hertz

[Function]
  `(``hertz` freq {keyword value}*`)`

Returns the Hertz value of freq, which can be a note name, key number, Hertz value or list of the same.

`hertz` supports the following keyword arguments:

`:hz` boolean
  If true then a numerical freq is interpreted as a Hertz value rather than as a key number.
`:in` tuning
  The tuning to return the Hertz value from. The default value is `*scale*`.
`:through` { tuning | mode}
  Filters freq through tuning or mode and returns the Hertz value of the closest Hertz values.

#### Examples:

Example 1. Converting notes and key numbers to Hertz.

    (hertz 'c4)
    ⇒ 261.625
    (hertz '(a4 c5 e))
    ⇒ (440.0 523.2511 659.2552)
    (hertz 0)
    ⇒ 8.175
    (hertz '(69 69.5 70))
    ⇒ (440.0 452.892 466.163)

Example 2. Tunings and Hertz.

    ;;; define a scale whose steps are harmonics 8-16.
    (define harms
      (new tuning :ratios (loop for i from 8 to 16 collect (/ i 8))
           :lowest (hertz 'c0)))

    ;; middle c octave
    (hertz (loop for k from 32 to 40 collect k) :in harms)
    ⇒ (261.625 294.328 327.031 359.735 392.438 425.14 457.844 490.54 523.25)

#### See Also:

- `invert` [Function]
- `keynum` [Function]
- `note` [Function]
- `note-accidental` [Function]
- `note-name` [Function]
- `octave-number` [Function]
- `pitch-class` [Function]
- `prime-form` [Function]
- `scale-max` [Function]
- `scale-min` [Function]
- `scale-mod` [Function]
- `scale-order` [Function]
- `scale<` [Function]
- `scale<=` [Function]
- `scale=` [Function]
- `scale>` [Function]
- `scale>=` [Function]
- `transpose` [Function]