Hearing Aid Check

Hearing aid checking is a mandatory part of hearing aid fitting. On the one hand, the check of the hearing aids serves to evaluate their technical functionality, i.e., whether the devices behave as desired. On the other hand, it serves to determine the success with regard to the improvement of the patient’s hearing situation. Furthermore, audiometric tests (hearing tests) enable the devices to be optimally adjusted, thus increasing the benefit for the patient. The indication for a hearing aid is previously made by the ENT (ear, nose and throat) doctor. The fitting of the devices is done by the hearing care professional, who is responsible for the following tasks:

  • Advice on additional communication aids
  • Instruction in the use of the devices
  • Aftercare
  • Repair services
  • Services

Finally, an examination is carried out by the ENT doctor, who, among other things, verifies the success of the fitting with the help of a speech audiometric examination (understanding of numbers and words at different volumes). The following text provides an overview of the procedure for a hearing aid check.

Indications (areas of application)

  • Verification of hearing aid function
  • Validation (confirmation) of the success of the fitting for the patient.

Contraindication (contraindications)

There are no absolute contraindications for the hearing aid check, which should be considered an obligatory part of the hearing aid fitting. The patient should be physically fit as well as cooperative for this elective routine examination.

Procedure

A variety of tests and procedures are available for hearing aid screening. Individual tests differ in terms of the level of the auditory system (synonym: auditory system) they examine. The examination of the peripheral auditory system (e.g. auditory canal) is primarily suitable for checking the functionality of the hearing aids, while examinations concerning the central processing of acoustic signals or speech comprehension are more suitable for quantifying the success of the fitting. The following list shows such procedures ordered with respect to ascending auditory processing (that is, from peripheral to central):

  • Coupler measurement – determination of the electroacoustic properties of the hearing aid for technical quality control.
  • Probe microphone measurement – measurement of sound pressure in the peripheral auditory canal as close as possible to the eardrum to determine the acoustically effective gain and thus the transmission quality by the hearing aid.
  • Stapedius reflex measurement* – measurement of the volume that leads to the triggering of the stapedius reflex (reflex that serves as noise protection and reduces the transmission of sound from the eardrum to the ossicles.).
  • Brainstem audiometry (ABR)* – In this examination, electrical signals are derived within the auditory pathway of the brain. From this, conclusions can be drawn about the condition of the patient’s hearing (ABR is performed, if indicated, before prescribing a hearing aid to rule out a so-called retrocochlear disorder, such as that caused by an acoustic neuroma (synonym: acoustic schwannoma; benign (benign) tumor arising from Schwann’s cells of the vestibular portion of the VIIIth cranial nerve, the auditory nerve, the auditory nerve, and the vestibular nerve). Cranial nerve, the auditory and vestibular nerves (vestibulocochlear nerve), and located in the cerebellopontine angle or internal auditory canal)).
  • Sound threshold audiometry* (hearing threshold determination) – determination of the hearing threshold for pure tones (sinusoidal tones) at octave or half-octave intervals (between 125 and 8,000 Hz), that is, the boundary between audible and inaudible sound.
  • Determination of MLC (English : “most comfortable level”) and US (The discomfort threshold represents the transition from “still pleasantly loud” to “too loud”).
  • Loudness scaling – With the help of this examination, the amplification success by the hearing aid can be checked on a frequency-specific basis.
  • Speech audiometry at rest – testing of speech understanding.
  • Directional hearing test
  • Speech audiometry in noise
  • Subjective assessment of the success of care by the doctor and patient.

* These procedures are primarily used before the prescription of a hearing aid.

A special role is given to the speech audiometric examination, since the restoration of speech understanding and thus participation in any kind of communication is the central goal of hearing aid fitting. To this end, the aim is to move maximum speech understanding into the range of normal everyday speech, which is in the level range of about 65 decibels. For the speech audiometric examination at rest, the Freiburger-Eininsilbertest is usually used. This test consists of 20 groups of 20 monosyllables (one-syllable words) each, which are used to examine speech comprehension or discrimination ability. At different test volumes (60, 80 and 100 dB), the test not only determines whether the patient hears something, but also whether he understands the syllables. According to the results, the hearing aids can be adjusted and the hearing quality can be checked. In order to obtain a more realistic method of evaluating speech understanding, speech audiometry is performed in noise: This can be done, for example, with the help of the Oldenburg sentence test (OLSA). The patient is offered sentences as a signal, and at the same time an interfering noise is imparted. The signal-to-noise ratio at which 50% of the words are correctly understood is determined. In addition to such examinations, the fit of the earmold and the patient’s ability to handle it must of course be checked. Furthermore, the recording of the patient’s subjective assessment of the success of the fitting is an elementary part of the hearing aid check. Often the subjective hearing experience differs from objectively measured values, so that a systematic step-by-step fine-tuning is necessary to achieve the optimal treatment success. Depending on the patient’s medical situation as well as the type of hearing aids, the regular check-up of the hearing aids is individually tailored to the patient. Especially in children, regular fitting is of great importance, as hearing ability is directly related to speech development.

Possible complications

No relevant complications are to be expected in the course of hearing aid screening. Only the failure of the hearing aid fitting should be pointed out, so that a reevaluation (reassessment of the findings) of the same is to be expected in the following.