## 3 Simulations and Measurements
### Effect of the Algorithm on Signal  
The cochleagram of a clean speech from the OLSA corpus (first raw) and two preprocessed speech signals, one of them preprocessed with the OE algorithm [16] (second \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Room**} & **Name in** & \multirow{2}{*}{\(T_{60}\) (s)**} & **Length of \(P\) Frames (s)** & **Main BRIR** & **BRIR for Robustness** & **BRIR of Noise** \\  & **Database** & & & & **Evaluation** & **BRIR of Noise** \\ \hline R1 & VarEcoic & 0.60 & 0.25 & kas\_none\_r00\_az000 & kas\_none\_r00\_az00 & kas\_none\_r00\_az030 \\ R2 & Music Hall & 1.1 & 0.45 & CR3\_BRIR\_L57\_ & CR3\_BRIR\_L5\_ & CR3\_BRIR\_L53 \\  & & & & & & \\  & & & & & & \\  & & & & & & \\ R3 & Seminar Room & 1.5 & 0.6 & CR2\_BRIR\_L54\_ & CR2\_BRIR\_L53 & CR2\_BRIR\_L53 \\  & & & & & & \\  & & & & & & \\ R4 & Church & 5.0 & 1 & air\_binaural\_aul\_ & air\_binaural\_aul\_ & air\_binaural\_aul\_ \\  & & & & & & \\  & & & & & & \\  & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The BRIRs used for the optimization and subjective evaluation. The room names in the database, reverberation times, the length of \(P\) frames, and selected BRIRs are mentioned. raw) and another one preprocessed by the proposed algorithm (third raw), are depicted in Figure 3a.The weights are calculated for room R4. It can be seen that the preprocessing of OE and the proposed algorithm causes a high-pass filter effect on the speech, which is caused by the fact that both enhancement algorithms reduced the amplitude of speech portions with a high and constant energy over time or those which were exposed to a longer \(T_{60}\) (yellow ovals in the left panels). It can be seen that this attenuation is stronger for the proposed method in comparison to the OE. Because of the importance of onsets for intelligibility, and in accordance with Equation (12), onsets are more strongly weighted in the proposed method. The other steady portions, on the other hand, are allowed to be attenuated more in order to minimize the defined cost function. The signals of Figure 3a are now convolved with the left ear of BRIR in room R4 and their cochleagrams are plotted in. The cochleagram of reverbed unprocessed, reverbed preprocessed by OE, and reverbed preprocessed by the proposed algorithm are shown in the first, second, and third panels of Figure 3b, respectively. Besides the onset enhancement and high-pass filtering effect of the proposed approach, the effect of the frame attenuations can be compared with the two other reverbed signals. The effect can be seen in the longer silent gap of the clean speech around second 1 (yellow rectangles in the left panels). It can be seen that in the third panel belonging to the proposed method, there is a low amount of energy leakage from previous frames into the silent gap in comparison to the unprocessed and OE-preprocessed reverbed signals. A similar effect can be seen in second 1.6. This effect can potentially contribute to higher speech intelligibility due to the reduced overlap masking of preceding speech segments. Figure 3: (**a**) The cochleagram of clean speech and two preprocessed speech signals are shown. The first-row panel shows the unprocessed speech sentence. Second-row panel shows a preprocessed speech sentence using OE algorithm and the third-row panel shows the preprocessed speech using the proposed algorithm obtained for room R4. The yellow ovals show the difference between the unprocessed signal and two enhanced signals. The preprocessing of OE and the proposed algorithm has a high-pass filter effect on the speech. ; (**b**) The cochleagram of three reverbed signals in room R4 are shown. The first-row panel shows the unprocessed clean sentence. In the first-raw panel, a reverbed unprocessed speech sentence is depicted. The second-row and third-row panels show a reverbed preprocessed speech sentence using OE algorithm and the proposed algorithm respectively. Yellow rectangles show the effect of the frame attenuations in the OE and proposed approaches.