https://au.mathworks.com/help/deeplearning/ref/nnet.cnn.layer.averagepooling1dlayer.html
AveragePooling1DLayer - 1-D average pooling layer - MATLAB
A 1-D average pooling layer performs downsampling by dividing the input into 1-D pooling regions, then computing the average of each region.
averagepoolinglayermatlab