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The result is determined by the lowest curve which is not touched by the measured spectrum at any position in the audio frequency range. Noise curves serve as uniform measuring standards and are referred to by many noise regulations covering a variety of locations from concert halls, rock concerts, lecture rooms and offices to clay target ...
However, decibels are a logarithimic scale, so that successive 10 dB increments represent greater increases in loudness. For humans, normal hearing is between −10 dB(HL) and 15 dB(HL), [ 2 ] [ 3 ] although 0 dB from 250 Hz to 8 kHz is deemed to be 'average' normal hearing.
A sound with a loudness of 1 sone is judged equally loud as a 1 kHz tone with a sound pressure level of 40 decibels above 20 micropascals. [1] The phon is psychophysically matched to a reference frequency of 1 kHz. [2] In other words, the phon matches the sound pressure level in decibels of a similarly perceived 1 kHz pure tone. [3]
ISO equal-loudness contours with frequency in Hz. An equal-loudness contour is a measure of sound pressure level, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. [1] The unit of measurement for loudness levels is the phon and is arrived at by reference to equal-loudness ...
Most audio components are designed to be linear across their entire operating range. Well-designed solid-state amplifiers and CD players may have a frequency response that varies by only 0.2 dB between 20 Hz to 20 kHz. [5] Loudspeakers tend to have considerably less flat frequency responses than this. Total harmonic distortion (THD)
One way to test a loudspeaker requires an anechoic chamber, with an acoustically transparent floor-grid. The measuring microphone is normally mounted on an unobtrusive boom (to avoid reflections) and positioned 1 metre in front of the drive units on the axis with the high-frequency driver. While this can produce repeatable results, such a 'free ...
Current work on this standard occurs primarily in the maintenance of IEC 60268, the international standard for sound systems. The CCIR curve differs greatly from A-weighting in the 5 to 8 kHz region where it peaks to +12.2 dB at 6.3 kHz, the region in which we appear to be extremely sensitive to noise.
Dynamic range is a measure of how small you can measure a signal relative to the maximum input signal the device can measure. Expressed in decibels, the dynamic range is 20 log (Vmax/Vmin). For example, a device with an input range of ±10 V and a dynamic range of 110 dB will be able to measure a signal as small as 10 μV.