Sound Level Meter

Sound Level Meter with image of SM30, SM90 and SM50

Sound Pressure Level

A sound level meter does exactly what its name suggests – measures sound pressure level in decibels. This gives us a numerical reading so we can see exactly how loud something is. Measuring sound pressure level can be important in many different applications. A common use of a sound level meter would be to measure the sound coming from a factory or airport, ensuring that there is not an excessive amount of noise pollution. Another typical use of sound level meters is the monitoring of concerts or events. In addition to making sure the noise is kept under legal limits, it is also very important to make sure the sound pressure level does not cross the threshold in which lasting damage can be done to the human ear.

Sound Level Meter on Bedrock SMxx Devices

The Bedrock SM30, SM50, and SM90 all come standard with a sound level meter module already on the device. Our meters comply either with IEC 61672 Class 2 and ANSI S1.4 Type 2 (SM30 and SM50) or IEC 61672 Class 2 and ANSI S1.4 Type 1 (SM90). It is classified as a group X instrument.

The following sound level meter settings are supported:

  • Time weighting: Fast (F) and Slow (S)
  • Frequency weighting: Z (linear, unweighted), A-weighted, C-weighted
  • Max hold (holds and displays the maximum level during the measurement interval; used with either Fast or Slow time weighting)
  • Equivalent continuous (EQ): computes the time-integrated level over the measurement interval; the level shown corresponds to the level of a continuous signal containing the same amount of energy as the measured signal.
  • Peak values (PK): the highest instantaneous value within an interval

LAEQ Logging

The LAEQ logging module is intended for long-term monitoring and logging applications. When running this module, the Bedrock SMxx keeps track of how the equivalent continuous A-weighted sound pressure level (LAEQ) develops over time. This is displayed on the device and also logged, for download to a PC later on.


This module can be used for several purposes:

  • Monitoring of environmental noise sources
  • Monitoring and logging of sound levels at music venues
  • Measuring sound levels of multiple events across a large time span (e.g.
    measuring of multiple train passages)