Which of the following is an accurate statement about octave band analysis?

• A. It measures energy in only a single narrow frequency band.
• B. It uses time-domain evaluation exclusively.
• C. It measures the speed of sound in air.
• D. It is performed to gather information on the energy of sound over a range of frequencies.

Answer: (D)

Octave band analysis examines how sound energy is distributed across different frequency ranges rather than at a single frequency. It filters the sound into bands that span an octave (each band covers a range whose upper and lower limits differ by about a factor of two) and measures the energy or sound level in each band. This creates a spectrum showing which parts of the frequency range carry more energy, which is essential for understanding how noise affects people and how to target control measures.

Because of that, this method is about energy across a range of frequencies, not just one narrow frequency. It’s not a time-domain-only assessment, and it doesn’t measure the speed of sound in air. The statement that it gathers information on the energy of sound over a range of frequencies is the accurate description.