atom03:Sound glossary
Absorption A way to manipulate sound. The tendency of sound waves to be soaked up by soft surfaces.
Amplifier A way to manipulate sound. Increases the amplitude of a signal.
Attenuate A way to manipulate sound. To make the perception of sound weaker.
Conductor element that allows the free transmission of sound.
dB (Decibel) A relative unit of measure between two sound or audio signal levels. A difference 1 dB is considered to be the smallest that can be detected by the human ear.
Dispersion The area throughout which the sound produced is distributed.
Distortion A way to manipulate sound. The alteration of the original shape (or other characteristic) of a sound waveform.
Dynamic Range The difference between the softest and loudest extremes within an audio signal.
Efficiency The ratio of a device's energy output to its energy intake.
Filter A way to manipulate sound. A device that removes unwanted frequencies or noise from a signal.
Inductance A circuit's opposition to a change in current flow. Sound waves are often described in terms of sinusoidal (smooth repetitive oscillation) two-dimensional waves, and are characterized by the following properties:
Amplitude the magnitude of change in the oscillating variable - It translated into the strength of sound waves and determines loudness.
Frequency the number of occurrences of a repeating event per unit time. The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency. For example, if a newborn baby's heart beats at a frequency of 120 times a minute, its period (the interval between beats) is half a second.
Wavelength 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.
Sound pressure level The sound pressure level is used to describe the amplitude of the sound wave. However the sound intensity is also a way to describe the amplitude of a sound wave. The difference between the two is the following; the sound intensity level (SIL) is the power density from a sound source at the measurement point and the sound pressure level (SPL) is the sum of the sound pressure waves at the measurement point. The SIL and the SPL are equivalent if there is only one pressure wave from the sound source. When extra pressure waves due to reflection occur the SIL and SPL differ. It's confusing that both the SIL and SPL are able to describe sound amplitudes, however a general reference to sound level implies that the SPL is being use. The pressure component corresponds most closely to what we hear.
Sound intensity level The sound intensity represents the watt (energy) per unit area from a sound source. This formula describes the sound intensity level: 10log10(Iactual/Iref)
Speed of sound (Velocity) distance travelled during a unit of time by a sound wave propagating through an elastic medium. The speed of the sound wave in solids is affected by the density and the Young's modulus of the material. The higher the elastic modulus of the material the higher the speed of propagation and the higher the density value (the higher the effective mass) and the speed of propagation decreases. Sound usually propagates through air. The speed of sound in a gas is strongly affected by the absolute temperature and the molecular weight of the gas. The less the mass of the gas the faster the speed of sound and also the higher the temperature the faster the speed of sound. In dry air at 20 °C (68 °F), the speed of sound is 343.2 metres per second (1,126 ft/s). This is 1,236 kilometres per hour (768 mph), or about one kilometer in three seconds or approximately one mile in five seconds. Velocity is linking the wave length and the frequency together this linkage is described by the folllowing equation: v=f*labda (v (velocity) in ms-1, f (frequency) in Hz and labda (wavelength) in metres)
Direction Information contained in the relative position of one point with respect to another point without the distance information
Diffraction Uses the edges of a barrier as a secondary sound source that sends waves in a new direction.
Doppler effect The change in frequency of a wave for an observer moving relative to the source of the wave. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from an observer. The received frequency is higher (compared to the emitted frequency) during the approach, it is identical at the instant of passing by, and it is lower during the recession.
Omnidirectional Capable of picking-up sound or radiating sound equally from all directions
Phase The relationship of an audio signal or sound wave to a specific time reference.
Pitch The degree of highness or lowness of a tone.
Sound Level Meter A device that measures, in dB, the amplitude of sound waves.
Sound Reinforcement The use of electronic devices to reinforce, alter or increase the level of sound.
Tone Sound that can recognized by its regularity of vibration; The overall quality of sound.
Unidirectional Picking up sound primarily from one direction.
Vibration The analogous motion of particles of mass the analogous motion of the particles of a mass of air, whose state of equilibrium has been disturbed, causing the transmission of sound.
