    /// - Parameters:
    ///   - letter: The letter of the note
    ///   - octave: The octave of the note
    /// - Throws: An error if the rest of the components cannot be calculated
    public init(letter: Letter, octave: Int) throws {
        self.letter    = letter
        self.octave    = octave
        index          = try NoteCalculator.index(forLetter: letter, octave: octave)
        frequency      = try NoteCalculator.frequency(forIndex: index)
        wave           = try AcousticWave(frequency: frequency)
    }
