diff --git a/pyedflib/edfreader.py b/pyedflib/edfreader.py
index 2730f62..799132e 100644
--- a/pyedflib/edfreader.py
+++ b/pyedflib/edfreader.py
@@ -370,11 +370,10 @@ def getStartdatetime(self):
 
     def getBirthdate(self, string=True):
         """
-        Returns the birthdate as string object
+        Returns the birthdate as a string.
 
         Parameters
         ----------
-        None
 
         Examples
         --------
@@ -393,7 +392,9 @@ def getBirthdate(self, string=True):
 
     def getSampleFrequencies(self):
         """
-        Returns  samplefrequencies of all signals.
+        Returns the number of samples for all channels.
+
+        The effective sample frequency is samplefrequency / duration.
 
         Parameters
         ----------
@@ -413,7 +414,9 @@ def getSampleFrequencies(self):
 
     def getSampleFrequency(self, chn):
         """
-        Returns the samplefrequency of signal edfsignal.
+        Returns the number of samples in given channel.
+
+        The effective sample frequency is samplefrequency / duration.
 
         Parameters
         ----------