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Title: The equivalent noise level generated by drilling onto the ossicular chain as measured by laser Doppler
vibrometry: a temporal bone study

Article Type: Original Study

Section/Category: Otology

Keywords: middle ear surgery, acoustic trauma, noise induced hearing loss, laser Doppler vibrometry,
surgical drill

Corresponding Author: Dr. Alec Fitzgerald O’ Connor, FRCS

Corresponding Author's Institution: Guy’s and St. Thomas Hospitals, London, UK

First Author: Dan Jiang, Ph.D FRCSI(Otol) FRCS(ORL_HNS)

Order of Authors: Dan Jiang, Ph.D FRCSI(Otol) FRCS(ORL_HNS); Athanasios Bibas, MSc DM
FRCS(Otol.) ; Carlo Santulli, Ph.D; Neil Donnelly, MSc MRCS; George Jeronimidis, Ph.D; Alec Fitzgerald
O’ Connor, FRCS

Manuscript Region of Origin:

Abstract: Background: Inadvertent drilling on the ossicular chain, usually in the region of the short process
of the incus, has been regarded as one of the causes of sensorineural hearing loss that may follow
tympanomastoid surgery. Post-operative high frequency hearing loss is more frequently observed than low
frequency hearing loss. It is therefore speculated that hearing loss is caused by vibration of the ossicular
chain that resembles acoustic noise trauma. It is generally considered that using a large cutting burr is more
likely to cause damage than a small diamond burr, although the mechanism of drill induced hearing loss is
poorly understood. Laser Doppler vibrometry allows a no mass measurement of ossicular chain
micromovement.

Aim: The aim was to investigate the equivalent noise level and its frequency characteristics, generated by
drilling onto the short process of the incus in fresh human temporal bones.

Methods and Materials: Five fresh cadaveric temporal bones were used. Stapes displacement was
measured using laser Doppler vibrometry during short drilling episodes. The vibratory stimulus for each
episode was achieved by engaging the burr on the postero-lateral surface of the short process of the incus.
Diamond and cutting burrs of different diameter (1 mm, 2.3 mm and 3.1 mm) were used for the study. The
effect of the drilling on stapes footplate displacement was compared with that generated by an acoustic
signal. The equivalent noise level (dB SPL eq) was thus calculated.

Results: The equivalent noise levels generated by drilling on the incus ranged from 93 - 125 dB SPL eq.
For a 1 mm cutting burr, the highest equivalent noise level was 108 dB SPL eq, whilst a 2.3 mm cutting burr
produced a maximal level of 125 dB SPL eq. Diamond burrs generated less noise than their cutting
counterparts, with a 2.3 mm diamond burr producing a highest equivalent noise level of 102 dB SPL eq. The
energy of the noise increased at the higher end of the frequency spectrum, with a 2.3 mm cutting burr
producing a noise level of 105 dB SPL eq at 1 kHz and 125 dB SPL eq at 8 kHz. In contrast, the same sized
diamond burr produced 96 dB SPL eq at 1 kHz and 99 dB at 8 KHz.

Conclusion: This study suggests that drilling on the ossicular chain can produce vibratory force that is
analogous with noise levels known to produce acoustic trauma. For the same type of burr, the larger the
diameter the greater the vibratory force, and for the same size of burr, the cutting more than the diamond
burr. The cutting burr produces greater high frequency than lower frequency vibratory energy.

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Jiang et al. Drill and Noise

The equivalent noise level generated by drilling onto the ossicular chain
as measured by laser Doppler vibrometry: a temporal bone study

Dan Jiang Ph.D FRCS(Otol) FRCS(ORL-HNS)1, Athanasios Bibas MSc DM FRCS(Otol) 3, Carlo
Santuli Ph.D2, Neil Donnelly MSc MRCS1, George Jeronimidis Ph.D2, Alec Fitzgerald O’ Connor
FRCS1

1. Auditory Implantation Centre, Department of Otolaryngology, Head and Neck Surgery,
Guy’s and St. Thomas Hospitals, London, UK

2. Centre for Biomimetics, School of Construction Management and Engineering,
University of Reading, UK

3. Department of Otolaryngology – Head & Neck Surgery, Hippokrateion Hospital,
University of Athens Medical School, Athens, Greece

