Technical information

that the Middle C of a piano has a frequency of 261 hertz, we are actually talking
about its fundamental frequency, not that of the harmonics without which a piano
note would have no distinguishing character.
G
GB Gigabyte See gigabyte.
Gigahertz A measure of frequency: 1,000,000,000 hertz.
GHz Gigahertz See gigahertz.
Gigabyte A measure of memory storage, a gigabyte equals (i.e. 1,024 x 1,024 x
1,024 or 2
30
) bytes, 1,048,576 (i.e. 1,024 x 1,024 or 2
20
) kilobytes or 1,024
megabytes. However, if used as a measure of hard disk storage, the 'giga' prefix
normally means a round billion.
Group The major divisions for content on a DVD Audio disc. Typically the surround
sound mix is in a different group to the stereo mix, while bonus video clips are in a
separate group. This is the equivalent of a Title on a DVD Video. A Group is
normally subdivided into Tracks.
H
Harmonic A tone the frequency of which is a whole multiple of another tone with
which it is associated. Virtually all physical sound producers (including,
unfortunately, loudspeakers) produce complex sounds which consist of a
fundamental tone and many harmonics. Harmonics are also known (more in
musical, than home entertainment, contexts) as overtones.
Harmonic distortion When a signal (usually audio) is not reproduced perfectly, it
is said to be distorted. Harmonic distortion is a specific, and common, type of
distortion in which a given frequency that is supposed to be in the signal has
added to it overtones, or additional unwanted signals which are whole multiples of
its original frequency (harmonics). Equipment suppliers often quote a
measurement called THD or Total Harmonic Distortion. The lower the figure the
better in general. But relatively high levels of evenly numbered harmonics are
easier to tolerate – indeed, can often be attractive, making the sound 'warmer' –
than quite low levels of odd order harmonics.