University of Edinburgh
 

Audiology Update

Presented on Thursday, 25 November 2010

Options Available

  1. Hearing aids
  2. FM
  3. Soundfield
  4. Seating position

1. Hearing Aids

Multiple programmes

  • Different listening environment, different programme
  • FM and nomic
  • Transition through programmes

Microphones

  • Need to consider which sort of microphone use is best
  • Omni-directional - all around
    • simulates normal hearing experience
    • so good for those learning to listen
    • important for safety factors

Directional-like 'torch beam'

  • Directional or zoom designed for maximuym intelligibility of speech over other noise sources, eg; dishes, music above 70 dB SPL, restaurants, social gatherings, wind noise, car noise, supermarkets
  • Amplification of sibnal from front and systematic reduction of signals from other directions

Assumptions

  • User looking at speaker
  • Signals from the other directions are considered noise

Adaptive Microphones

  • Some of the hearing aids on the NHS contract have devices that adapt to the listening environment.
  • many of the hearing aids on contract have adaptive directional microphones. klThis means that the aid switches between omni-directional and directional mode depending on the relative direction of speech and noise.

Noise reduction algorithms

  • Digital noise-reduction algorithms examine the combined signal and noise waveform after the two have been mixed at the hearing aid input.
  • Decisions are made as to which parts fo the mixture are mostly signal and which parts are mostly noise.
  • The former are preserved while the latter are suppressed.

2. FM

Why use an FM system?

"The basic function of a personal FM system is to enable the user to detect as many sounds as possible by bypassing unfavourable room acoustics and loss of energy with distance." (Berg, 1993 p 118)

  • Distance - 6 dB
  • Noise
  • To compensate for speaker movement
  • To improve S/N ratio

3. Soundfield

LIFE-UK Listening Inventories for Education UK version

  • LIFE UK were developed in 1998 to be used during a national trial of Classroom Soundfield Amplification.
  • The LIFE UK inventories are a modified form of the LIFE inventories created by K Anderson and J Smaldino (can be purchased from the US EAA website).

The original aims of the LIFE questionnaire were:

  • provide a student self-report measurement tool to identify classroom situations which present a listening challenge for an individual student,
  • provide a valid and reliable measurement tool which could be used in a pre-test and post-test format to document the effectiveness of intervention utilised to improve the classroom listening environment.

Examples of LIFE Pupils (Primary)

examples

examples

LIFE UK in Resourced Provision for the deaf child in mainstream class

Click on thumbnail to expand
schematic

examples