My research concerns how sound is transformed from
vibrations to perception, how this process can go wrong and what we can
do about it. I am engaged in several research projects on various
I am currently looking for new students at
both the MSc and PhD levels. Skills that I'm looking for include
a background in optics, hearing sciences, electronics, mechanics,
physiology and/or computer programming.
Send me an email with your CV and transcript to apply.
|This is me next to our very cool 3D laser Doppler vibrometer, the Polytech PS400-3D.
Optical Coherence Tomography of the Ear
Optical coherence tomography is a relatively new imaging technique
that uses a low-coherence interferometer to produce depth-resolved scans in
tissue. I am currently building both free-space and endoscopic OCT
systems for imaging the ear. The free-space system will allow us to look
into the middle ear through the tympanic membrane and the endoscopic system
will look through the round window into the cochlea. To the right
is an example of where we are heading: an image of a cadaveric tympanic
membrane taken with an opthalmic OCT scanner.
High-frequency Ultrasound in the Human Auditory System
In collaboration with Jeremy Brown I have
been working on a variety of
ultrasound-related technologies for use in the human ear.
High-frequency ultrasound is similar to conventional ultrasound but
works at 20-70 MHz instead of the 1-10MHz range of standard
ultrasound. Our group is one of the first to try applying it in
imaging the auditory system, resulting in some beautiful in-vitro
images of different parts of the middle and inner ear.
We are currently working on using ultrasound as a drug-delivery
system for the inner ear, novel approaches to high-frequency
beamforming and opto-acoustic techniques in ultrasound.
We are also looking at how to use new relaxor-PT piezoelectric
materials to push the frequency and resolution of ultrasound imaging
beyond what can be achieved with PZT.
Vibration analysis of the human skull
conducted hearing aids are an effective way
of treating conductive hearing loss, but the physiology of bone
conduction has not received much study. In a series of Laser
Doppler Vibrometry experiments we have completely mapped the 3D
vibrational response of a dry human skull to an applied point
force. As you can see in the videos below, there are three main
regimes of vibration -- quasi-rigid motion below 1000Hz, modal
vibrations between 1000 and 10,000Hz and standing waves above 10,000Hz
16,000 Hz clear wavelike motion can be seen. The waves interfere
to form a characteristic egg carton-like surface in the video above,
but if we look only at motion in the x-direction, clear peaks and
troughs are visible. The waves have all of the properties of
plate bending waves.
With MSc student Carmen McKnight I am trying to understand the
dispersion relationship for waves in the skull and using this data to
establish a better model of how sound propagates in the skull
Powering implanted devices with ultrasound
active implanted hearing devices like cochlear implants are powered
using a pair of coils. A current is driven in the
outer coil and the changing magnetic field in the implanted coil
generates an electromotive force that can drive the device. In
order to be efficient such coils need to be quite large, typically 5 cm
We are looking into using ultrasound as an alternative means of
delivering energy to implanted devices. Unlike magnetic fields,
ultrasound can generated as a focused beam, and a large amount of
energy can be concentrated in a small area. Our devices are only
5 mm in diameter and yet can deliver over 400 mW of power to implanted
devices with efficiency comparable to that of a 5 cm coil.
Hearing and balance aids
|I have built a number of medical devices that we test on patients in
Dr. Bance's clinic. These range from balance aids to help
patients with vestibular loss to localization aids to help patients
with single-sided deafness to identify the locations of sound sources.
hollow external ear transducer (HEET) is a novel bone conduction
hearing aid that fits in the ear canal and vibrates the boney canal
subcutaneous piezoelectric anchored hearing aid (SPAHA) is an impanted
hearing aid that lies flat against the skull unlike the percutaneous
BAHA. This allows skin to heal over the implant which is both
more cosmetic and less prone to infection.
balance belt is an aid for patients with vestibular loss. An
accelerometer constantly measures posture and provides feedback through
vibrating motors located around the belt.
RBA Adamson, M Bance and J A Brown, A
piezoelectric bone-conduction bending hearing actuator, The Journal of
the Acoustical Society of America, vol 128, no 4, pp 2003-2008, 2010
Z Torbatian, R Adamson, M Bance and J Brown, A
split-aperture transmit beamforming technique with phase coherence
grating lobe suppression, Ultrasonics, Ferroelectrics and Frequency
Control, IEEE Transactions on, Vol 57(11), pp 2588-2595, Nov 2010
R Deas, R Adamson, L Curran, F Makki, M Bance and J Brown, Audiometric
thresholds measured with single and dual BAHA transducers: The effect
of phase inversion", Int J Audiol, 49, pp 933-9, Dec 2010
Brown JA, Torbatian Z, Adamson RB, Van
Wijhe R, Pennings RJ, Lockwood GR, Bance ML, High-Frequency Ex
vivo Ultrasound Imaging of the Auditory System, Ultrasound in
Medicine and Biology 2009 Aug 11
(Before staring my post-doc I was a hard-core quantum physics researcher)
Adamson and AM Steinberg, Improving quantum state estimation with
mutually unbiased bases, Phys Rev Lett, vol 105(3), pp 030406, 2010
L. K. Shalm, R. B. A. Adamson and A.M. Steinberg, Squeezing and
over-squeezing of triphotons, Nature 457, 67-70 (01 Jan
R. B. A. Adamson, P. S. Turner and A.M. Steinberg, Detecting
hidden differences via permutation symmetries, Phys. Rev. A 78,
R. B. A. Adamson, L. K. Shalm, M. W. Mitchell, and A. M.
Steinberg, Multiparticle State Tomography: Hidden Differences,
Phys. Rev. Lett. 98, 043601 (2007)
R. B. A. Adamson, L. K. Shalm, and A. M. Steinberg, Preparation
of pure and mixed polarization qubits and the direct measurement of
figures of merit, Phys. Rev. A 75, 012104 (2007)
M.A. Touzel, R. B. Adamson, and A. M. Steinberg, Optimal
bounded-error strategies for projective measurements in
nonorthogonal-state discrimination, Phys. Rev. A 76,