Introduction to decibel, sound power, intensity and pressure. Sound Intensity, Power and Pressure Levels The logarithmic decibel scale is convenient when adding signal values like sound power, pressure and others from two or more sources.īackground noise frequencies that interferes with speech. The phonetic alphabet used in international aircraft communications.
Outdoor ambient sound pressure levels (dBA) in rural and urban business and industrial environments with or without limited traffic. Maximum recommended sound pressure levels in rooms like kindergartens, auditoriums, libraries, cinemas and more.Įstimate noise generated by air flow in ducts. The rules of logarithms - log 10 and log e for numbers ranging 1 to 1000. Sound pressure filters that compensates for the hearing sensed by the human ear. Noise is usually defined as unwanted sound - noise, noise generation, silencers and attenuation in HVAC systems. Room acoustics and acoustic properties, decibel A, B and C, Noise Rating (NR) curves, sound transmission, sound pressure, sound intensity and sound attenuation.Įngineering related topics like Beaufort Wind Scale, CE-marking, drawing standards and more. 10000 raises its level by 40 dB and so onĪ ref = amplitude level level (signal unit).Increasing the sound intensity by a factor of The difference in decibel between sound intensity 10 -8 W/m 2and sound intensity 10 -4 W/m 2 ( 10000 units) can be calculated as = 120 dB Example - Sound Intensity and Decibel The noise level from the fan in decibel can be calculated as = 140 dB Example - Sound Power from a FanĪ fan creates 1 W of sound power. The sound power in decibel from a source with the highest possible to hear sound power can be calculated as ġ00 W is almost the highest sound power possible to hear. Sound power from common sources - tools, fans, jets.
The sound power in decibel from a source with the lowest sound hearable can be calculated as S ref - reference signal - intensity or power level (signal unit)ġ0 -12 W is normally the lowest sound power possible to hear and this value is normally used as the reference power in sound power calculations. S - signal - intensity or power level (signal unit) S = S ref 10 (L / 10) (2) Decibel Calculator If the decibel value and reference level are known the absolute signal level can be calculated by transforming (1) to Note! - the decibel value of a signal increases with 3 dB if the signal is doubled (L = 10 log (2) = 3). The signal units depends on the nature of the signal - can be W for power.Ī decibel is one-tenth of a Bel - named after Alexander Graham Bell, the inventor of the telephone. S ref = reference signal - intensity or power level (signal unit)ĭecibel is a dimensionless value of relative ratios. S = signal - intensity or power level (signal unit) The decibel level of a signal can be expressed as