Don't people's voices generally go up in pitch when they scream in terror?
So would Zimmerman's.
If Martin's voice was deeper, how would the scream being high pitched exclude Zimmerman?
No one actually said the voice calling for help sounded high pitched or youthful until days or weeks after the shooting.
Mary Cutcher and Selma Mora told Serino they didn't hear any words.
W-18 told 911 she saw two 'men' wrestling, and then one of 'men' started calling for help. She said the same to Serino that night.
Austin (W-14) told 911, and Serino a few days later, that the man on the ground was the screamer. He is supposed to have told a journalist that he had changed his mind and thought Trayvon was the screamer, but that's not mentioned in the summary of his SAO interview (p. 33 of the July 12,
284 page release).
Cutcher and Mora were paraded on TV, saying they thought a 'little boy' was crying, and not mentioning that they didn't even hear the calls for help. W-18 went on CNN, in the dark with a voice distorter, and said she thought the 'young boy' was calling for help.
All this has given much of the public the impression that up to four on-scene witnesses support Martin as the screamer, on the grounds of the voice being youthfully high-pitched.