filters = []
low_cutoff_freqs = [500, 1000, 1500]
high_cutoff_freqs = [1000, 1500, 2000]
for low, high in zip(low_cutoff_freqs, high_cutoff_freqs):
    filters.append(slab.Filter.band(frequency=(low, high), kind='bp'))
fbank = slab.Filter(filters)  # put the list into a single filter object
sound_filt = fbank.apply(sound)  # apply each filter to a copy of sound
# plot the spectra, each color represents one channel of the filtered sound
_, ax = plt.subplots(1)
sound_filt.spectrum(axis=ax, show=False)
ax.set_xlim(100, 5000)
plt.show()