5 Quality under error conditions (UPCM, No IRS), Experiment 2
3GPP46.008Half rate speechPerformance Characterization of the GSM Half Rate speech codecRelease 17TS
A listening-only test was chosen, adopting the Absolute Category Rating (ACR) method.
Subjective tests were carried out by BT (United Kingdom), CSELT (Italy), and DEUTSCHE TELEKOM (Germany). Table 2 reports the results obtained in Experiment 2: each cell shows the difference in terms of equivalent Q values between the candidate and the full rate codec, negative values meaning worse performance than the full rate codec.
Table 2: Results from experiment 2 (UPCM, No IRS)
|
Input Level |
|||
|
Error Pattern |
-12 |
-22 |
-32 |
|
EP0 |
-1,13 |
-2,90 |
-1,70 |
|
EP1 |
-3,72 |
-1,72 |
-1,21 |
|
EP2 |
-1,93 |
-1,79 |
0,69 |
|
EP3 |
0,79 |
1,49 |
3,59 |
NOTE: The figures indicate DQ values in dB, where DQ = QHR – QFR.
In general, the candidate codec performed equally well or slightly worse than the full rate (in one case, at -12 dB relative to Overload point (OVL) in EP1 condition, QHR – QFR exceeded the -3 dB limit).