The double bass is the largest and lowest-pitched bowed string instrument in the modern symphony orchestra. It is a transposing instrument and is typically notated one octave higher than sounding to avoid excessive ledger lines. The double bass is the only modern bowed string instrument that is tuned in fourths (like a viol), rather than fifths, with strings usually tuned to E1, A1, D2 and G2. The instrument's exact lineage is still a matter of some debate, with scholars divided on whether the bass is derived from the viol or the violin family.