CTU Events

«  October  2016  »
Mo Tu We Th Fr Sa Su
          1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30

Back to calendar

Detecting coding artifacts in foreign language items

27 Oct 2016   10:00

The lecture on research methods and results of detecting coding artifacts in foreign language items used during subjective testing of speech quality.

The lecture will be given by Dr. rer. nat. Nadja Schinkel-Bielefeld from the Fraunhofer Institute for Integrated Circuits IIS.


The quality of perceptual audio codecs is commonly evaluated using listening tests. For audio signals of intermediate quality the test of choice is a multi-stimulus test with hidden reference and anchor (MUSHRA). As such tests often are performed jointly by labs all over the world listeners inevitably also rate items in foreign languages which they might not even understand. However, so far it is not well understood to what extent the lack of understanding or familiarity to the phonemes of a language helps or hinders the listener in detecting artifacts in these tests.

To analyze this question we performed a study with Mandarin Chinese and German listeners who rated Chinese and German audio material. Overall we found no significant effect of the language on the rating of the stimuli. However, when comparing the two listener groups, listeners spent more time and compared more often between the different conditions, when listening to the foreign language audio material. This effect vanished when lower bit rates were used and artifacts were easier to detect.

In contrast, in a study with German sentences and German sounding nonsense sentences, in comparison to non-German listeners, German listeners tend to spend more time on the grammatical German sentences than on the pseudo German sentences and also tend to rate German sentences more critical.

This possibly indicates that listeners care more for German than for non-understandable but similar sounding pseudo German. However, when rating actual foreign languages this effect may be masked by the listener?s effort to compensate for any difficulties in rating the unfamiliar sounding language resulting in longer listening times for the foreign language.

Contact person
doc. Ing. Jan Holub, Ph.D., jan.holub@fel.cvut.cz