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Confusion between Attenuation and Intesity change

  1. Jan 18, 2013 #1
    Dear All,
    I am basically from Bio background and doing research in Insect Physiology as Phd.
    Currently I am given a task to generate artificial insect songs using a software.
    I did it with 3 v Noise stimuli(1.5 peak to peak) and fed it to amplifier and I heard it on Amplifier.

    So now the confusion starts..
    I am also given one attenuator which attenuates with the range from -90 db to 0dB.
    Now I am suppose to play my song at 70 dB SPL. Does this mean that I have to attenuate my signal at 70dB.?

    I mean playing song at 70 dB SPL and attenuating song by 70dB..Are both same things?
    PLease help me..
    Thank you in Advance
  2. jcsd
  3. Jan 18, 2013 #2


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    Science Advisor
    Homework Helper

    The sound level in the air will depend on the transducer (loudspeaker, etc) you use to play the sound, and the distance between the transducer and the measurement position.

    You need to measure the SPL, and use the attenuator to adjust it to 70dB.
  4. Jan 18, 2013 #3


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    Science Advisor
    Gold Member

    Adding to AlephZero's measuring of the SPL,

    http://www.animations.physics.unsw.edu.au/waves-sound/quantifying/ has some good information that may help.

    e.g., these topics are from the What is a decibel? link.

    Definition and examples
    Sound files to show the size of a decibel
    Standard reference levels ("absolute" sound level)
    Logarithmic response, psychophysical measures, sones and phons
    The filters used for dB(A) and dB(C)
    Recording level and decibels (dBV and dBm)
    Intensity, radiation and dB
    Pressure, intensity and specific impedance
    dBi and anisotropic radiation
    Example problems using dB for amplifier gain, speaker power, hearing sensitivity etc.
    Occupational health and safety and the law
    Related pages
    What is a logarithm? A brief introduction.
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