EZLD Level-Dependent Hearing Protector Test Application

Configuration is quick and easy. Simply select audio hardware device outputs, sound system sensitivity, sample rate, and microphone channels. Browse files and select WAV files to provide the desired test signals and set loop duration of test signals. Global maximum values for peak voltage and SPL ensure that the system and test subjects are protected.

The sound field tab allows the user to calibrate the sound field based on the sound system’s sensitivity. A calibration offset for each type of test signal is saved to ensure the level is exactly as expected at the reference position before testing begins. The most recent date and time of calibration for the loaded configuration is displayed and can be updated and saved with the config file. The RMS and peak voltages resulting from the signal level selected are displayed for either linear or A-weighting.

Depending on the type of hearing protector selected for testing, the relevant workflow parameters are shown and edited on this tab. Select criteria level, desired overshoot, timing and range of levels, and EZLD will do all of the busy work for you and automatically export data to the directory and default files chosen here.

The diffuse field equivalent level calibration tab quickly calculates and stores the transfer function for the test subject’s (or a fixture’s) ear relative to a reference microphone. This accounts for the frequency dependent difference between the actual level in the room and what the ear experiences. The option to enter the transfer function manually or copy and paste from Excel is also given.

EZLD will generate an Excel file containing data sheets for each signal type at each level, plus all of the calibration information. The user also has the option of customizing their own template file.

The results of each signal tested are plotted as a transfer function of the hearing protector with the criteria level shown as well. Each plot can be hidden by clicking the corresponding box in the key. The graph can be scaled by entering new minimum or maximum values on either axis.

The auto occluded tab is where the actual test is performed. Based on the setting chosen during configuration, the entire test sequence will run automatically when the operator presses “Start”, or can be started from the highlighted signal and level. The data collected for each run is displayed, and pass/fail indicators will alert the operator if the criteria of the test is not met.

The set levels tab ensures that the previous calibration settings will work given the measured (or imported) DFE correction. If there is a discrepancy, EZLD recalculates the relevant parameters, suggests them to the user, and they can be updated by simply clicking “Accept”.