189746
In 1897 , Stern invented the tone variator , allowing him to research human perception of sound in an unprecedented way .
 person: Stern
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Stern 
Answer:
 person: Stern