Range of application of the new AT2000 clinical audiometer
Range of application of the new AT2000 clinical audiometer
AURITEC is setting new standards in clinical audiometry with the AT2000. In this blog, AURITEC CEO Jan Mody explains what you can look forward to.
In the following blog entries, I will regularly report on the scientific background to this development, for example, and then explain the situations that our customers have described to us, which they are facing and which they hope we can solve. In further episodes, I would like to discuss possible set-ups that you can implement with the AT2000 audiometer and that could help you in your clinical routine. I will show you which common speech procedures are already available for multi-channel applications and then go into more detail on the interaction between direct implant connection and multi-channel capability.
My aim in these articles is to show you these new ways and encourage you to think about what can be done with them in your profession. After all, these possibilities did not exist before, and I am convinced that we will find many new applications together.
The background – What measurements are required for optimal cochlear implant care?
The S2k guideline on cochlear implant treatment from the German ENT Society states that the audiological follow-up of CI systems includes speech tests at quiet and in noise at defined checkpoints. And when CI processors are upgraded, the gain with the new processor should be documented, and the gain is also based "on the improved hearing performance in quiet and in background noise before and after the implantation".
For bilateral testing of CI systems, the DGA recommends speech audiometry in noise with a suitable speaker arrangement as a necessary measure as part of basic therapy. And since these two requirements coincide with developments in processors that aim to identify "good" and "bad" sound, it is clear that it‘s difficult to prove to the payer that hearing performance has improved using conventional measurement methods. In order to provide this proof, the pendulum must swing from the clinical environment to everyday situations with a higher ecological validity. Patients benefit from a fitting that is closer to everyday life and the cost bearers can be shown the benefit so that the costs are reimbursed. And when these two points are met, YOU are satisfied. So our goal was clear.
Episode 2
Challenges and possible solutions – paradigm shift in the measurement of speech intelligibility in noise?
The procedure used by our customers to demonstrate the improved participation in life required in the sense of being on a par with a hearing-impaired person is very heterogeneous. The majority of them perform speech comprehension tests in quiet with the Freiburg number- and word Test at various levels, S0 in each case; and OLSA measurements in noise with S0N0, in each case with the previous processor and later with the new one (this part of the process is similar before the initial implantation). When examining speech comprehension in quiet with the Freiburg words, an increasing number of patients are already in the saturation range of the test, i.e. no gain in speech comprehension can be demonstrated here with a new speech processor.
And even in the clinically established measurement set-up for examining the gain in speech understanding in noise, new technologies in current speech processor models often do not show any improvements (any more). This can be explained by the fact that new signal pre-processing methods are aimed in particular at improving speech understanding in everyday situations with background noise, which tend to be characterized by spatially separated signal and background noise sources. These programs include, for example, "Natural", "ANR" and "TNR" from MED-EL or "ForwardFocus" from Cochlear.
In our opinion, the solution is to measure speech intelligibility in background noise with several loudspeakers so that the gain from new signal pre-processing can be better reproduced in everyday situations with background noise. The number of noise sources and the type of noise are open to discussion, but certainly also depend on the type of noise suppression used by the processor.
But does this mean a paradigm shift, at least in part? Does S0N0 need to be supplemented by several measurement setups suitable for the processors and their different signal pre-processing components? If the answer to this question is "yes", an audiometry system is needed that can switch quickly and flexibly between these measurement setups. After all, this question leaves the realm of science and enters clinical routine. What is needed is an audiometry system with more than 2 channels, established test procedures that are based on more than 2 channels and transducers that can be used flexibly in terms of type (AC, BC, Inserts, FF) and directions (freefield).
Episode 3
Test procedure – What are the advantages of multi-channel audiometry?
With the AT2000, AURITEC can now offer you an audiometry system whose hardware is capable of playing back more than 2 different signals simultaneously (in the case of FF also from different directions). In the software, we have also created the prerequisites for you to be able to react flexibly to the different signal pre-processing strategies in order to be able to demonstrate the gain in speech intelligibility. For this reason, you can also use different signals such as "Fast Road", "Party Noise", "ISTS" and others. This should make it possible to "measure" many new signal preprocessings. (Fig. 1)
But even if you do not want to compile a test yourself - such a series of measurements can of course be saved and used again at any time - the multi-channel capability of the AT2000 will help you. The Hearing Center in Oldenburg has developed the widely used OLSA with up to 4 channels, and the AT2000 is the first audiometer to bring this configuration from the research variant into clinical routine. (Fig. 2)
With the test, the procedure remains the way you know it, but you now have the option of selecting more channels in the settings and a larger selection of background noises is possible.
