Octave mandolin in unison. Alternate tunings exist in which the strings in some courses are tuned to octaves, rather than unisons, but this is more typical of the Irish Bouzouki. Usually, courses of 2 adjacent strings are doubled (tuned to the same pitch). The standard octave mandolin tuning is G2 G2 • D3 D3 • A3 A3 • E4 E4, so the lowest open strings are tuned to the lowest 'G' on the guitar, and the highest strings are tuned to the same 'E' as the highest string of the guitar. This tuning is one octave below the mandolin (or a fourth
Concert pitch D-flat), and are often tuned to match B brass instruments when the two are required to play together. The Stuttgart Conference of 1834 recommended C264 (A440) as the standard pitch based on Scheibler's studies with his Tonometer. For this reason A440 has been referred to as Stuttgart pitch or Scheibler pitch. In 1939, an international conference recommended that the A above middle C be tuned to 440 Hz, now known as "concert pitch". As a technical standard this was taken up by the International Organization for Standardization in 1955 and reaffirmed by them in 1975 as ISO 16. The difference