How to perform the acceptable noise level (ANL) test with Equinox Evo

11 March 2025

10 mins

Reading

Test procedure

Launch the Equinox Suite from Noah, OtoAccess® or standalone.

Click on the AUD tab on the upper right-hand side of the screen. Perform audiometry before the ANL test as this determines the start level for the test.

Click on Menu, Tests and then select ANL.

Test conditions

Once in the ANL test screen, you will see that there are four different conditions which you can choose to measure (Table 1).

Condition	Measurement
MCL High	Loudest comfortable level without competing noise
MCL Low	Lowest comfortable level without competing noise
MCL Real	Most comfortable level without competing noise
BNL	MCL Real with competing noise manipulated to find an ANL value

Table 1: The four conditions of the ANL test.

It is not essential to perform MCL High and MCL Low for the ANL test, but these are also good indicators of the patient’s comfortable hearing range.

MCL High

Click on the MCL High icon and click play. This will loop your speech material.

For this test, the patient is instructed to increase the loudness of the speech until it is too loud. — **Figure 2:** MCL High test screen.

Increase and decrease the stimulus intensity to match the patient’s loudest MCL.

There will be no other change in the display to represent this, only the level in the MCL High icon box.

MCL Low

Click on the MCL Low icon and click play. This will loop your speech material.

Increase and decrease the stimulus intensity to match the patient’s lowest MCL.

The display will change within the icon, but a predicted MCL Real will also be generated as a midpoint between the MCL High and MCL Low.

MCL Real

Click on the MCL Real icon and click play. This will loop your speech material.

If you have performed the MCL High and MCL Low, you should already have a predicted MCL value here. If not, then increase/decrease the intensity to find a suitable level for the patient’s MCL.

For this test, the patient is instructed to increase or decrease the loudness of speech until it is at a comfortable listening level. — **Figure 4:** MCL Real test screen.

Again, the display will not change, other than inside the icon for your test condition.

BNL

Click on the BNL icon and click play. This will loop the same speech material but also introduce the background masking noise.

For this test, the patient is instructed to turn up the background noise level until it is too loud. Then turn down the background noise level until the speech material is very clear. Finally, turn up the background noise level until the patient reaches the maximum level that they would be willing to put up with for a long time while following the speech material. In this example, the patient’s ANL value is 10 dB and the patient’s performance prediction with amplification is 39%. — **Figure 5:** BNL test screen.

Increase/decrease Channel 2 to find a level of competing noise which the patient would be comfortable to listen to alongside their target material. While doing this, you will notice the display will change to reflect the patient’s ANL value and the prediction percentage of how well they will perform with amplification.

Note: You can customize the instructions displayed in the test screen by entering the ANL setup (Figure 6).