A harmonic series is the sequence of sounds—pure tones, represented by sinusoidal waves—in which the frequency of each sound is an integer multiple of the fundamental, the lowest frequency.Pitched musical instruments are often based on an acoustic resonator such as a string or a column of air, which oscillates at numerous modes simultaneously. At the frequencies of each vibrating mode, waves travel in both directions along the string or air column, reinforcing and canceling each other to form standing waves. Interaction with the surrounding air causes audible sound waves, which travel away from...

An equal temperament is a musical temperament, or a system of tuning, in which the frequency interval between every pair of adjacent notes has the same ratio. In other words, the ratios of the frequencies of any adjacent pair of notes is the same, and, as pitch is perceived roughly as the logarithm of frequency, equal perceived "distance" from every note to its nearest neighbor. In equal temperament tunings, the generating interval is often found by dividing some larger desired interval, often the octave (ratio 2:1), into a number of smaller equal steps (equal frequency ratios between successive...

Шапокля́к (фр. chapeau claque, от chapeau [шапо] — шляпа и claque [кляк] — шлепок, удар ладонью) — мужской головной убор, разновидность цилиндра, отличающийся тем, что его можно было складывать. Идея складного цилиндра, по некоторым предположениям, возникла по аналогии со складными треуголками конца XVIII века, которые было принято в сложенном виде держать под мышкой. Изобретателем шапокляка считается французский шляпник Антуан Жибюс (фр. Antoine Gibus). Первые образцы складного цилиндра начали продаваться в Париже и Лондоне в середине 1820-х гг. и, как указывает Р. М. Кирсанова, уже к 1829 г....

Shapoklyak (Russian: старуха Шапокляк, Staruha Shapoklyak - Old Lady Shapoklyak) was a popular villain from a story about Cheburashka written by Russian writer Eduard Uspensky. The first appearance of Shapoklyak (in the movie) was in the animated film Gena the Crocodile (1969) by Roman Kachanov (Soyuzmultfilm studio). She appears as an old woman, wearing an outdated hat and carrying a purse, in which she carries her pet rat Lariska. In the film Cheburashka Goes to School (1983) she admits that she has not received secondary education and is sent to school together with Cheburashka. Her name is...