recorders have a hole four that is smaller than hole five. The immediate difference in fingering is for F (soprano) or B (alto), which on a neo-baroque instrument must be fingered 0 123 4–67. With German fingering, this becomes a simpler 0 123 4 – – –. Unfortunately, however, this makes many other chromatic notes too out of tune to be usable. German fingering became popular in Europe, especially Germany, in the 1930s, but rapidly became obsolete in the 1950s as people began to treat the recorder more seriously, and the limitations of German fingering became more widely appreciated. Recorders with German fingering are today manufactured exclusively for educational purposes. Pitch Modern recorders are most commonly pitched at A=440 Hz, but among serious amateurs and professionals, other pitch standards are often found. For the performance of baroque music, A=415 Hz is the de facto standard, while pre-Baroque music is often performed at A=440 Hz or A=466 Hz. These pitch standards are intended to reflect the broad variation in pitch standards throughout the history of the recorder. In various regions, contexts, and time periods, pitch standards have varied from A=~392 Hz to A=~520 Hz. The pitches A=415 Hz and A=466 Hz, a semitone lower and a semitone higher than A=440 Hz respectively, were chosen because they may be used with harpsichords or chamber organs that transpose up or down a semitone from A=440. These pitch standards allow recorder players to collaborate with other instrumentalists at a pitch other than A=440 Hz. Some recorder makers produce instruments at pitches other than the three standard pitches above, and recorders with interchangeable bodies at different pitches. Acoustics Basic sound production The recorder produces sound in the manner of a whistle or an organ flue pipe. In normal play, the player blows into the windway (B), a narrow channel in the head joint, which directs a stream of air across a gap called the window, at a sharp edge called the labium (C). The air stream alternately travels above and below the labium, exciting standing waves in the bore of the recorder, and producing sound waves that emanate away from the window. Feedback from the resonance of the tube regulates the pitch of the sound. In recorders, as in all woodwind instruments, the air column inside the instrument behaves like a vibrating string, to use a musical analogy, and has multiple modes of vibration. These