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Guilherme Mazui

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What is the Difference Between Sound Intensity and Loudness?

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The difference between sound intensity and loudness lies in their definitions and how they are perceived:

  • Sound Intensity: This is the power of the sound in Watts divided by the area the sound covers in square meters. It is a physical quantity that can be measured objectively and is independent of the sensitivity of the human ears. Sound intensity is measured in Watts per square meter.
  • Loudness: This is the measure of the response of the ear to the sound. It relates the intensity of any given sound to the intensity at the threshold of hearing and is measured in decibels (dB). Loudness is the human perception of sound intensity and is dependent on the sensitivity of the human ears.

In summary, intensity is a physical quantity that can be measured objectively, while loudness is a subjective sensation experienced by humans.

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  • What is the Difference Between Sound Intensity and Loudness?
  • Comparative Table: Sound Intensity vs Loudness

    • Comparative Table: Sound Intensity vs Loudness

    Sound intensity and loudness are two different aspects of sound that are related but not directly interchangeable. Here is a table summarizing their differences:

    Feature Sound Intensity Loudness
    Unit of Measurement Watts per square meter (W/m^2) Decibels (dB)
    Description The amount of energy transferred by sound waves per unit area per unit time. The subjective perception of sound intensity, which varies among individuals.
    Logarithmic Scale No Yes
    Decibel Increase An increase in sound intensity by a factor of 10 corresponds to an increase of approximately 3 dB. An increase of 10 dB represents a 10-fold increase in sound intensity and a doubling of perceived loudness.
    Examples Sound intensity levels in watts per meter squared for some familiar sounds:
    - Faintest sound heard by human ear: 1.00 x 10^-12 W/m^2
    - Normal conversation: 1.00 W/m^2
    - Lawnmower: 1.00 W/m^2    		 Loudness measured on a logarithmic scale:
    - Faintest sound heard by human ear: 0 dB
    - Normal conversation: 60 dB
    - Lawnmower: 90 dB

    To relate the two concepts, a 90 dB sound is 30 dB greater than a 60 dB sound, which means it is 1,000 times more intense (assuming linearity). However, the perceived loudness of a sound increases at a faster rate than its intensity. For example, a sound that is 10 times more intense than another sound corresponds to an approximately 3 dB increase in sound intensity level but seems twice as loud.

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    Guilherme Mazui

    Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.