Acknowledgment: This research was funded by Guy’s Hospital Charitable Foundation Trust

Corresponding author:

Mr. A. Fitzgerald O’Connor FRCS
Department of Otolaryngology, Head and Neck Surgery
St. Thomas Hospital
Lambeth Palace road
London SE1 7EH UK
Tel: 00442071887188
email: [email protected]

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Jiang et al. Drill and Noise

Abstract

Background: Inadvertent drilling on the ossicular chain, usually in the region of the
short process of the incus, has been regarded as one of the causes of sensorineural hearing
loss that may follow tympanomastoid surgery. Post-operative high frequency hearing
loss is more frequently observed than low frequency hearing loss. It is therefore
speculated that hearing loss is caused by vibration of the ossicular chain that resembles
acoustic noise trauma. It is generally considered that using a large cutting burr is more
likely to cause damage than a small diamond burr, although the mechanism of drill
induced hearing loss is poorly understood. Laser Doppler vibrometry allows a no mass
measurement of ossicular chain micromovement.

Aim: The aim was to investigate the equivalent noise level and its frequency
characteristics, generated by drilling onto the short process of the incus in fresh human
temporal bones.

Methods and Materials: Five fresh cadaveric temporal bones were used. Stapes
displacement was measured using laser Doppler vibrometry during short drilling
episodes. The vibratory stimulus for each episode was achieved by engaging the burr on
the postero-lateral surface of the short process of the incus. Diamond and cutting burrs of
different diameter (1 mm, 2.3 mm and 3.1 mm) were used for the study. The effect of the
drilling on stapes footplate displacement was compared with that generated by an
acoustic signal. The equivalent noise level (dB SPL eq) was thus calculated.

Results: The equivalent noise levels generated by drilling on the incus ranged from 93 –
125 dB SPL eq. For a 1 mm cutting burr, the highest equivalent noise level was 108 dB

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Jiang et al. Drill and Noise
SPL eq, whilst a 2.3 mm cutting burr produced a maximal level of 125 dB SPL eq.
Diamond burrs generated less noise than their cutting counterparts, with a 2.3 mm
diamond burr producing a highest equivalent noise level of 102 dB SPL eq. The energy
of the noise increased at the higher end of the frequency spectrum, with a 2.3 mm cutting
burr producing a noise level of 105 dB SPL eq at 1 kHz and 125 dB SPL eq at 8 kHz. In
contrast, the same sized diamond burr produced 96 dB SPL eq at 1 kHz and 99 dB at 8
KHz.
Conclusion: This study suggests that drilling on the ossicular chain can produce
vibratory force that is analogous with noise levels known to produce acoustic trauma.
For the same type of burr, the larger the diameter the greater the vibratory force, and for
the same size of burr, the cutting more than the diamond burr. The cutting burr produces
greater high frequency than lower frequency vibratory energy.

Key words: middle ear surgery, acoustic trauma, noise induced hearing loss, laser
Doppler vibrometry, surgical drill

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Jiang et al. Drill and Noise

Introduction

The risk of deterioration to hearing on the operated ear is one of the most commonly
discussed issues when consenting patients for middle ear surgery. The incidence of a
permanent sensorineural hearing loss following tympanomastoid surgery is 1.2 – 4.5%1,2,
and higher in cases of congenital malformations, and cholesteatomatous ears with intact
ossicular chain3. Multiple factors may be involved, including drill induced acoustic
trauma of the cochlea, excess manipulation of the ossicles, perilymph fistula and
inadvertently touching the ossicles with a rotating burr.

The possible contribution of drill-generated noise during mastoid surgery to postoperative
sensorineural hearing loss has generated a lot of discussion in the literature, with reported
results that are often controversial. The amount of energy transmitted to the cochlea
should depend on the noise levels produced and the duration of exposure. Various studies
using sound recording techniques have shown that mastoid drilling can produce noise
levels exceeding 100 dB (A)4,5,6. Noise levels are higher with larger diameter burrs, and
with cutting rather than diamond burrs. Rotation speed and site of drilling do not seem to
influence the noise levels4.