With both test methods, it is therefore possible to create a more ecologically valid environment with several noise signals played simultaneously. I assume that this will make it easier to demonstrate improved hearing performance through fitting or re-fitting than before. The scientific articles that I have read on this are:
Hey M, Mewes A, Hocke T. Speech comprehension in noise—considerations for ecologically valid assessment of communication skills ability with cochlear implants. German version. HNO. 2022; doi:10.1007/s00106-022-01234-1.
Baumann U, Weissgerber T, Stöver T. Speech perception in noise : Impact of directional microphones in users of combined electric-acoustic stimulation. 2019;
Kurz A, Rak K, Hagen R. Improved performance with automatic sound management 3 in the MED-EL SONNET 2 cochlear implant audio processor. PLoS One. 2022; doi:10.1371/journal.pone.0274446.
(Fig. 1)
(Fig. 2)
Episode 4
Arrangement of the speaker – Which setup for precise audiometry?
In Germany, the Mainz children's table has been the established set-up for pediatric audiometry for decades. This is the standard in most other countries where no single set-up has become established. The Mainz pediatric table has the advantage that the distance of the loudspeakers to the patient and the distance of the individual speaker around the patient is usually uniform, i.e. the speaker membrane is 1 m away from the patient's head and the speakers are arranged at a distance of 45° around the patient with one speaker at 0° directly in front of the patient.
This setup helps with all patients today: Children and adults. We therefore do not need different setups, but can test all patients together on one setup (given the table is height-adjustable so that the speakers can be easily moved to the height of all patients' ears).
AURITEC also has a fixed holder for 3 speakers (on castors) for the rear hemisphere, so that we can supply 8 speakers at 45° angles. In recent scientific publications, the interference signals from behind are set up in exactly the same way (see Kurz. et al. 2022).
Episode 5
Speech audiometry in noise in SSD patients – Which masking options for CI patients?
To evaluate treatment success with implant patients, the binaural gain in intelligibility with implant is measured, and this results from the binaural summation, see previous newsletter. This is especially true for AHL/SSD patients. It also makes sense to perform speech audiometry monaurally with CI, because the discrimination function also provides information that can be used to optimize the setting of the C- and T-levels. For example, it appears that the setting of the T-levels mutually influences the speech intelligibility threshold in quiet and in noise and must therefore be balanced. With monaural measurement of speech intelligibility thresholds in quiet and in noise with CI in the free field, however, there is a risk of overhearing in the case of asymmetrical hearing loss and especially in the case of SSD. This is why masking is necessary.
AURITEC now offers two ways of tackling this issue: as Williges et al. have shown, active masking with an additional noise is superior to passive attenuation. He did this with different levels of a second audiometer. With the AT2000 and the AT-research, this is now possible with a single audiometer, and the user can choose the transducer (AC, inserts, FF), the signal and the level. From this Freiburg study, it appears that with OLSA in noise, active masking with noise from a masking level of 60dB can sufficiently reduce the possibility of the good ear hearing something.
In addition to this active masking of the opposite ear, there is an even more direct way: you can measure the monaural speech intelligibility threshold in noise with an implant using a direct radio or cable connection between the audiometer and the CI speech processor. The challenge here is that it must be ensured for the various speech processors that both speech and noise signals are presented at the correct level, which requires very detailed calibration measurements. So far, AURITEC has performed these for 2 speech processors.
So you can now measure all AHL/SSD patients more accurately with the AT2000, either with active masking of the opposite ear or directly via the processor.
The scientific articles that I have read on this are:
Mewes A, Hey M. Einfluss der T-Level auf das Sprachverstehen in Ruhe und im Störschall bei erwachsenen CI-Patienten. Conf Pap Zwanzigste DGA-Jahrestagung, Aalen. 2017;
Volpert S, Klenzner T, Jansen N, Blümel I, Schipper J. Sprachtest bei CI-Trägern ohne Hörkabine? Forsch heute – Zukunft morgen. 2018; doi:10.1055/s-0038-1640666.
Williges B. Evaluation der binauralen und monauralen Sprachverständlichkeit sowie des Lateralisations- und Lokalisationsvermögens von einseitig ertaubten Patienten mit einem Cochlea Implantat. 2012;
Dziemba OC, Oberhoffner T, Müller A. OLSA level control in monaural speech audiometry in background noise for the evaluation of the CI fitting result. HNO. 2023; doi:10.1007/s00106-022-01251-0.
Jan Mody
Jan Mody is the managing partner of AURITEC. Together with his team, he has been working on the continuous further development of the Hamburg-based company's products since 2007. Maintaining the quality standards in clinical audiometry that have been in place for 30 years is always a priority for him.
