Below, you can find quick answers to frequently asked questions on the Audible Contrast Threshold (ACT) test. For more detailed information, please refer to the Interacoustics Academy complete guide or the ACT quick guide.
You need to complete an audiogram before performing ACT. And you may choose to perform ACT straight after completing audiometry. However, as long as an audiogram is selected, you can perform ACT at any stage of the client journey.
You can perform ACT on anyone over the age of 18 who can complete pure tone audiometry. There may be cases where you may consider whether the test is appropriate for your client, such as in the following instances:
Before performing ACT, please consider the patient’s medical history alongside clinical judgement on whether you deem it suitable for your patient.
ACT is an above-threshold test, but the risk to someone with tinnitus is low. You should always make a judgement based on your client’s symptoms and triggers.
ACT studies have not been carried out with a pediatric population yet. The normative data is based on the adult population only and therefore, the recommendation is to perform ACT on clients over the age of 18.
ACT is a tool for predicting your client’s aided speech‑in‑noise ability. If you perform ACT, there is no need to do a speech-in-noise test unless your local protocol requires it.
ACT is a binaural test with each ear being presented with a signal based on pure tone audiometry. Cross hearing is not an issue for ACT.
You will need:
Your Affinity Suite software version must be at least 2.21.
It is a test within the AUD module that you access in the same way as other AUD-based tests.
A standard signal is presented for normally hearing adults. After conducting pure tone audiometry, the ACT stimulus is automatically adjusted to account for the hearing loss at frequencies between 250 Hz and 4 kHz for each ear. The ACT stimulus is a spectro‑temporally modulated sound imposed on top of bands of pink noise. The stimulus is non‑language specific but simulates the characteristic patterns of speech.
The ACT test is automatically adjusted based on pure tone audiometry results. This means the ACT stimulus is clearly audible for all clients. For a person with normal audiometric hearing thresholds, the ACT stimulus is presented at 63 dB SPL, aligned with conversational speech. For clients with hearing loss, audibility is considered for each ear and each 1/3-octave band in the stimulus frequency range, with the stimulus shaped such that there is at least 15 dB of audibility in all 1/3-octave bands.
Please note, for this reason, we are unable to provide frequency-specific limits for each threshold of a given severe hearing loss. A message will appear in the software to indicate if the transducers are not able to produce 15 dB above the threshold. This will not stop you from performing ACT. Depending on the shape of the audiogram, the ACT value can still give you valuable information.
The reference stimulus and ACT signal are differentiated by whether there is modulation or not.
As in pure tone audiometry, some ACT runs may indicate inconsistent responses by the client. False positives (for instance, the client pressing the button too often) are automatically registered by the software and shown in the top right-hand bar of the ACT screen.
You can address false negatives (for instance, if the client does not respond to an ACT stimulus that they previously responded to, at the contrast level being tested) by altering the testing method. In the case of inconsistent runs, it can be helpful to deviate from the Hughson-Westlake (2 down, 1 up) procedure.
The ACT diagnostic test is an above-threshold, non-language specific test that quantifies an individual’s real-world ability to hear in noise, with the intention of determining the level of help‑in‑noise needed from their hearing aid. The ACT test applies the shape and levels of a client’s audiogram to deliver an above-threshold stimulus (a siren-like sound) to objectively map their hearing-in-noise ability.
In other words, where the audiogram measures the quantity of hearing, ACT measures the quality of hearing. This makes ACT a robust assessment that reflects a person’s real-world hearing abilities.
nCL stands for normalized Contrast Level. It refers to the amount of modulation applied to the signal for the client to hear the contrast. This means, the higher the nCL value, the more contrast the client needs to hear it.
The ACT value denotes the level of contrast against the background noise a client needs to detect the ACT stimulus. A normal ACT value is between minus 4 and plus 4 dB nCL.
If the ACT value falls on a dB nCL value of 4, 7 or 10, we would recommend using the higher category at first fit and using follow-up appointments to collect your patient’s feedback and adjust accordingly.
The ACT value is designed to support the adjustment of advanced hearing aid features. Please refer to the guidance tab in the software (Figure 1).
You should still perform real-ear measurements. ACT will support you in setting the adaptive features of your client’s hearing aid. Real-ear measurements will support you in prescribing the correct dose of gain for your client.
Yes. Some hearing aids can automatically use the ACT values. With those that can’t, you can make manual adjustments. To help with this, the software provides fitting guidance based on the ACT value (Figure 1).
Yes. The frequency shaping is according to the loss.