The error rate for congas is relatively low, but this can be attributed to the fact that congas mainly appear in the test and training data within rhythms explicitly using that drum type (a rhythm simply featuring perhaps two conga drums). Hence noise interference from other kit sounds will be low.
Snares are slightly higher in error rate than congas, but conversely they almost always appear within the noise of a full drum kit.
Lastly there is the much larger error in the tom drums. Toms span the greatest pitch range of all the drum types here, and very often have a large amount of low spectral energy. Thus in many instances they have probably been classified as kicks. In addition toms of higher pitches that appear as tom/hat combinations will sound very similar to snare drums (a snare is like a tom with an added amount of higher frequency energy, similar to a tom/hat combination).
6.4. Post classification
Due to the time constraints of the project, a thorough investigation of the post classification algorithms was not possible. This is mainly because of the time it takes to manually listen to each break in the training set and label all the soft hits and pitch groups.