Measurements include equivalent level, Leq, and exponential time-weighted average level, Lp.
Z, A, and C frequency weighting is supported for both Leq and Lp measurements.
Time Weighting (Lp)
The Level Meter offers three time
weightings for the Lp sound level measurement: Fast, Slow, and Impulse.
The fast time weighting computes
the exponential-time-weighted average sound level with a time constant of 125 ms.
The slow time weighting uses a time constant of 1000 ms, or 1 second.
The impulse time weighting uses a rise time constant of 35 ms and a decay time constant of 1500 ms.
Averaging Time (Leq)
The Level Meter offers three averaging times
for the Leq sound level measurement: 1/8s, 1s, and ∞.
With 1/8s or 1s, the Leq is calculated over a 1/8 or 1-second time interval, respectively.
With ∞, the Leq is calculated over the entire duration of the measurement. This is the traditional
behavior in prior versions of the Level Meter.
Auto Stop Options
Level Meter measurements can be configured to automatically stop after a predetermined amount of
The elapsed time after which the current measurement will stop, or for which sound level data
will be logged, can be set in 1 second increments up to two weeks in duration.
SoundMeter can log current sound levels for a set amount of time. If
Auto Stop is disabled, data logging will continue after the specified duration has been reached and
only the most recent data (as much as indicated by the duration) will be kept. When Log Levels 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 by tapping the page control or by swiping left or right with a single finger.
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. Larger intervals can also be specified.
Reset Leq/max/peak at Intervals
This option allows the Leq, Lp_max, and peak levels to be reset each time they are logged. With this option, it is possible
to log a short Leq of 0.1 seconds for up to 8 hours.
Auto Save Log
SoundMeter includes the option to automatically save logged sound levels to a data file after the specified duration
has been reached. If Auto Stop is disabled, SoundMeter will continue to save the current logged data to a new data file
each time the duration is reached. This means that sound levels can be logged at the desired interval for an arbitrarily
long period of time.
Log File Format
When logged sound levels are automatically saved, it will be to a file of the specified format.
Base File Name
When logged sound levels are automatically saved, the filename will begin with the specified base file name and end with a
time stamp that includes both date and time. The format of the filename's time stamp will be yyyyMMddHHmmss,
where y, M, d, H, m, and s refer to year, month, day, hour, minute, and second, respectively.
Maximum Auto Saves
The number of times SoundMeter will automatically save logged data, in a single measurement session, is limited to the
value specified here.
Several events are defined which can trigger a local notification. This offers a way to be alerted when an event, such as a sound level exceeding a user-defined threshold, occurs.
Date and Time
When saving or exporting Level Meter measurements, you can have the date and time
automatically inserted. If you want to have the date and time included automatically, set this
switch to "On".
When saving or exporting Level Meter measurements, you can have the current GPS
coordinates automatically inserted. If you want to have the current location included
automatically, set this switch to "On".
*In SoundMeter X, most tools are available only via subscription (subscriptions can be purchased within SoundMeter X).
*SoundMeter Basic only includes tools and features found in the Standard subscription.