sub-contra

[English] Under the Helmholtz Octave Designation System, a name applied to the octave which extends from C0 three octaves below the bass clef staff to B0 two octaves below the bass clef staff.

British Dictionary definitions for contra- contra- prefix. against; contrary; opposing; contrasting: contraceptive; contradistinction. (in music) pitched below: contrabass.

Scientific pitch notation (SPN), also known as American standard pitch notation (ASPN) and international pitch notation (IPN), is a method of specifying musical pitch by combining a musical note name (with accidental if needed) and a number identifying the pitch's octave.

The octaves are labeled from lowest to highest, beginning with 0 and continuing in ascending numerical order (1, 2, etc.). A piano keyboard primarily uses the ASPN octave designations 1 through 7, although small portions of octaves 0 and 8 are included.

The terms for the instrument among classical performers are contrabass (which comes from the instrument's Italian name, contrabbasso), string bass (to distinguish it from brass bass instruments in a concert band, such as tubas), or simply bass.

A subcontractor is a person or company that has a contract to do part of a job which another company is responsible for.

A major example of a contra account is an allowance for doubtful accounts. This contra asset reduces the balance of gross accounts receivable by an estimate of how many receivables will go uncollected.

Various music dictionaries that I have at hand agree that the prefix “contra-” means “lower than,” but do not specify an octave lower, and most use contralto voice as an example.

There are only seven note names (A, B, C, D, E, F, G), and each line or space on a staff will correspond with one of those note names. To get all twelve pitches using only the seven note names, we allow any of these notes to be sharp, flat, or natural. Look at the notes on a keyboard.

Western music typically uses 12 notes – C, D, E, F, G, A and B, plus five flats and equivalent sharps in between, which are: C sharp/D flat (they're the same note, just named differently depending on what key signature is being used), D sharp/E flat, F sharp/G flat, G sharp/A flat and A sharp/B flat.

The word "octave" comes from a Latin root meaning "eight". It seems an odd name for a frequency that is two times, not eight times, higher. The octave was named by musicians who were more interested in how octaves are divided into scales, than in how their frequencies are related.

The next pitch is called the octave because it's the eighth note (just as an octopus has eight legs). More than a thousand years ago the letters of the Roman alphabet were adopted to refer to these, and since there were only seven the letters ran A, B, C, D, E, F, G.