Its cries are human.
3 seconds sound clip from the Island of Lost Souls (1932) movie soundboard.
You can hear this line at 00:32:46 in the Blu-ray version of the movie.
Quote context
[...]
- My work, my discoveries. Mine alone.
- With these I have wiped out hundreds of thousands of years of evolution.
- From the lower animals, I have made... Well, see for yourself.
- You're convinced that this thing on the table isn't human.
- You know what it is that I began with? An animal.
- An animal? Like those in the cages outside?
- Then those - those creatures out in the jungle?
- They were made from animals?
- Yes.
- Was this thing, this poor, tortured creature...?
[...]