ABR Graphical Masking Calculator - Instructions

1. Select patient age (required before plotting)
2. Plot thresholds - Click on audiograms to plot AC and BC thresholds
3. Check LEDs - Red = masking needed, Green = not needed
4. Click any LED to see masking noise level and details

Sessions allow you to save, share, and lock your audiogram data:

File Operations

Prepare Peer Review

This exports your plotted thresholds into a standardised Excel template used for ABR peer review documentation. The template is pre-filled with your threshold data, session URL, and test settings, reducing copy errors and replication work.

Results Table

Generates a formatted table of all plotted thresholds that can be copied directly into patient management systems or clinical documents. The table is formatted for easy pasting into Word or other applications.

Clicking on individual threshold values in the table copies them to clipboard with the nHL to eHL correction factor displayed. Some departments use this for annotating ABR trace PDFs with the corrected eHL values.

1 Select Patient Age

Patient age is required before plotting. Select from the dropdown or use the calculator:

• Click "Calculate from DOB + Gestational Age" to compute corrected age automatically
• Enter Date of Birth, Gestational Age at Birth, and Test Date
• DOB is not stored for privacy - only the age category is saved

2 Select Symbol Type

Threshold Modifiers

3 Click on the Audiogram

• The RED audiogram is for the Right ear
• The BLUE audiogram is for the Left ear
• Click position determines both frequency (x-axis) and dB level (y-axis)
• Frequencies from left to right: Click, 500Hz, 1kHz, 2kHz, 4kHz
• The Click column is narrower and separated by a coloured divider line

MAT = Masking Assumption Threshold - the threshold assumed for masking calculations when the actual threshold is unknown.

MAT points appear as grey symbols with ^MAT and are created automatically when you plot with ≤ or ˃ modifiers.

When you record a response (≤ modifier)

If you get a CR at 30 dBeHL or better, the calculator assumes hearing is normal and sets the MAT at 0 dBeHL. For air conduction, it will also create a bone conduction MAT at 0 dBeHL if you haven't already plotted one, since normal AC implies normal BC.

If the CR is above 30 dBeHL, the MAT is set at the level you tested at, since there may be some hearing loss present.

When there's RA (˃ modifier)

When you get RA at a level, the MAT is generally set 5 dB worse than where you tested, representing the assumption that threshold is just beyond the tested level.

For bone conduction with RA, the calculator also considers the air conduction threshold to avoid creating an impossible negative air-bone gap. If you're testing near the maximum bone conduction output (45 dBeHL or above), it assumes there's no air-bone gap and sets the BC MAT equal to the AC level.

When you have both ˃ and ≤ at the same frequency and ear

Sometimes you'll have both an RA level and a CR level for the same frequency and ear. In this case, the calculator positions the MAT to maximize the assumed air-bone gap, per clinical guidance. For AC it assumes threshold is 5 dB better than the CR level; for BC it assumes threshold is 5 dB worse than the RA level. This produces appropriate masking calculations.

Coloured LED indicators appear next to each plotted threshold showing masking status at a glance:

When you click an LED or query a stimulus level, the calculation results appear below the audiograms showing:

• Masking Required: YES or NO
• Noise Level: The dB dial setting for masking noise
• Offset: Noise level relative to stimulus level
• Cross-Hearing Risk: Risk of non-test ear responding
• Cross-Masking Risk: Risk of over-masking the test ear
• Sensitivity Analysis: How results change if ABG values differ

Query mode lets you check masking requirements at stimulus levels you haven't plotted. This is useful for:

• Planning what masking you'll need before starting a test
• Exploring "what if" scenarios at different stimulus levels
• Checking masking at a level you're about to test

Click the QUERY^? button, select AC or BC, then click on the audiogram at any stimulus level. A dashed symbol with ? appears showing the point being queried.

Fix as Threshold

After querying, if you've confirmed this as the threshold, click "Fix X dBnHL as new threshold?". The point becomes a normal plotted threshold with LED indicator, allowing you to update your audiogram as you test.

The Masking Analysis table appears below the audiograms once you have plotted points to assist with Peer Review. It shows:

• All plotted points organised by frequency and ear
• Masking status for each point (Needed/Not Needed)
• Noise level and offset when masking is needed
• Cross-masking risk indicators

Use the checkboxes below the Clear Audiogram button to customise the display for a cleaner audiogram view:

Configure these to match your equipment (in the sidebar under the mode buttons):

After selecting patient age, you can load example audiogram configurations:

• Unilateral Loss - 80dB loss in one ear, normal in the other
• Bilateral Glue Ear - 30dB air-bone gap bilaterally
• Severe Bilateral Loss - 85dB loss both ears

Profiles are available at 4kHz and 1kHz. They're useful for learning or quick demonstrations.

For users who prefer to enter values directly, use the ABG Calculator (🔢 button in header).

When you click this button from the graphical calculator after a query, your current settings are transferred automatically and masking is calculated immediately.

For validation and troubleshooting, you can verify calculations against the original Excel spreadsheet: