Tuning DSP Parameters (simple trick to improve accuracy, decrease inference time and decrease memory usage)

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Recycle Bin that sorts rubbish based on the sound of collision using Edge AI audio classification.

samuel-alexanderSamuel Alexander 10/09/2023 at 13:100 Comments

In the Edge Impulse DSP (Digital Signal Processing) parameter tuning we can see the Mel energy levels and FFT Bin weighting. From here we can adjust and optimize the parameters to lower the memory usage and processing time (DSP + Inference time). 

The first step is to adjust the noise floor until the highest Mel energy (red) and lowest Mel energy (blue) becomes visible. I have settled with -35 dB (Initially it was set to -55 dB.

From the diagram above we can see that there is not much pattern under 240 Hz frequency for all four different objects. So we can set the Lowest band edge to 240 Hz.

The benefit of doing this is we can eliminate wind noise almost entirely because the signal energy of wind noise is typically concentrated below 300 Hz. Setting the lowest band edge to 240 Hz will also filter out Humming noises before we use the data for inferencing.