Decibels (dB) are used to express large ranges of which quantity in acoustics?

Decibels (dB) are used to express large ranges of which quantity in acoustics?

• A. Power
• B. Pressure
• C. Power or intensity
• D. Temperature

Answer: (C)

Decibels express very large ranges by using a logarithmic scale to compare a quantity to a reference. In acoustics, that quantity is typically power or intensity, because sound energy can vary over many orders of magnitude. The decibel is defined as 10 times the log base 10 of the ratio of powers (or intensities), so it compresses huge differences into a manageable scale: dB = 10 log10(P/P0) or 10 log10(I/I0). Sound pressure level is commonly given in dB as well, since pressure relates to intensity (power is proportional to pressure squared), via a 20 log10(p/p0) form. But the fundamental quantity being expressed on the dB scale in acoustics is power or intensity, making that option the best fit.

Decibels express very large ranges by using a logarithmic scale to compare a quantity to a reference. In acoustics, that quantity is typically power or intensity, because sound energy can vary over many orders of magnitude. The decibel is defined as 10 times the log base 10 of the ratio of powers (or intensities), so it compresses huge differences into a manageable scale: dB = 10 log10(P/P0) or 10 log10(I/I0). Sound pressure level is commonly given in dB as well, since pressure relates to intensity (power is proportional to pressure squared), via a 20 log10(p/p0) form. But the fundamental quantity being expressed on the dB scale in acoustics is power or intensity, making that option the best fit.