Question

The loudness of the sound is measured in the unit known as:

• A. Millimeter
• B. Centimeter
• C. Decimal
• D. Decibel

Hint:

Remember: Normal conversation occurs at roughly $60\text{ dB}$, while sound levels exceeding $80\text{ dB}$ can cause hearing impairment and are classified as noise pollution.

Answer 1

The Correct Option is D

Step 1: Understanding Sound Intensity and Perception:
Loudness is the subjective human perception of sound pressure levels. Because human hearing responds to sound intensity logarithmically rather than linearly, standard linear units are not suitable.

Step 2: Defining the Decibel ($\text{dB}$):
The standard unit to measure the loudness and intensity level of sound is the decibel ($\text{dB}$), which is a logarithmic ratio defined as: $$L = 10 \log_{10} \left( \frac{I}{I_0} \right)$$ where $I$ is the measured sound intensity, and $I_0$ is the standard threshold reference intensity ($10^{-12} \text{ W/m}^2$, corresponding to $0 \text{ dB}$).

Step 3: Eliminating Irrelevant Options:

• Millimeter Centimeter: Linear units of length/distance.
• Decimal: A base-10 numerical system.
• Decibel: The correct acoustical unit of measurement. Thus, Option (D) is the correct answer.