Note that your loop isn't needed. It's simply:
tempo_drums_round = round(tempo_drums); %Rounding the values
tempoModedrums = mode(tempo_drums_round,2); %Most used value for tempo for drums
t_low = tempoModedrums - tempoModedrums / 10;
t_high = tempoModedrums + tempoModedrums / 10;
t_range = [t_low, t_high];
which could be coded even more simply as:
tempo_drums_round = round(tempo_drums); %Rounding the values
tempoModedrums = mode(tempo_drums_round,2); %Most used value for tempo for drums
t_range = tempoModedrums + tempoModedrums ./ [-10, 10]; %subtract (1st column) and add (2nd column) tempoModedrums / 10 to tempoModedrums
Considering that in each row, you may have a different number of subjects within your band, what do you want as output? It can be a matrix, it could be a cell array.
