and only now is it occurring to me that i should have graphed differences in percentage, rather than absolute hertz difference. oh well. anyway, that's all, i just thought that it was interesting to look at these differences! more on the math and underlying hardware here https://gbdev.io/pandocs/Audio_Registers.html and i used this table http://www.devrs.com/gb/files/sndtab.html to check my work. the end!