# Cross-Corpus Training Strategy for Speech Emotion Recognition Using Self-Supervised Representations
## 5 Experiments
### Experimental Framework Description  
Experiments were conducted in a five-fold cross-validation scheme, for a multi-class classification framework with four classes consisting of the emotions: neutral, happiness, sadness, and anger. To ensure a robust and reliable evaluation, 10% of the training partitions were randomly set aside as a development set at each epoch. The final results were obtained from the test set of the iteration that yielded the best development outcome. The test set was carefully constructed to ensure a balanced representation of gender. It comprised one-fifth of the speakers, and the distribution of male and female speakers was equal.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**STEP**} & \multicolumn{2}{c}{**EmoDb**} & \multicolumn{2}{c}{**RAVDESS**} \\ \cline{2-5}  & **TRAIN** & **TEST** & **TRAIN** & **TEST** \\ \hline \multirow{2}{*}{0} & \multirow{2}{*}{IEMOCAP} & 2 speakers of & \multirow{2}{*}{IEMOCAP} & 4 speakers \\  & & EmoDb & & of RAVDESS \\ \hline \multirow{3}{*}{1} & IEMOCAP + 3 min & \multirow{3}{*}{2 speakers of EmoDb} & IEMOCAP + 7 min & \multirow{3}{*}{4 speakers} \\  & EmoDb & & RAVDESS & & of RAVDESS \\ \cline{1-1}  & (2 speakers) & & (4 speakers) & & \\ \hline \multirow{3}{*}{2} & IEMOCAP + 6 min & \multirow{3}{*}{2 speakers of EmoDb} & IEMOCAP + 14 min RAVDESS & \multirow{3}{*}{4 speakers} \\  & (4 speakers) & & (8 speakers) & & \\ \hline \multirow{3}{*}{3} & IEMOCAP + 9 min & \multirow{3}{*}{2 speakers of EmoDb} & IEMOCAP + 21 min RAVDESS & \multirow{3}{*}{4 speakers} \\  & EmoDb & & (12 speakers) & & \\ \cline{1-1}  & (8 speakers) & & (16 speakers) & & \\ \hline \multirow{3}{*}{4} & IEMOCAP + & \multirow{3}{*}{2 speakers of EmoDb} & IEMOCAP + 21 min RAVDESS & \multirow{3}{*}{4 speakers} \\  & (8 speakers) & & (12 speakers) & & \\ \hline \multirow{3}{*}{4} & IEMOCAP + & \multirow{3}{*}{2 speakers of EmoDb} & IEMOCAP + 28 min RAVDESS & \multirow{3}{*}{4 speakers} \\  & & & (16 speakers) & & \\ \hline \multirow{3}{*}{5} & \multirow{3}{*}{} & IEMOCAP + & \multirow{3}{*}{4 speakers} \\  & & & (20 speakers) & & \\ \hline \hline \end{tabular}
\end{table}
Table 4: Train and test databases used in experiment 3: role of in-domain data in the training set. Train and test sets are always gender-balanced; audio and speakers in the train set are not included in the test set.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{**MATCHED TRAIN**} & \multicolumn{1}{c}{**EXTENDED TRAIN**} & \multicolumn{1}{c}{**TEST**} \\ \hline \hline \multirow{4}{*}{IEMOCAP} & EmoDb & \multirow{4}{*}{IEMOCAP} \\  & RAVDESS & \multirow{4}{*}{IEMOCAP} \\  & CREMA-D & & \\ \cline{1-1}  & IEMOCAP & \\ \hline \multirow{4}{*}{CREMA-D} & EmoDb & \multirow{4}{*}{CREMA-D} \\  & RAVDESS & & \\ \cline{1-1}  & CREMA-D & & \\ \cline{1-1}  & IEMOCAP & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Train and test databases used in experiment 2: effect of dataset size and diversity in cross-corpus strategy for training. Audio and speakers in the train set are not included in the test set.  
For the IEMOCAP dataset, the test set consisted of one recording session involving a spontaneous conversation between a male and a female speaker. This experimental design aimed to provide a comprehensive evaluation of the model's performance across multiple emotion categories while maintaining a fair and equitable representation of speakers and gender in the test set.