Although temporary threshold shifts have been observed during drilling in both animal
and human studies7,8, it is doubtful whether the noise levels produced can lead to
permanent sensorineural hearing loss, unless the ossicular chain is engaged9,10. This
notion is supported by the finding that very few patients who have undergone middle ear
surgery suffer from sensorineural hearing loss in the contralateral ear11, despite the
attenuation of the vibration across the skull being negligible.

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Jiang et al. Drill and Noise
Few studies have focused on the consequences of drilling on the ossicular chain itself12,13.
Current literature is also lacking on the relationship between the type and size of burr
used and the induced vibration frequency characteristics of the stapes. In this study, laser
Doppler vibrometry was used to characterise stapes movement induced by drilling onto
the short process of the incus in fresh human temporal bones. The effect of this drilling
on stapes footplate displacement was compared with that generated by an acoustic signal.
An equivalent noise level was then calculated for different burr types and sizes.

Materials and Methods

Some general aspects of our materials and methods have been published elsewhere14.
Specifics relating to the current experiment are highlighted.

1. Temporal bone harvesting and preparation

The experiments were carried out in five adult cadaveric human temporal bones. Each
bone was obtained within 24 hours of death and was immediately placed in a deep freezer
at -20oC. The appropriate guidelines and procedures for obtaining human tissues were
followed. All experiments were completed within 2 months of death. Bones were
defrosted at room temperature and immersed in normal saline for 1.5 hours before any
measurement was taken15.

A cortical mastoidectomy and posterior tympanotomy was performed in each bone. The
annulus and facial nerve were kept intact to preserve anatomical integrity. The incudal
fossa was opened to expose the short process and entire body of the incus without

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Jiang et al. Drill and Noise

damaging the ossicular chain or anterior attic wall. The ossicular chain and the middle ear
were then examined carefully for any abnormality. All bones were thoroughly rinsed with
normal saline solution to remove bone dust and debris generated by drilling and every
hour thereafter during the experiment to maintain the tissue moisture.

2. Measurement system

The measurement system is shown in Figure 1. It consists of 3 parts; a vibration damping
recording platform, a sound delivery and calibration system, and an operating microscope
mounted laser Doppler vibrometry system.

In order to measure baseline stapes displacement and to provide a term for comparison, a
continuous pure tone stimulus was digitally synthesized using the Vibsoft software and
was outputted to a digital-analog converter at levels from 100 dB SPL. The sound was
delivered through an ER-2 earphone (Etymotic Research) coupled to the ER1-14A ear
tips (Etymotic Research) which was inserted into the ear canal. To generate a middle ear
transfer function, tones with frequencies ranging from 0.1 to 10 kHz with 5 intervals per
octave in a logarithmical scale were used. The output was calibrated 2-3 mm from the
tympanic membrane using an ER-7C probe microphone (Etymotic Research), which was
also incorporated within the ER1-14A ear tips with an ER7-14C probe tube. The ER-7C
probe microphone was calibrated against a standardised calibrator at the beginning of
each experiment.

A commercial hearing laser vibrometer (HLV-1000 Laser Doppler Vibrometer System,
Polytec), mounted over the lens of an operating microscope, was used to measure stapes
footplate velocity. The helium-neon laser beam was focused on the head of the stapes

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Jiang et al. Drill and Noise

through the posterior tympanotomy, without using reflective paint. The reflected signal
was detected and decoded by the vibrometer controller to produce an output voltage
proportional to the stapes velocity. As we aimed to simulate surgical operating
conditions with the least possible interruption of middle ear anatomy, no extra access for
the laser beam was made other than the posterior tympanotomy. The laser beam was thus
not perpendicular to the plane of the stapes footplate. The assumed angle between the
laser beam and a line perpendicular to the stapes footplate was between 20o and 50o. This
would lead to a maximum of 4 dB SPL difference between measured and actual stapes
velocity, and hence only uncorrected values are reported.

3. Drilling noise measurements

Diamond burrs and cutting burrs of different diameters (1 mm, 2.3 mm and 3.1 mm) were
used for the study. An example of a cutting burr and a diamond burr of diameter 2.3 mm.
are shown in Figure 2. Each burr was mounted on the hand piece of an electric drill
(KaVo, 10A, KaVo Dentale Medizinische Instrumente). The rotation speed was between
16000 and 25000 rpm, as per usual clinical practice, and constant in each episode of the
experiment.

