This block of examples consists of spoken digit strings (e.g. as if reading a telephone number), but each example has been subjected to a range of modifications: It has been filtered by four different channel characteristics (f1..f4); it has had three different kinds of noise (n0, n1, n2) added at two levels (nXL, nXH), and it has had two reverberation characteristics (r1, r2) added also at two direct-to-reverberant levels (rXL, rXH).
(The same set of modifications is also applied to the sentence examples)
Each row in the following table corresponds to a single base sample, with the differently corrupted versions arrayed across the columns.
The spoken digit strings are from the TIDIGITS corpus of several thousand continuous digits utterances. The background noises are excerpted from the Aurora noisy digits evaluation, and the reverberation characteristics are from a couple of random sources.