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The Use of Ultrasonic Bone Conduction to Treat Tinnitus

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Title: The Use of Ultrasonic Bone Conduction to Treat Tinnitus


1
The Use of Ultrasonic Bone Conduction to Treat
Tinnitus
  • Josh Vicari
  • July 23, 2007

2
What is Tinnitus?
  • Tinnitus is the perception of sound in the ears
    when no external source is present
  • Typically, it is perceived as a bell-like or
    ringing tone however, some people report hearing
    sounds such as crickets, music, waves or buzzing
  • Many people experience this condition at one
    point in their lives after events such as
    concerts however it usually disappears after
    24-48 hours
  • In severe cases, tinnitus will effect the patient
    24 hours a day, seven days a week
  • Tinnitus Sample

3
What causes Tinnitus
  • Tinnitus is usually caused by a head injury, an
    infection, diseases ranging from the common cold
    to diabetes, or exposure to loud sounds such as
    gunshots and explosions
  • It is estimated that in the United States alone,
    over 36 million people suffer from tinnitus.
    Around 10 million of these people have a severe
    case

4
  • It can also be a sign of hearing loss. People who
    work with loud equipment, such as power tools,
    commonly develop the condition
  • The cochlea contains thousands of tiny hairs
    which vibrate in response to sound waves and
    cells which convert neural signals back into
    acoustical vibrations. The sensing cells are
    connected with the vibratory cells through a
    neural feedback loop, which is regulated by the
    brain. This loop is normally adjusted just below
    the onset of self-oscillation, which gives the
    ear its spectacular sensitivity and selectivity.
    If something changes, it's easy for the delicate
    adjustment to cross the barrier of oscillation
    and tinnitus results.
  • Evidence has been found that the brain reprograms
    its nerve cells based on sensory loss. If the
    brain changes its response as a result of some
    hearing loss, then this could be the cause of
    tinnitus.

5
Current Tinnitus Treatments
  • There are many different forms of tinnitus
    treatments available today for patients ranging
    from herbal remedies to cochlear implants
  • With most methods of treatment, a great deal of
    time and patience is required for the therapy to
    be effective

6
Bone Conduction
  • Conduction of sound through the bones of the
    skull to the inner ear
  • A transducer is used to convert an electrical
    signal into mechanical vibrations
  • Vibrations are conducted through the skull bones
    to the cochlea, which interprets and sends the
    signal to the brain

7
Why Use Bone Conduction?
  • Humans typically cannot hear ultrasound ( gt 20
    kHz) through basic air conduction, but can
    perceive sound at frequencies up to 108 kHz
    through bone conduction
  • It has been suggested that the reprogramming of
    the brain could be reversed with high frequency
    stimulation.
  • Bone conduction has many applications in the
    medical and communications industries such as
    headphones, hearing aids, cell phones, and
    communications systems used in high-noise
    environments

8
The Tests
  • Used Kyma X and the Capybara 320 to run tests
  • Kyma X allows us to adjust sound filters and the
    value of the ultrasonic frequency

9
Amplitude Modulation (AM)
  • Variation of the amplitude
  • of a carrier wave that is
  • multiplied (modulated)
  • with an input signal
  • When the carrier wave is
  • modulated with the input
  • signal, its amplitude varies
  • in the same manner as the
  • input

10
AM in Frequency Domain
  • Frequency components of the input signal are
    reproduced at the carrier frequency

11
The Tests
  • Live input given to subject in sound booth
  • Subject wore headphones which gave clean signal,
    and a transducer which delivered processed signal
  • Objective was to make speech sound as
    intelligible and pleasant as possible so that
    patients will stay with treatment
  • The longer a patient undergoes therapy, the better

12
What We Tried
  • Searched for proper filtering algorithms and
    appropriate value for carrier
  • Multiple Carriers at different values decreased
    intelligibility
  • Placement of Ultrasonic Transducer depends on
    individual
  • Number of Transducers (one vs. two) one was
    easier to understand the two transducers seemed
    to produce an echo or delay within the head

13
Sine Wave vs. Square Wavejar
14
Carrier Suppressiontwins
15
Our Device
16
The Not-So-Secret Part
17
References
  • M. Lenhardt et. al. High Frequency Sound
    Treatment of Tinnitus.
  • 2001. VCU. 22 July 2007. lthttp//www.tinnitus.v
    cu.edu/Pages/ASA01lay.PDFgt.
  • M. Lenhardt et. al. Human Ultrasonic Speech
    Perception.
  • Science. 253, 82-85 (1991).
  • About Tinnitus. 2007. American Tinnitus
    Association. 22 July 2007.
  • lthttp//www.ata.org/about_tinnitus/gt.
  • M. Lenhardt et. al. Tinnitus Improvement with
    Ultra-High-Frequency
  • Vibration Therapy. International Tinnitus
    Journal. 11, 1, 14-22
  • (2005).

18
Acknowledgements
  • Dr. Martin Lenhardt, mentor
  • Alan Madsen
  • Josh Slane
  • Dr. Allison Johnson and the Howard Hughes Medical
    Institute
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