The Max Levels tool presents a pair of traffic-light-style indicators to visually identify whether noise levels have exceeded certain user-defined limits. Though designed for sound level measurement, Max Levels also supports non-acoustic signal levels (given in decibels). When analyzing non-acoustic signals, the Max Levels tool measures time-weighted or unweighted rms (root-mean-square) levels.
Each indicator (designated A and B for the left and right indicators, respectively) can be assigned to monitor the overall level of the selected input channel, or levels of individual octave frequency bands. Each indicator is labeled with a user-definable title. Overall and octave-band limits can be adjusted independently for the A and B indicators.
Low and high limits are specified for the yellow and red indicator 'lights,' respectively. For octave band limits, if the level in any octave band exceeds a low or high limit, the corresponding 'light' in the indicator will be lit.
By default, the lights in each indicator represent the maximum level since the current measurement began. So once a yellow or red light is lit, a lower light cannot be lit until the measurement is restarted. Indicator behavior can optionally be set to display both current and maximum levels. In this case, the centers of the lights indicate the current level and the outer rings represent the maximum level.
When the iOS device is in landscape orientation, Max Levels will also show either the overall level of the selected input channel, or a graph of the individual octave frequency band levels. The overall level display will show the current, max, and peak levels. The octave graph will display the current levels in bars and the max level as a stepped line above the bars.
Measurements include exponential time-weighted average level, Lp, and equivalent level, Leq. Lp measurements can be made with slow, fast, or impulse time weighting. Leq measurements can be calculated over time intervals of 1/8 or 1 second, or they can be calculated over the duration of the entire measurement.
Z, A, and C frequency weighting is supported for both Leq and Lp measurements.
Max Levels includes a clip indicator in the red circle of each indicator, which tells the user when input clipping may have occurred during the current measurement, or when the input signal is presently being clipped.
Max Levels can capture and share measured sound levels and supporting information, such as date and time, as well as the current GPS coordinates.
Max Levels can save its display to high resolution PDF image files.