Which statement correctly expresses decibel level Beta in terms of the intensity ratio?

Which statement correctly expresses decibel level Beta in terms of the intensity ratio?

• A. -10 dB
• B. 0 dB
• C. 10 dB
• D. 20 dB

Answer: (B)

Decibel level for intensity uses β = 10 log10(I/I0). This makes the scale logarithmic, so multiplicative changes in intensity become additive changes in decibels. If the intensity equals the reference intensity, the ratio I/I0 is 1 and log10(1) = 0, giving β = 0 dB. So zero decibels occur when the intensity matches the reference. In general, β is positive when I is greater than I0 and negative when I is less than I0. Doubling the intensity gives about +3 dB.

Decibel level for intensity uses β = 10 log10(I/I0). This makes the scale logarithmic, so multiplicative changes in intensity become additive changes in decibels. If the intensity equals the reference intensity, the ratio I/I0 is 1 and log10(1) = 0, giving β = 0 dB. So zero decibels occur when the intensity matches the reference. In general, β is positive when I is greater than I0 and negative when I is less than I0. Doubling the intensity gives about +3 dB.