The drilling episode was simulated by the surgeon holding the hand piece and lightly
touching the side of the burr to the lateral surface of the body of the incus. The contact
time was 10 seconds. Each bone only underwent two drilling episodes in order to
minimize the potential damage to the ossicular chain. Care was taken not to put any
pressure on to the incus. The whole process was performed under the microscope and an

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Jiang et al. Drill and Noise

attempt was made to standardize the pressure applied, although this was not quantified.
The stapes velocity was measured with laser vibrometer during the drilling.

4. Data collection and analysis

The data acquisition was automated using VibSoft© by Polytec software. The stapes
velocity was converted into peak-to-peak displacement (nm). The signal to noise ratio
for data inclusion was 10 dB. A Fast Fourier transform was performed for the drilling
induced stapes velocity data to obtain frequency information.

To facilitate discussion, the stapes displacement occurring during the drilling is also
expressed as decibels, namely the equivalent noise level (dB SPL eq). This was
calculated using Equation 1, where dexp is the root mean square (RMS) of the
displacement over a certain frequency bandwidth. dref is the reference displacement taken
from the middle ear transfer function of 100 dB SPL at the corresponding frequency.
Each bone served as its own control in this study, i.e. the stapes displacement induced by
drilling was compared with the stapes displacement in response to sound stimulus in the
same bone.

δ dB  100  20 log 10 d exp Equation 1
dref

The frequency specific noise level was calculated within a bandwidth of one third octave
around 500 Hz, 1, 2, 4 and 8 kHz for each burr used.

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Jiang et al. Drill and Noise

Results

1. Standard middle ear transfer functions

The middle ear transfer function was obtained for each of 5 temporal bones and is shown
in Figure 3. The peak to peak displacement of each bone in nm is plotted against
stimulus frequencies at an iso-level of 100 dB SPL. All 5 bones have a similar transfer
function with a relatively flat response up to 1000 Hz. The peak response of each bone is
between 1000 and 2000 Hz, with a decline of the displacement from 2000 Hz upwards.
The characteristic of the transfer function and variations among bones tested are
comparable with other published data including our previous published data14. The
transfer function of each bone was used to calculate the equivalent noise level induced by
burring of the body of the incus.

2. Equivalent noise level induced by burring the ossicles

An example of the response of the stapes to drilling with a 1 mm and 2.3 mm cutting burr
from one temporal bone is shown in Figure 4. The stapes response, expressed in peak to
peak displacement, was plotted against frequency. The middle ear transfer function of
the bone is plotted for reference. The frequency characteristics of stapes vibration
resembles the response to noise, with multiple identifiable peaks from 1 kHz up to 8 kHz.
Note that the 2.3 mm cutting burr appears to produce more such peaks at 4 kHz to 8 kHz.

To investigate the equivalent noise level across frequency range, the frequency related
equivalent noise levels were obtained by averaging displacements (RMS) induced by
burring within a bandwidth of one third octave around 500 Hz, 1, 2, 4, 8 kHz for each

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Jiang et al. Drill and Noise

burr tested. They were then compared with the standard middle ear transfer function at
those frequencies in the temporal bone concerned. Results for 1 mm burrs are shown in
Figure 5. When the 1 mm diamond burr was used, the highest equivalent noise level was
102 dB at 4 kHz. The across frequency variation was 9 dB (93 – 102 dB). A 1 mm
cutting burr produced a highest equivalent noise level of 108 dB at 8 kHz, with the across
frequency variation of 12 dB (96 – 108 dB). The difference in equivalent noise level
between cutting and diamond burrs ranged from 1 dB at 4 kHz to 9 dB at 8 kHz (Mean =
4.6, SD = ± 2.97 dB). Although there is a trend of an increased equivalent noise level
when a cutting burr is used, such a difference is short of a statistical significance (student
t test, P>0.05).

The trend became more obvious when 2.3 mm burrs were used (Figure 6). A 2.3 mm
cutting burr produced an equivalent noise level of 125 dB at 8 kHz in contrast to its
diamond counter part which produced a 99 dB equivalent noise level at same frequency.
Indeed, the equivalent noise level difference between cutting and diamond for 2.3 mm
burr ranged from 6 dB at 0.5 kHz to 26 dB at 8 kHz (Mean = 14.6, SD = ± 7.76 dB,
student t-test, 0.01<P<0.05).

