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2 nd International Hearing Loop Conference: Telecoil Panel

2 nd International Hearing Loop Conference: Telecoil Panel. Linda Kozma-Spytek Research Audiologist Technology Access Program Gallaudet University RERC - Telecommunications Access RERC – Hearing Enhancement. amplified. passive. Telecoils.

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2 nd International Hearing Loop Conference: Telecoil Panel

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  1. 2nd International Hearing Loop Conference: Telecoil Panel Linda Kozma-Spytek Research Audiologist Technology Access Program Gallaudet University RERC - Telecommunications Access RERC – Hearing Enhancement

  2. amplified passive Telecoils A telecoil is a coil of wire around a magnetic metal core that is sensitive to magnetic fields. Sensitivity is determined by its: • size and geometry • programming gain (amplification) applied • Amplified Telecoils • consist of a coil and preamplifier • preamp increases sensitivity of the telecoil • should have RF-interference protection Photo used with permission from Oticon, Inc. Approximately 60% of hearing aid fittings in the US include a telecoil, and all cochlear implants have telecoils.

  3. Telecoils are used in hearing devices to connect to: Telephones (directly) • Landline Phones (corded and cordless) • Wireless Devices (basic cell phones, feature phones and smart phones) Hearing Assistive Technology (HAT) • Induction Loop Systems (directly) • Other HATs (FM/IR) via • Neckloops • Silhouettes • Headsets Audio Devices (telephones, music players, etc.) via • Neckloops • Silhouettes • Headsets

  4. Programming • Fully programmable memory dedicated for telecoil use: • amplification characteristics can be independently adjusted by the audiologist, including mixing input from the telecoil and microphone • amplification characteristics can also be preset • (manufacturer default telecoil program) Remote Control Manual: Automatic: Touchless Telecoil

  5. Why use telecoil coupling? • Reduce acoustic background noise in all communication settings (- magnetic noise) • Reduce the effects of poor room acoustics (reverberation) in all communication settings • Reduce the effects of distance (level of the speaker’s voice remains constant regardless of the distance between the hearing aid wearer and the speaker) in settings where the telecoil is part of a hearing assistive technology system (- microphone location) • Eliminate acoustic feedback during telephone coupling

  6. Acoustic Loudspeakers T Induction Loop (IL) System reflected sound noise noise SPEECH SPEECH SPEECH

  7. Telecoil Orientation For best coupling with a telecoil, a magnetic field should cut across all turns in the wire of the telecoil by aligning with the axis of the core. Figures adapted with permission from HyperPhysics by Rod Nave, www.phy-astr.gsu.edu maximum coupling no coupling no coupling maximum coupling

  8. vertical telecoils couple best with the weaker radial (vertical) magnetic field lines of a telephone `` `` horizontal telecoils couple best with axial (horizontal) magnetic field lines of a telephone Magnetic Field Orientation vertical telecoils couple best withthe verticalmagnetic field lines of a room loop

  9. Source Magnetic Field Strengths

  10. Net Frequency Response Magnetic Source Receiver + Telephone Net Frequency Response HA Signal Processing = HA (amplified) telecoil + Induction Loop System

  11. Comparison of Magnetic Frequency Responses for Telephones and Audio Loops

  12. What needs to be considered for telecoil coupling capability? Source (Magnetic) Requirements: • High enough signal strength • Low enough noise/distortion level • High enough signal to noise ratio • Usable field orientations • Large enough coverage area • Appropriate frequency response Receiver (Telecoil) Requirements: • Adequate sensitivity • Low enough noise/distortion level • High enough signal to noise ratio • Usable telecoil orientation • Standard frequency response • System Verification Goals: • To objectively quantify the real-ear performance of the hearing aid in telecoil mode (when coupled to a telephone or hearing assistive technology) in relation to a prescriptive target • Need: Level-controllable standard inductive signal sources

  13. Acknowledgements The contents of this PowerPoint presentation were developed under grants from the Department of Education, NIDRR grant numbers H133E080006 and H133E040013. However, the opinions and content are those of the grantees and do not necessarily represent the policy of the U.S. Department of Education.

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