Decibels Flashcards
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Questions and Answers

What is the unit of sound intensity named for?

Alexander Graham Bell

What is a decibel a relationship between?

Two values of power

In diagnostic ultrasound, decibels are used for what?

Attenuation, gain and dynamic range

What happens to sound as it travels in the body?

<p>Weakens</p> Signup and view all the answers

What happens to a sound wave after it is received by the transducer?

<p>Amplified</p> Signup and view all the answers

What is the standard measurement tool for sound intensity?

<p>Decibel notation</p> Signup and view all the answers

Decibels are based on what mathematical construct?

<p>Logarithms</p> Signup and view all the answers

What do decibels measure?

<p>Strength</p> Signup and view all the answers

How many intensities are needed in order to use decibels?

<p>2</p> Signup and view all the answers

What are the two intensities used in decibel measurement?

<p>Reference or starting level and the actual level</p> Signup and view all the answers

What does decibel (dB) measure?

<p>Relative distance between 2 sound intensities</p> Signup and view all the answers

The logarithmic relationship of decibels allows large ranges of sound intensity to be handled in more manageable units.

<p>True</p> Signup and view all the answers

What does the log of a number represent in terms of powers of 10?

<p>The number of 10s that are multiplied to create the original number</p> Signup and view all the answers

To obtain the number 100, what multiplication is done using 10?

<p>10 x 10</p> Signup and view all the answers

In logarithms, when they say 'increase', what does it refer to?

<p>How many 0's after 1</p> Signup and view all the answers

What does the Richter scale measure?

<p>Earthquakes</p> Signup and view all the answers

What is the log of 1000?

<p>3</p> Signup and view all the answers

For powers of 10, what can you do?

<p>Just count the zeros</p> Signup and view all the answers

What is decibel notation?

<p>Logarithmic</p> Signup and view all the answers

Decibel notation measures absolute numbers.

<p>False</p> Signup and view all the answers

What do positive decibels report?

<p>Signals that are increasing in strength or getting larger</p> Signup and view all the answers

When a wave intensity doubles, what is the relative change in decibels?

<p>+3</p> Signup and view all the answers

If the decibel is positive, what does it indicate about the unit?

<p>Increasing</p> Signup and view all the answers

What portion does -10 dB represent in terms of original power?

<p>1/10</p> Signup and view all the answers

If intensity or amplitude has a factor of 4, how many decibels is that?

<p>6 dB</p> Signup and view all the answers

A bee's buzz is often rated with a decibel rating of 40 dB. Normal conversation is rated at 60 dB. How many times more intense is normal conversation compared to a bee's buzz?

<p>100</p> Signup and view all the answers

Study Notes

Units of Sound Intensity

  • Bel: A unit named after Alexander Graham Bell, used to measure sound intensity.
  • Decibel (dB): Represents a relationship between two power values, typically used in sound measurements.

Application in Diagnostic Ultrasound

  • Decibels measure attenuation, gain, and dynamic range in ultrasound.
  • Sound weakens as it travels through the body, requiring amplification after being received by the transducer.

Decibel Notation

  • Standard Measurement: Decibel notation is a logarithmic scale.
  • Based on logarithms, where log of a number signifies how many times 10 is multiplied to achieve that number.
  • Decibels do not measure absolute sound levels but relative changes.

Positive and Negative Decibels

  • Positive decibels indicate increasing signal strength, with specific correlations for intensity changes (e.g., +3 dB means double the intensity).
  • Negative decibels reflect a decrease in intensity, with -3 dB signifying a reduction to half the original value.

Decibel Values and Relationships

  • Each doubling of sound intensity corresponds to an increase of 3 dB.
  • A 10-fold increase results in a 10 dB increase.
  • Calculating relative changes: A factor of 4 results in an increase of 6 dB, while a reduction to one-tenth is expressed as -10 dB.

Examples of Sound Intensity Changes

  • A sound intensity increase by a factor of 16 corresponds to a 12 dB increase (4 doublings).
  • The comparative intensity of sounds can be assessed: normal conversation at 60 dB is 100 times more intense than a bee's buzz at 40 dB.

Practical Applications and Measurements

  • Decibels facilitate managing large ranges of sound intensity. For powers of 10, counting zeros determines the logarithmic increase.
  • Sound intensity is proportional to the square of the amplitude; quadrupling amplitude increases intensity by a factor of 16.

Miscellaneous

  • Richter Scale: Another application of logarithmic measurement, used to quantify earthquake magnitudes.

These notes provide a concise overview of the principles and applications of decibels in sound intensity measurement and related concepts.

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Explore key terms and definitions related to decibels through these flashcards. Learn about the unit of sound intensity, its applications in diagnostic ultrasound, and how sound weakens as it travels through different media. Perfect for students seeking to understand sound measurement concepts.

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