diff --git a/AUTHORS b/AUTHORS
index 8d31ea2..eeed788 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -92,4 +92,7 @@ Chendi Luo
     github: Creonalia
 
 Daniel Lefevre
-    gitHub: dplefevre
\ No newline at end of file
+    gitHub: dplefevre
+
+Grzegorz Kotfis
+    github: gkotfis
\ No newline at end of file
diff --git a/pydub/scipy_effects.py b/pydub/scipy_effects.py
index 177c4ff..abab2b4 100644
--- a/pydub/scipy_effects.py
+++ b/pydub/scipy_effects.py
@@ -76,100 +76,100 @@ def _eq(seg, focus_freq, bandwidth=100, mode="peak", gain_dB=0, order=2):
     Returns:
         Equalized/Filtered AudioSegment
     """
-	filt_mode = ["peak", "low_shelf", "high_shelf"]
-	if mode not in filt_mode:
-		raise ValueError("Incorrect Mode Selection")
-		
-	if gain_dB >= 0:
-		if mode == "peak":
-			sec = band_pass_filter(seg, focus_freq - bandwidth/2, focus_freq + bandwidth/2, order = order)
-			seg = seg.overlay(sec - (3 - gain_dB))
-			return seg
-		
-		if mode == "low_shelf":
-			sec = low_pass_filter(seg, focus_freq, order=order)
-			seg = seg.overlay(sec - (3 - gain_dB))
-			return seg
-		
-		if mode == "high_shelf":
-			sec = high_pass_filter(seg, focus_freq, order=order)
-			seg = seg.overlay(sec - (3 - gain_dB))
-			return seg
-		
-	if gain_dB < 0:
-		if mode == "peak":
-			sec = high_pass_filter(seg, focus_freq - bandwidth/2, order=order)
-			seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
-			sec = low_pass_filter(seg, focus_freq + bandwidth/2, order=order)
-			seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
-			return seg
-		
-		if mode == "low_shelf":
-			sec = high_pass_filter(seg, focus_freq, order=order)
-			seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
-			return seg
-		
-		if mode=="high_shelf":
-			sec=low_pass_filter(seg, focus_freq, order=order)
-			seg=seg.overlay(sec - (3 + gain_dB)) +gain_dB
-			return seg
-		
+    filt_mode = ["peak", "low_shelf", "high_shelf"]
+    if mode not in filt_mode:
+        raise ValueError("Incorrect Mode Selection")
+        
+    if gain_dB >= 0:
+        if mode == "peak":
+            sec = band_pass_filter(seg, focus_freq - bandwidth/2, focus_freq + bandwidth/2, order = order)
+            seg = seg.overlay(sec - (3 - gain_dB))
+            return seg
+        
+        if mode == "low_shelf":
+            sec = low_pass_filter(seg, focus_freq, order=order)
+            seg = seg.overlay(sec - (3 - gain_dB))
+            return seg
+        
+        if mode == "high_shelf":
+            sec = high_pass_filter(seg, focus_freq, order=order)
+            seg = seg.overlay(sec - (3 - gain_dB))
+            return seg
+        
+    if gain_dB < 0:
+        if mode == "peak":
+            sec = high_pass_filter(seg, focus_freq - bandwidth/2, order=order)
+            seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
+            sec = low_pass_filter(seg, focus_freq + bandwidth/2, order=order)
+            seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
+            return seg
+        
+        if mode == "low_shelf":
+            sec = high_pass_filter(seg, focus_freq, order=order)
+            seg = seg.overlay(sec - (3 + gain_dB)) + gain_dB
+            return seg
+        
+        if mode=="high_shelf":
+            sec=low_pass_filter(seg, focus_freq, order=order)
+            seg=seg.overlay(sec - (3 + gain_dB)) +gain_dB
+            return seg
+        
 
 @register_pydub_effect
 def eq(seg, focus_freq, bandwidth=100, channel_mode="L+R", filter_mode="peak", gain_dB=0, order=2):
-	"""
-	Args:
-		focus_freq - middle frequency or known frequency of band (in Hz)
-		bandwidth - range of the equalizer band
-		channel_mode - Select Channels to be affected by the filter.
-			L+R - Standard Stereo Filter
-			L - Only Left Channel is Filtered
-			R - Only Right Channel is Filtered
-			M+S - Blumlien Stereo Filter(Mid-Side)
-			M - Only Mid Channel is Filtered
-			S - Only Side Channel is Filtered
-			Mono Audio Segments are completely filtered.
