weighted average of the
partial alterations
according to the weights of the MSQR.
The software performs an appropriate rounding to make the fluctuations of the values stable and significant and
derives the scores by using a logarithmic scale calibrated to have a real correspondence with the perception of
quality and to make the MSQR contest engaging.
• 120 (MAX)
corresponds to a distortion / alteration equal or less than 1%/ 1dB respectively
• 70 (min)
corresponds to a distortion / alteration equal or higher than 15% / 15dB respectively
• 100 (Soglia)
corresponds to a distortion / alteration of respectively 3% / 3dB, considered as an acceptability
threshold for a real system perceived as good.
The software favors distortion / alteration values between
3% / 3 dB
and
1% / 1dB
, where it is possible to earn up
to 20 points and the perception of quality linked to the TMD indexes finds an excellent correspondence with human
perception.
6