Another observation was that cutting burrs generated higher equivalent noise levels at
higher frequencies. The equivalent noise level differences between 1 kHz and 8 kHz
were 12 dB and 20 dB for 1 mm and 2.3 mm cutting burrs respectively.

Increasing from a 1 mm to 2.3 mm diamond burr only slightly increased equivalent noise
levels, with averaged 5 frequency noise levels of 97 dB for the 1 mm diamond burr and
98.8 dB for the 2 mm diamond burr. The averaged 5 frequency noise level was 110 dB

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Jiang et al. Drill and Noise
for the 3.3 mm diamond burr (Figure 7). The 3.3 mm diamond burr produced less
equivalent noise level at higher frequencies than 2.3 mm cutting burr (Figure 7).

It is noted that the equivalent noise level was slightly higher at 500 Hz than it was at 1
kHz in all five burrs tested.

Discussion

Although it is well established that drilling on the mastoid bone can produce ambient
noise exceeding 100 dB, the majority of studies failed to demonstrate any permanent
sensorineural hearing loss, even after significant drilling9,10, 11. In contrast, inadvertent
injury to the ossicular chain during mastoid surgery is regarded as a major cause of post-
operative permanent sensorineural hearing loss. The anatomical location of the short
process of the incus makes it most susceptible to drill induced trauma.

In a guinea pig model, Gjuric and his colleagues used electrocochleography to evaluate
hearing loss caused by a standardized drill-induced injury to the body of the incus16. In
their study, a 1.4 mm diamond burr at a rotation speed of 20,000 rpm was applied to the
body of the incus for 10 seconds. A threshold shift was observed within seconds, and
after 15 minutes, it averaged 35.7 dB for clicks, 35 dB nHL for 4 kHz bursts, 36.7 dB
nHL for 6 kHz bursts and 39 dB nHL for 8 kHz bursts. This threshold deterioration
remained stable throughout the 5-week post-operative observation period. They found
that simple disarticulation of the incudostapedial joint prior to drilling did not reduce the
degree of threshold shift.

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Jiang et al. Drill and Noise

Paparella showed in cats that engaging a 4-mm cutting burr to the body of the incus
resulted in injury to the Organ of Corti in the basal turn12. The histopathological findings
included disruption of the cyto-architecture with varying degrees of cellular degeneration,
most severe in the outer hair cells. These findings are consistent with the
histopathological changes observed in the noise induced sensorineural hearing loss. In
this study, auditory behavioral testing revealed an average hearing loss of about 30 dB in
3 animals and a 55 dB loss in a fourth. However, a 0.5 mm cutting burr placed on the
long process of the incus failed to produce a cochlear injury.

Seki et al reported the effects of drill-induced damage to the auditory ossicles on the
permeability of the stria vascularis blood vessels in a guinea pig study17. Using infused
horseradish peroxidase they observed increased blood vessel leakage, which significantly
increased in relation to the duration of the drilling injury. The damage to intermediate
cells also tended to be related to the duration of the stimulus.

There are only a few studies looking at the effect of touching the ossicular chain with a
rotating burr upon stapes vibration. Helms found that touching the intact ossicular chain
with a rotating burr produced pressures conducted to the stapes footplate comparable to
130 dB SPL13. Pau and his colleagues showed that contacting the tympanic membrane
with the drill can cause a vibration comparable to 150 dB SPL18. No information on the
frequency characteristics of the vibration was derived from these studies.

In the current study, instead of using a peak displacement to represent the noise level
generated by burring on the incus, we used an averaged equivalent noise level (RMS
level) over a certain frequency range which resembled an effective bandwidth of the

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Jiang et al. Drill and Noise

human cochlea at a particular frequency. By doing so, it allows us to calculate the mean
energy delivered into a specified load (inner ear). Although these levels are lower than
the snap shot of the maximal equivalent noise level which is represented by the largest
gap between a stapes displacement curve in response to burring at the ossicle and the
middle ear transfer function (Figure 4). They would give us a more realistic view of what
may happen when the incus is inadvertently engaged by a rotating burr. Our results
suggest that inadvertent drilling on the ossicular chain can produce vibratory forces that
would be analogous to noise levels known to produce acoustic trauma. In practice, the
equivalent noise level and its frequency may be affected by multiple factors other than
those investigated in this study. These include the speed of the burr and the force of the
engagement, which may also be affected by the torque of the drill7,19. If such levels of
vibration take place at higher frequencies, even a short duration of exposure could induce
significant acoustic trauma20.

