Level Meter

The data-logging* Level Meter features numeric and bar graph displays. It supports sound level measurement as well as non-acoustic signal level measurements. When analyzing non-acoustic signals, the Level Meter tool measures equivalent, time-weighted rms (root-mean-square), or percentile-exceeded levels.

Measurements include equivalent level, Leq, exponential time-weighted average level, Lp, and percentile-exceeded sound level, Lx. Lp measurements can be made with slow, fast, or impulse time weighting.

Z, A, and C frequency weighting is supported for Leq or Lp measurements. When performing Lx measurements, Fast time weighting and A frequency weighting are automatically selected. (It is possible to perform Lx measurements with other time and frequency weightings by performing either an Lp or Leq measurement and then switching to Lx after the meter is stopped.)

The Level Meter includes a clip indicator, which tells the user when input clipping may have occurred during the current measurement, or when the input signal is presently being clipped.

The Level Meter can capture and share measured sound levels and supporting information, such as date and time, as well as the current GPS coordinates.

The Level Meter can save sound levels as image files, or as overlays on new or existing photos in your photo library. The Level Meter can even use the built-in camera to capture an image associated with the current measurement, and the sound level can then be overlaid on top of the photo, along with any other information you type in.

When data logging is enabled, a data log graph will be available in the Meter tool screen. You can switch between the main SLM display and the data log graph using the segmented control in the Meter's toolbar. Data can be logged as often as every 0.1 seconds for up to 8 hours, every second for up to 72 hours, or every 10 seconds for up to two weeks.

Logged data can include Lp, Lp_max, peak, Leq, L10, L50, L90, and Lx (where 'x' specifies a custom percentile).

The custom percentile value for the logged data is fixed when the measurement starts. It can still be changed for the live display while the meter is running, but the logged data will still use the value that it started with.