[CC] docstring update

Author: wantysal

mosqito/sound_level_meter/noct_spectrum/_filter_bandwidth.py

@@ -30,6 +30,11 @@ def _filter_bandwidth(fc, n=3, N=3):
     alpha : numpy.ndarray
         Ratio of the upper and lower band-edge frequencies to the mid-band
         frequency
+    f1 : float
+        Lower frequency of the band in Hz
+    f2 : float
+        Upper frequency of the band in Hz
+
     """
 
     """