One of the principal factors affecting the noise level during drilling is the diameter of the
burr, with the larger diameter burr producing greater vibratory force. This effect is
particularly obvious with the use of a cutting burr. Increasing the size of a diamond burr
from 1mm to 2.3 mm did not significantly increase the equivalent noise level, although a
further increasing to 3.1 mm did result in higher noise levels across all frequencies. In
contrast, the larger the cutting burr from 1 mm to 2.3 mm produced a significant increase
in noise level at all frequencies. One cause for this increase in noise level could be due to
contact area between the burr and the incus, with more energy being transmitted to the
ossicular chain through a larger contact area.

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Jiang et al. Drill and Noise

The present study demonstrates that cutting burrs produce greater vibratory force than
diamond burrs of the same sizes. It has been suggested that the increased skipping and
bouncing of cutting burrs with respect to diamond burrs would produce other
unpredictable vibrations, varying with each drilling episode, and potentially more damage
to the inner ear. Our results also show more vibratory energy being distributed at high
frequencies, and such distribution being more pronounced for cutting burrs. This may
explain the fact the hearing loss observed in clinical studies of mastoid surgery is more
pronounced at higher frequencies.

Is it possible to prevent acoustic trauma related to accidental engagement of the burr on
the ossicular chain? As mentioned above, simple disarticulating the long process of the
incus does not appear to offer any protection in animal studies. Two studies that have
investigated the possible prophylactic effects of steroids are worth mentioning. In a
placebo-controlled, randomized, blinded study, intra-peritoneal injection of methyl-
prednisolone in guinea pigs showed no protective effect in reducing or improving the
auditory threshold shifts caused by drill-induced injury to the body of the incus21. In
another guinea pig study, intratympanic injection of methyl-prednisolone significantly
improved drill-induced sensorineural hearing loss as measured by otoacoustic
emissions22. Other studies have showed some promising results with oral magnesium
supplements and calcium antagonist drugs23.

Conclusions

This study confirms that inadvertent burring on the ossicular chain does produce
vibratory forces that are analogous with noise levels known to produce acoustic trauma.

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Jiang et al. Drill and Noise
For the same type of burr, the larger the diameter the greater the vibratory force
generated, and for the same size of burr, the effect is greater for a cutting than a diamond
burr. Cutting burrs produces more high frequency than lower frequency vibratory
energy. Caution is therefore mandatory during drilling around an intact ossicular chain to
avoid a permanent sensorineural hearing loss as disarticulation of the incudostapedial
joint prior to drilling may have no protective value.

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Jiang et al. Drill and Noise

Figure legend

Figure 1: Schematic illustration of measuring system.

Figure 2: A: a cutting burr. B: a diamond burr. Five burrs were tested: 1 mm and 2.3
mm cuttings; 1 mm, 2.3 mm and 3.1 mm diamond.

Figure 3: Middle ear transfer function at 100 dB SPL of five cadaver temporal bones
used for the study.

Figure 4: An example of stapes responses to 100 dB SPL pure tones, 1 mm cutting burr
and 2.3 mm cutting burr.

Figure 5: The frequency specific equivalent noise levels for 1 mm burrs. Each level was
obtained by averaging two equivalent noise levels at two separate trails. The first row of
the table indicates the frequency at which the equivalent noise level was calculated. The
second and the third rows indicate the level of the noise shown in the bar chart.

Figure 6: The frequency specific equivalent noise levels for 2.3 mm burrs. Each level
was obtained by averaging two equivalent noise levels at two separate trails. The first
row of the table indicates the frequency at which the equivalent noise level was
calculated. The second and the third rows indicate the level of the noise shown in the bar
chart.

Figures 7: Comparison of the frequency specific equivalent noise level for 2.3 mm
cutting bur and 3.1 mm diamond burr. Each level was obtained by averaging two
equivalent noise levels at two separate trails. The first row of the table indicates the

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Jiang et al. Drill and Noise
frequency at which the equivalent noise level was calculated. The second and the third
rows indicate the level of the noise shown in the bar chart.

