Standard Interpretations - Table of Contents|
| Standard Number:||1910.95(a)|
In any operating state, during reasonable operation of the unit, the maximum acoustic pressure emanating from a receiver earpiece of a telephone or similar device shall not exceed 125 dBA (relative to 20 micro-Pascals) for supra-aural (on-ear) handsets, 121 dBA for insert type (in-ear) earphones, or 118 dBA for supra-aural headphones.The UL limits for maximum acoustic pressure are higher than OSHA's exposure limit for continuous noise. OSHA prohibits any exposure to continuous noise exceeding 115 dBA sound level.
The peak acoustic pressure emanating from the receiver earpiece shall not exceed 140 dB (relative to 20 micro- Pascal) with the unit in any operating state, or with a voltage surge of 800 V peak open circuit, (either polarity), having a 10 microsecond rise time to crest and a minimum decay time to half crest of 560 microseconds, and a minimum current of 10 A peak (short circuit), and applied between the tip and ring terminals of the unit.The OSHA limit for impulsive or impact noise is also 140 dB peak sound pressure level. This limit is independent of the duration of the noise impulse. There is no OSHA limit for number of exposures to impulsive or impact noise. Impulsive or impact noise must be integrated into the measurement of continuous noise exposure, however.
"Peak hold" is defined as an acoustic response having a duration less than 50 microseconds.You commented that this is an unclear and probably incorrect definition for impulse. We do not believe it is a definition for impulse, but instead, it appears to be a response time requirement for the instrument used to measure impulsive or impact noise. For example, the specification for the General Radio type 1556-B impact-noise analyzer states:
Peak Reading: Rise time is less than 50 microseconds for a value within 1 dB of peak value (for rectangular impulses).You asked what should be done about those situations where the UL requirements are not sufficiently stringent to assure that OSHA employee protection requirements are not violated. It would be helpful if those situations were eliminated by making the UL requirements more stringent, but OSHA has no legal authority to intervene. Nevertheless, employers have a legal responsibility to comply with OSHA standards and may not rely on industry or consensus standards when such standards are less protective than those promulgated by OSHA.
|Standard Interpretations - Table of Contents|