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Mains hum, electric hum, cycle hum, or power line hum is a sound associated with alternating current which is twice the frequency of the mains electricity. The fundamental frequency of this sound is usually double that of fundamental 50/60Hz, i.e.100/120Hz, depending on the local power-line frequency. The sound often has heavy harmonic content above 50/60Hz. Because of the presence of mains current in mains-powered audio equipment as well as ubiquitous AC electromagnetic fields from nearby appliances and wiring, 50/60Hz electrical noise can get into audio systems, and is heard as mains hum from their speakers. Mains hum may also be heard coming from powerful electric power grid equipment such as utility transformers, caused by mechanical vibrations induced by magnetostriction in magnetic core. Onboard aircraft (or spacecraft) the frequency heard is often higher pitched, due to the use of 400 Hz AC power in these settings because 400 Hz transformers are much smaller and lighter.
Mainshum, electric hum, cycle hum, or power line hum is a sound associated with alternating current which is twice the frequency of the mains electricity...
Kazoo The Hum – an apparently widespread phenomenon involving a low-frequency hum of unknown origin, inaudible to most people Mainshum – an electric...
periodic motion Mainshum, an electric or electromagnetic phenomenon The Hum, an acoustic phenomenon Venous hum, a physiological sensation Hum (band), a band...
of video broadcasts in the Americas and parts of Asia Interlaced video Mainshum This disambiguation page lists articles associated with the title 60 Hz...
background mainshum in the recording with long-term high-precision historical records of mains frequency changes from a database. In effect the mainshum signal...
The utility frequency, (power) line frequency (American English) or mains frequency (British English) is the nominal frequency of the oscillations of...
actually the sound source, while the lower coil is responsible for the mainshum attenuation. Alnico V magnetic bars span from one coil to the other, crossing...
energy of which produces an audible noise known as mainshum or "transformer hum". This transformer hum is especially objectionable in transformers supplied...
of electromagnetic forces. Some examples of this noise include the mainshum, hum of transformers, the whine of some rotating electric machines, or the...
electromagnetic interference caused by alternating magnetic fields from mains wiring (mainshum) and electrical appliances like transformers, motors, and computer...
low-impedance source configuration will be more resistant to noise (particularly mainshum). Signal reflections caused by an impedance mismatch at the end of a transmission...
desirable features are: high specific power per mass and volume, low mainshum, and minimal electromagnetic interference. One such application is the...
power-law colored noise in one or any number of dimensions. Mainshum (also known as the AC power hum) Whittle likelihood "ATIS Telecom Glossary". atis.org...
may be specified as graphs versus frequency, while output ripple noise (mains "hum" or switch-mode "hash" noise) may be given as peak-to-peak or RMS voltages...
causing radio frequency noise. The search for an acceptable solution to mainshum gained new impetus around 1995 as guitar players became increasingly intolerant...
common-mode rejection ratios and so will often introduce cable-borne mainshum and other common-mode interference, such as switch 'clicks', into sensitive...
up ambient, usually unwanted electromagnetic interference or EMI. This mainshum results in a tone of 50 or 60 cycles per second depending on the powerline...
1983. It featured an improved shield over the reed and pickups to reduce mainshum, which had been a problem with the 200. The last version to be introduced...
adaptable to being recorded, as it has a balanced signal which eliminates mainshum and other noise. The 122RV was the same model, but with an additional...
up to 100 kHz may sometimes be classified as audio. Sources include: Mainshum from: power supply units, nearby power supply wiring, transmission lines...
resistor–capacitor filtering to greatly reduce this crosstalk, along with 50–60 Hz mainshum. However, the sound of tonewheel crosstalk is now considered part of the...
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