Deriving notes from given (fundamental) frequencies.
noteFromFF(x, diapason = 440, roundshift = 0)An integer representing the (rounded) difference in halftones from diapason a,
i.e. indicating the note that corresponds to fundamental frequency x given the value of diapason.
For example: 0 indicates diapason a, 3: c', 12: a', ...
Fundamental frequency.
Frequency of diapason a, default is 440 (Hertz).
Shift that indicates from here to round to the next integer (note).
The default (0) is “classical” rounding as described in round.
A higher value means that roundshift is added to the calculated real note value
before rounding to an integer. This is useful if it is unclear that some instruments really
shift the note in the center between two theoretical frequencies.
Example: if x = 452 and diapason = 440, the internally calculated
real value of 0.46583 is rounded to 0,
but for roundshift = 0.1 we get 0.56583 and it is rounded to note 1.
Uwe Ligges ligges@statistik.tu-dortmund.de
The formula used is simply round(12 * log(x / diapason, 2) + roundshift).
FF, periodogram, and tuneR for a very complete example.