Cross tuning if played in regular tuning, while the sounded pitch is altered. Cross tuning is commonly used on the fiddle in folk music of Appalachia, the southern United States and Scandinavia. The fiddle may be re-tuned in any number of ways in these musical idioms, but there are two common re-tunings. While the standard tuning for open strings of the violin is GDAE—with the G being the tuning of the lowest-pitched string and the E being the tuning for the highest-pitched string—fiddlers playing tunes in the key of D major sometimes employ a tuning of ADAE. In this tuning the open
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