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Jiang et al. Drill and Noise

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10 Hallmo P, Mair IWS. Drilling in Ear Surgery. A comparison of pre- and postoperative
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14 Needham AJ, Jiang D, Bibas AG, Fitzgerald O’ Connor A, Jeronimidis G. The effects
of Mass Loading the Ossicles with a Floating Mass Transducer on middle ear transfer
function. Otol Neurotol 2005; 26(2): 218-224.
15 Abel EW, Lord RM, Mills RP, Wang Z. Methodology for Laser Vibrometer studies of
stapes footplate displacement In: The function and Mechanics of Normal, Diseased and
Reconstructed Middle Ears, pp 89-97 ed Rosowski JJ, Merchant SN, 2000 Kerger
Publications, Hague, Netherlands.
16 Gjuric M, Schneider W, Buhr W, Wolf SR, Wigand ME, Experimental sensorineural
hearing loss following drill-induced ossicular chain injury Acta Otolaryngol 1997;
117(4): 497-500.

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17 Seki M, Miyasaka H, Edamatsu H, Watanabe K Changes in permeability of strial
vessels following vibration given to auditory ossicle by drill Ann Otol Rhinol Laryngol
2001; 110(2): 122-126
18 Pau HW, Leitner H, Hartwein J. Beruehrungen des trommelfells mit dem bohrer bei
ohroperationen: Moeglichkeit der innenohrschaedigung? Otorhinolaryngol Nova 1991;
1:297-300
19 Hallen O, Tjellstrom A. The use of the drill in ear surgery. Acta Otolaryngol 1975;
80(1-2):81-5.
20 Roberto M, Hamernik RP, Turrentine GA. Damage of the auditory system associated
with acute blast trauma. Ann Otol Rhino Laryngol Supp 1989; 140:23-34.
21 Schneider W, Gjuric M, Katalinic A, Buhr W, Wolf SR. The value of
methylprednisolone in the treatment of an experimental sensorineural hearing loss
following drill-induced ossicular chain injury: A randomized, blinded study in guinea-
pigs. Acta Otolaryngol 1998; 18(1): 52-55.
22 El-Hennawi DM, Badr El-Deen MH, Abou-Halawa AS, Nadeem HS, Ahmed MR.
Efficacy of intratympanic methylprednisolone acetate in treatment of drill induced
sensorineural hearing loss in guinea pigs. J Laryngol Otol 2005; 119: 2-7.
23 Scheibe F, Haupt H, Ising H, Preventive effect of magnesium supplement on noise-
induced hearing loss in the guinea pig Eur Arch Oto Rhino Laryngol 2000; 257(1): 10-
16.

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Figure

Figure 1 Jiang et al. Drill and Noise

LDV

ER-7C

ER-2

Temporal Bone and Holder

Recording Platform

Microscopic mounted
Polytec laser and sensor
Temporal Bone
Polytec HLV-1000
Vibrometer
Controller
ER-2 HLV-1000 and
ER-7C PC workstation

Figure 2 Jiang et al. Drill and Noise
Cutting
Diamond 1 mm
2.3 mm

1 mm
2.3 mm
3.1 mm

Jiang et al. Drill and Noise

Figure 3

P-P displacement (nm) 100.00

10.00 1000 10000
Frequency (Hz)
1.00

0.10

0.01
100

Jiang et al. Drill and Noise

Figure 4

P-P displacement (nm)10000
1000
100 1000 10000
10
1 Frequency (Hz)
0.1
0.01
100

2.3 mm cuting 1mm cutting 100 dB SPL tones

Jiang et al. Drill and Noise

Figure 5

1 mm burrs

130

dB SPL (eq) 120

110

100

90 0.5 124 8
96 93 97 102 99
Diamond 1 mm 101 96 102 103 108
Cutting 1 mm
Frequency (kHz)

Jiang et al. Drill and Noise

Figure 6

2.3 mm burrs

130

dB SPL (eq) 120

110

100

90 0.5 1 24 8
102 96 98 99 99
Diamond 2.3 mm 108 105 113 116 125
Cutting 2.3 mm
Frequency (kHz)