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decibel

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Secondary Information

Definition

A decibel (dB) is a unit of measurement used to quantify the loudness of a sound. It is a logarithmic unit, which means that a difference of 10 decibels corresponds to a tenfold increase in loudness.

The decibel scale is a relative scale, which means that it is not based on any absolute standard. The reference level for the decibel scale is the threshold of hearing, which is the quietest sound that a human can hear.

The decibel scale is used to measure a wide range of sounds, from the softest whispers to the loudest explosions. Some common sounds and their decibel levels include:

  • Whisper: 20 dB
  • Normal conversation: 60 dB
  • Vacuum cleaner: 70 dB
  • Motorcycle: 90 dB
  • Rock concert: 120 dB
  • Jet engine: 140 dB

The decibel scale is also used to measure the loudness of the music. The loudness of music is typically measured in decibels SPL (Sound Pressure Level). The maximum loudness of music that is considered safe for human hearing is 100 dB SPL.

How can the word be used?

The decibel scale is used to measure the relative loudness of sounds.

decibel

Different forms of the word

Noun: A decibel is a unit of measurement for sound intensity.

Adjective: Decibel-related terms include "decibel level" and "decibel scale.".

Adverb: The word "decibels" can be used as an adverb to indicate a sound level. For example, you might say that "the concert was so loud it was painful to listen to at 110 decibels.".

Etymology

The word "decibel" is a portmanteau of the Latin word "decem", which means "ten", and the word "bel", which is a unit of measurement for sound intensity that was named after Alexander Graham Bell.

Question

How many decibels is the sound of a motorcycle?

AQA Science Exam Question and Answer

Question:

Question: Define the decibel (dB) as a unit of measurement for sound intensity. Explain the concept of logarithmic scale and why it is used to express sound levels. Finally, provide an example of a common sound and its corresponding decibel level.

Answer:

  • The decibel (dB) is a unit used to measure sound intensity, representing the relative loudness or volume of a sound. It is a logarithmic scale, which means that each increase of 10 dB corresponds to a tenfold increase in sound intensity. This scale is employed because the human perception of sound is nonlinear, and logarithms help us express a wide range of sound levels in a more manageable manner.
  • For instance, a normal conversation typically registers at around 60 dB, while a lawnmower might produce around 90 dB. The difference between these two sound levels is not a factor of 3 (90 divided by 60), as it might seem on a linear scale, but rather a factor of 1000 (10 dB increase corresponds to a 10 times increase, so 30 dB increase is 10 x 10 x 10 = 1000). Thus, the logarithmic scale allows for a more intuitive representation of sound intensity variations.