There is film of McKinley's last speech made at the Buffalo World's Fair in Sept of 1901. There is sadly, no recordings of it. I have seen in many films in which they say the recording is McKinley's voice, but I am not at all in agreement. I hear the voices of Harry and Len Spencer, William Hooley, and Arthur Collins. There is a recording playing on the internet that says it is a campaign recording by McKinley. I dare say not.
First the recording of cheers would have been next to impossible, secondly and more important the man speaking has no regional accent. McKinley was from Ohio and was known for a bit of a Ohio styled accent. His wife always called him the "May-jah" That is for Major. Listen to any person from that area before the effects of TV and cable and you hear what I mean by regional accents. Just listen to a recording of Warren G Harding, or William Howard Taft who were from Ohio as well and have that regional dialect.
As far as I can tell there are no existent recordings of McKinley's voice and there is little info that he made any recordings either.
McKinley's last speech is on record. It was performed by Len and Harry Spencer. As well as William Hooley. I have a copy of Len Spencer doing it in 1902.
The recording that is on youtube a lot of McKinley's campaign speech sounds very much like Arthur Collins. It is not McKinley! Any recording on youtube of McKinley is fake.
Also the campaign recording for Grover Cleveland on youtube is not Cleveland either. It sounds like one of the Spencer brothers. It is not Grover Cleveland! Any recording of Cleveland on youtube is fake.
The earliest recording of a President was a Bettini cylinder of former President Benj. Harrison in 1901. The rest are fakes.
So there is film of McKinley, but nothing recorded of what his voice was like. What a loss.