Common model procedures for Germany

The following information describes the status quo in Germany in a rather generalized way. Any individual approach can vary substantially due to different characteristics of hearing deficits and different expectations of the hearing aid.

Hearing aid rehabilitation:

1st appointment: 1-1.5 hours

  • Welcome
  • Take medical history
  • Otoscopy
  • Audiometry: Pure-tone and speech (via headphones)
  • Counselling interview
  • Hearing aid selection
  • Taking ear impression for earmould (if needed)
  • Prescriptive fitting due to pure-tone audiogram

2nd appointment: 45-60 min

  • Checking fit of earmould (optimizing if necessary)
  • First fine tuning
  • Speech audiometry via loudspeakers with and without hearing aid
  • Only if necessery: aided tone audiogram
  • Explaining and training: handling of the hearing aids

3rd appointment (and further appointments, until user is satisfied): 30 min

  • Comparative fitting with different hearing aids
  • Fine tuning
  • Speech audiometry via loudspeakers with hearing aid

Between 2nd and final appointment the hearing aids are tested at home for 1 to 2 weeks.

Final appointment: 1 hour

  • Final speech audiometry
  • Real-ear measurements or loudness scaling (if needed)
  • Fitting documentation
  • Handing out warranty certificates and invoice for hearing aid

Measurements at hearing aid acousticians

  • Pure-tone audiometry: air and bone conduction thresholds, UCL
  • Speech audiometry:
    Headphones: Hearing loss in quiet with numerals (difference individual SRT to normal SRT in dB), intelligibility in quiet with monosyllabic words (in %), UCL for speech (numerals or monosyllabic words)
    Loudspeakers: Intelligibility of monosyllabic words in quiet at 65 dB with and without hearing aid
  • Aided audiogram
  • Real-ear measurements: Open ear gain at 65 or 70 dB; insertion gain (1m distance) at different levels (mostly 50, 65, 80dB); input-output function
  • Loudness scaling
  • Test box: input-output function, gain frequency response at 50, 65, 80 dB

Aim of hearing aid fitting

„The aim of hearing aid fitting could not be globally formulated because of different characteristics of hearing deficits and different expectations of the hearing aid. However, the extensive reconstruction of the ability to communicate should be mentioned in the first place.” (Lehnhart, 2001)

Inexperienced hearing-aid users

Aim: acceptance of hearing aid, therefore fitting based on loudness perception rather than maximizing intelligibility

Theory: 6 point program by Keller - 3 points should be fulfilled for a successful fitting

  1. Maximum intelligibility in quiet with hearing aids should be reached at 65 dB (via loudspeakers)
  2. SRT in quiet (numerals) with hearing aids should be reduced by minimum 10 dB compared to the unaided situation
  3. Maximum intelligibility in quiet should not be less than unaided
  4. Intelligibility functions for monosyllabic words and numerals in quiet should be steeper than unaided and be closer together
  5. Numerals should be tolerated at 90 or 100 dB (via loudspeakers)
  6. Intelligibility function for monosyllabic words in quiet should be monotonically increasing

Practice:

  • Loudness perception
  • Usability of hearing aid
  • One hearing aid: Maximum intelligibility in quiet should be reached at 65 dB (via loudspeakers)
  • Two hearing aids: Intelligibility in noise (monosyllabic words, noise level 60 dB or 40 dB if discrimination loss exceeds 30%, SNR: 5dB) should increase by minimum 10% compared to one hearing aid

Modifications of earmoulds

Vent size:

  • 0.5-0.8 mm: ventilation, pressure equalisation
  • 1.0-1.8 mm: frequency shaping (low cut)
  • 2.0-4.0 mm: high frequency hearing loss (low cut), gain reduction at 500 Hz up to 30 dB
  • If own voice sounds too dull: extending venting
  • Y-vent: vent and sound bore converge; only applied if space is tight

Sound bore profile:

  • Libby horn: diameter increases from 2 mm to 3, 4, or 5 mm: passive amplification of high frequencies up to 15 dB
  • Bakke horn: bracket with diameter increases from 2 mm to 3 mm, sound bore increases to 4 mm: same effect as Libby horn
  • Tubing: diameter 1, 2, or 3 mm: better transmission of high frequencies with increasing diameter
  • Dampers: to be introduce in earhook to reduce resonance peaks; sometimes integrated in special earhook

Material:

  • Acrylic: hard earmould, possibly with anti-allergenic surface coating
  • Silicone: soft earmould, often used for children, but not if often otitis media
  • Thermotec: hard earmould that softens in contact with ear canal.
  • In case of allergies: Gold or titanium

Literature

Lehnhardt, E. (2001), „Praxis der Audiometrie“, 8. Auflage, Thieme, Stuttgart
Voogdt, U. (1998) „Otoplastik“, 2. Auflage, Medion-Verlag von Killisch-Horn GmbH
Jens, U. (2001) Hörgeräte-Akustik, 1. Auflage Documents of Vocational School for Hearing Aid Acousticians, Lübeck
Documents of University of Applied Science Oldenburg, Ostfriesland, Wilhelmshaven, subject hearing technology (Prof. Dr. Holube)

 

The description of common German rehabilitation procedures was given by Hörzentrum Oldenburg GmbH. The description is based on the content of teaching hearing aid professionals in Germany.

 

Read on: Further details of the German pathway or rehabilitation pathway in the Netherlands or UK.