Question

Maximum noise level from a tractor near the operator's ear should not exceed

• A. 110 dB
• B. 100 dB
• C. 95 dB
• D. 90 dB

Hint:

Permissible 8-hr continuous noise threshold = 90 dB(A). Every 5 dB increase halves the safe exposure time (95 dB $\rightarrow$ 4 hrs, 100 dB $\rightarrow$ 2 hrs).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Occupational safety and health administrations (OSHA ISO 5131) regulate permissible acoustic noise exposure levels for heavy machinery operators to prevent permanent noise-induced hearing loss (NIHL).
Key Formula or Approach:
\[ \text{Noise Dose } (D) = \sum \frac{C_i}{T_i} \le 1.0 \quad (T = 8\text{ hours for } 90\text{ dB(A)}) \]

Step 2: Detailed Explanation:
According to international tractor test codes (OECD ISO BIS 12180):
Continuous acoustic sound pressure level at the operator's ear level for an 8-hour working shift should not exceed \(90\text{ dB(A)}\).
Exposure above \(90\text{ dB}\) requires either structural cabin noise dampening or mandatory personal protective hearing equipment (ear muffs).

Step 3: Final Answer:
Hence, the maximum noise level near the operator's ear should not exceed 90 dB, matching option (D).