Hearing Enhancement Systems

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Hearing Enhancement Systems

• A presentation by
• John Popplestone
• Connevans Limited

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Hearing Enhancement Systems

• Audio Frequency Induction Loop Systems
• Soundfield Systems
• Personal fm Systems

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How a Hearing Aid works

• Microphone picks up the sound.
• This is amplified through the hearing aid
  circuit.
• Then produced as amplified sound through the ear
  hook and into the earmold.

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The problem using a hearing aid

• Background noise
• Room acoustics

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Why do we use loops or fm Systems?
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Audio Frequency Induction Loop Systems

• Sometime referred to as AFILS more often just
  called loops.
• They operate by generating a magnetic field in
  the area where they are used.
• When the HA is within the magnetic field an
  induced current can be picked up by the telecoil
  in the HA and then amplified by the HA circuit to
  be produced as sound.

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AFILS design considerations

• Getting the wanted sound into the loop system.
• It is not much use just putting a microphone in
  the ceiling and expecting it to be any better
  than just using the HA on its own.
• The microphone needs to be close to the sound
  source.

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AFILS design considerationscont
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AFILS design considerationscont
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AFILS design considerationscont
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AFILS design considerations

• Low overspill designs can allow loops to be run
  side by side but they are more expensive and the
  loop array needs to be positioned under the floor
  covering
• Even with low overspill loops there still needs
  to be vertical separation.

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What size of amplifier do I need?

• The power of the amplifier is dependent on the
  size of the area to be covered.
• Consideration need to be made of the construction
  of the building.
• Metal in the construction can cause losses due to
  absorption of the magnetic field and may also
  require frequency response correction.

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What other factors do we need to consider?

• Are there existing magnetic fields that could be
  picked up on the T setting of the HA.
• These could, amongst other things, be large
  electrical supply feeder cables, heavy duty
  electrical equipment, lift motors, incorrectly
  wired low voltage lighting systems and electrical
  under floor heating.

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Advantages of Loop Systems

• A HA with a T setting does not require any
  other equipment to make use of the Loop System.
• Reduction in unwanted background noise.
• Improved signal to noise ratio.

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Common applications for AFILS

• Lecture Theatres
• Public Performance Venues
• Village Halls
• Meeting Rooms
• Reception Counters
• Bank and Post Office Counters

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Soundfield Systems

• An amplification system which provides an even
  spread of sound round the room.
• It allows all students to hear equally well
  wherever they are seated.

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Soundfield Systems

• Although their prime use is in the education
  setting they are also used in other Public Areas
  such Retirement Homes, Village Halls etc..
• Quite often in this type of environment they are
  also used in conjunction with loop systems but
  not usually in the classroom.

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Soundfield Systems

• The transmission system between the speaker and
  the receiver/amplifier can be either Radio or
  Infra Red.
• There are specifically designed classroom systems
  that incorporate the receiver/amplifier in one
  compact unit.
• For larger hall systems they are usually made up
  of separate components mounted in a rack mount
  cupboard

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Soundfield Systems
A Classroom Soundfield System consists of
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Enhance the Listening Experience
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Benefits the Tutor
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Benefits the student
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Radio based systems are multi channel so up to
about 30 classrooms can be equipped in the same
area.
With Infra Red systems the number is unlimited
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Personal fm Systems

• Usually referred to as Radio Aids.
• They are totally portable and require no
  installation.
• The user has control of the system and takes it
  with them to wherever they need it.

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• Transmitter is worn by the person who is
  speaking.
• The receiver is worn by the listener.
• It can be used with a neck loop, direct
  connection to the hearing aids or with headphones.

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• Basic one to one situation

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• Teaching situations

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• In meetings with a conference microphone

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Summary

• Loop, Infra Red and fm Systems are designed to
  improve the signal to noise ratio, reduce
  background noise and transmit the wanted sound to
  the user.
• Soundfield Systems enhance the listening
  environment and benefit everyone from those
  talking to those who are listening.

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• Thank you for listening.