What peak level measures
LCpeak, also written LCpico in Spanish, expresses the level corresponding to the highest instantaneous C-weighted sound pressure recorded during measurement. It is particularly important for impacts. It differs from the equivalent level, which averages energy over time, and from the maximum obtained with time weightings such as Fast or Slow.
Related concept: Workplace noise.
Which value to retain
Where several samples are taken, identify the highest valid peak and the event responsible. Peaks are not averaged as though they were exposure doses. Sampling duration and timing must capture relevant events; failure to record an impact outside the sample does not demonstrate that the impact does not occur.
Spanish reference values
Royal Decree 286/2006 establishes peak values of 135 dB(C) for the lower exposure action value, 137 dB(C) for the upper exposure action value and 140 dB(C) for the exposure limit value. Hearing protection is not deducted when comparing with action values. Assessment against the limit considers attenuation from the hearing protectors actually used, through an appropriate estimate.
Measurement quality
The instrument must have a peak function, suitable weighting and adequate range. Microphone or electronic overload can prevent the true maximum being determined. Work events must also be distinguished from accidental knocks to the microphone. This review requires evidence from the record and observation; maxima must not be removed merely because they are inconvenient.
Hypothetical example
An assessment records a peak of 138 dB(C) during an operation. Even if daily exposure remains below its upper action value, the peak exceeds its own. Measures associated with that finding must be adopted and control of the task reviewed; the two criteria neither replace nor average each other.
Interpretation and limits
Near a reference value, consider measurement limitations and make a justified preventive decision. Uncertainty calculated for the equivalent daily exposure level should not automatically be applied to the peak. The number needs context: instrument, event, position, task and existing controls. This article cannot diagnose hearing damage or establish workplace safety from one figure.
