A pure tone is a tone with a sinusoidal waveshape.
A sine wave The sine wave or sinusoid is a mathematical function that describes a smooth repetitive oscillation. It occurs often in pure mathematics, as well as physics, signal processing, electrical engineering and many other fields. Its most basic form as a function of time is: is characterized by its frequency — the number of cycles per second, or its wavelength In physics, the wavelength of a sinusoidal wave is the spatial period of the wave – the distance over which the wave's shape repeats. It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a characteristic of both traveling waves and — the distance the waveform travels through its medium within a period, and the amplitude Amplitude is the magnitude of change in the oscillating variable, with each oscillation, within an oscillating system. For instance, sound waves are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation. If the variable undergoes regular oscillations, and a graph of the system — the size of each cycle. A pure tone has the unique property that its waveshape and sound are changed only in amplitude and phase by linear acoustic systems.
History
A pure sine wave is an artificial sound. Hermann von Helmholtz Hermann Ludwig Ferdinand von Helmholtz was a German physician and physicist who made significant contributions to several widely varied areas of modern science. In physiology and psychology, he is known for his mathematics of the eye, theories of vision, ideas on the visual perception of space, color vision research, and on the sensation of tone, is credited as the first creator of a sine wave with the 'Helmholtz siren A siren is a loud noise maker. The original version would yield sounds under water, suggesting a link with the sirens of Greek mythology. Most modern ones are civil defense or "air raid" sirens, tornado sirens, or the sirens on emergency service vehicles such as ambulances, police cars and fire trucks. There are two general types,', a mechanical device that sends compressed air through holes in a rotating plate. This is presumably the closest thing to a sine wave that was heard before the invention of electronic oscillators An electronic oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave.
Acoustic properties
Sinewaves are generally uncomfortable to the ear, and are more damaging to the ear than other noises at equal volumes. Sinewaves are often more difficult than other sounds at placing the location of its source- they seem to ‘fill the room’.
Fourier theorem
The Fourier theorem In mathematics, a Fourier series decomposes a periodic function or periodic signal into a sum of simple oscillating functions, namely sines and cosines . The study of Fourier series is a branch of Fourier analysis. Fourier series were introduced by Joseph Fourier (1768–1830) for the purpose of solving the heat equation in a metal plate states that any periodic waveform can be approximated as closely as desired as the sum of a series of sine waves with frequencies in a harmonic series Its name derives from the concept of overtones, or harmonics, in music: the wavelengths of the overtones of a vibrating string are 1/2, 1/3, 1/4, etc., of the string's fundamental wavelength. Every term of the series after the first is the harmonic mean of the neighboring terms; the term harmonic mean likewise derives from music and at specific phase The phase of an oscillation or wave is the fraction of a complete cycle corresponding to an offset in the displacement from a specified reference point at time t = 0. Phase is a frequency domain or Fourier transform domain concept, and as such, can be readily understood in terms of simple harmonic motion. The same concept applies to wave motion, relationships to each other.
The lowest of these frequencies (the fundamental frequency The fundamental tone, often referred to simply as the fundamental and abbreviated f0 or F0, is the lowest frequency in a harmonic series), which is also the inverse of the period of the waveform, determines the pitch Pitch represents the perceived fundamental frequency of a sound. It is one of the four major auditory attributes of sounds along with loudness, timbre and sound source location. When the actual fundamental frequency can be precisely determined through physical measurement, it may differ from the perceived pitch because of overtones, also known as of the tone, which is perceived by the human hearing. In music, notes The term "note" can be used in both generic and specific senses: one might say either "the piece Happy Birthday to You begins with two notes having the same pitch," or "the piece begins with two repetitions of the same note." In the former case, one uses "note" to refer to a specific musical event; in the are assigned to tones with different fundamental frequencies, in order to describe the pitch of played tones.
Categories: Pitch (music) Categories: Aspects of music | Sound | Auditory perception | Sound | Noise pollution Categories: Noise | Pollution | Pollution control technologies
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