-		filter_mode - Mode of Equalization(Peak/Notch(Bell Curve),High Shelf, Low Shelf)
-		order - Rolloff factor(1 - 6dB/Octave 2 - 12dB/Octave)
-	
-	Returns:
-		Equalized/Filtered AudioSegment
     """
-	filt_mode = ["L+R", "M+S", "L", "R", "M", "S"]
-	if mode not in filt_mode:
-		raise ValueError("Incorrect Channel Mode Selection")
-		
-	if seg.channels == 1:
-		return _eq(seg, focus_freq, bandwidth, filter_mode, gain_dB, order)
-		
-	if channel_mode == "L+R":
-		return _eq(seg, focus_freq, bandwidth, filter_mode, gain_dB, order)
-		
-	if channel_mode == "L":
-		seg = seg.split_to_mono()
-		seg = [_eq(seg[0], focus_freq, bandwidth, filter_mode, gain_dB, order), seg[1]]
-		return AudioSegment.from_mono_audio_segements(seg[0], seg[1])
-		
-	if channel_mode == "R":
-		seg = seg.split_to_mono()
-		seg = [seg[0], _eq(seg[1], focus_freq, bandwidth, filter_mode, gain_dB, order)]
-		return AudioSegment.from_mono_audio_segements(seg[0], seg[1])
-		
-	if channel_mode == "M+S":
-		seg = stereo_to_ms(seg)
-		seg = _eq(seg, focus_freq, bandwidth, filter_mode, gain_dB, order)
-		return ms_to_stereo(seg)
-		
-	if channel_mode == "M":
-		seg = stereo_to_ms(seg).split_to_mono()
-		seg = [_eq(seg[0], focus_freq, bandwidth, filter_mode, gain_dB, order), seg[1]]
-		seg = AudioSegment.from_mono_audio_segements(seg[0], seg[1])
-		return ms_to_stereo(seg)
-		
-	if channel_mode == "S":
-		seg = stereo_to_ms(seg).split_to_mono()
-		seg = [seg[0], _eq(seg[1], focus_freq, bandwidth, filter_mode, gain_dB, order)]
-		seg = AudioSegment.from_mono_audio_segements(seg[0], seg[1])
-		return ms_to_stereo(seg)
-		
-	
+    Args:
+        focus_freq - middle frequency or known frequency of band (in Hz)
+        bandwidth - range of the equalizer band
+        channel_mode - Select Channels to be affected by the filter.
+            L+R - Standard Stereo Filter
+            L - Only Left Channel is Filtered
+            R - Only Right Channel is Filtered
+            M+S - Blumlien Stereo Filter(Mid-Side)
+            M - Only Mid Channel is Filtered
+            S - Only Side Channel is Filtered
+            Mono Audio Segments are completely filtered.
+        filter_mode - Mode of Equalization(Peak/Notch(Bell Curve),High Shelf, Low Shelf)
+        order - Rolloff factor(1 - 6dB/Octave 2 - 12dB/Octave)
+    
+    Returns:
+        Equalized/Filtered AudioSegment
+    """
+    channel_modes = ["L+R", "M+S", "L", "R", "M", "S"]
+    if channel_mode not in channel_modes:
+        raise ValueError("Incorrect Channel Mode Selection")
+        
+    if seg.channels == 1:
+        return _eq(seg, focus_freq, bandwidth, filter_mode, gain_dB, order)
+        
+    if channel_mode == "L+R":
+        return _eq(seg, focus_freq, bandwidth, filter_mode, gain_dB, order)
+        
+    if channel_mode == "L":
+        seg = seg.split_to_mono()
+        seg = [_eq(seg[0], focus_freq, bandwidth, filter_mode, gain_dB, order), seg[1]]
+        return AudioSegment.from_mono_audio_segements(seg[0], seg[1])
+        
+    if channel_mode == "R":
+        seg = seg.split_to_mono()
+        seg = [seg[0], _eq(seg[1], focus_freq, bandwidth, filter_mode, gain_dB, order)]
+        return AudioSegment.from_mono_audio_segements(seg[0], seg[1])
+        
+    if channel_mode == "M+S":
+        seg = stereo_to_ms(seg)
+        seg = _eq(seg, focus_freq, bandwidth, filter_mode, gain_dB, order)
+        return ms_to_stereo(seg)
+        
+    if channel_mode == "M":
+        seg = stereo_to_ms(seg).split_to_mono()
+        seg = [_eq(seg[0], focus_freq, bandwidth, filter_mode, gain_dB, order), seg[1]]
+        seg = AudioSegment.from_mono_audio_segements(seg[0], seg[1])
+        return ms_to_stereo(seg)
+        
+    if channel_mode == "S":
+        seg = stereo_to_ms(seg).split_to_mono()
+        seg = [seg[0], _eq(seg[1], focus_freq, bandwidth, filter_mode, gain_dB, order)]
+        seg = AudioSegment.from_mono_audio_segements(seg[0], seg[1])
+        return ms_to_stereo(seg)
+
+