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Multi-frequency Tympanometry and Evidence-based Practice

Navid Shahnaz

School of Audiology & Speech Sciences

University of British Columbia

5804 Fairview Ave.

Vancouver, B.C. V6t 1Z3

Canada

Tel. 604-822-5953

Fax. 604-822-6569

E-mail: nshahnaz@audiospeech.ubc.ca

Published: Shahnaz, N. (September 2007). Multi-frequency Tympanometry and Evidence-based

Practice. American Speech-Language Pathology and Audiology (ASHA) Perspectives on Hearing

and Hearing Disorders: Research and Diagnosis. Volume 11, Number 1, 2-12.

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Tympanometry is a safe and quick method for assessing middle ear

function. Currently, tympanometry is typically conducted at a conventional probe tone

frequency of 226-Hz. Tympanometry performed using this frequency has proven valid in

identifying a variety of middle ear disorders (Lilly, 1984). However, standard 226 Hz

tympanometry often fails to distinguish normal middle ears from ears with pathologies

that affect the ossicular chain (Browning, Swan, & Gatehouse, 1985; Colletti, 1975,

1976; Lilly, 1984; Shahnaz & Polka, 1997). It can also fail to distinguish normal middle

ears from ears with pathologies in newborns and young infants below six months of age

(Balkany, Berman, & Simmons, 1978; Calandruccio, Fitzgerald, & Prieve, 2006; Holte,

Margolis, & Cavanaugh, 1991; Hunter & Margolis, 1992; Kei, Allison-Levick, Dockray,

Harrys, Kirkegard, Wong, Maurer , Hegarty, Young, & Tudehope, 2003; Marchant,

McMillan, Shurin, Johnson, Turczyk, Feinstein, & Murdell Panek, 1986; Margolis, Bass,

Ringdahl, Hanks, Holte, & Zapala, 2003; Paradise, Smith, & Bluestone, 1976) .

The main purpose of this perspective is to provide tangible evidence for why we

should include multi-frequency (MFT) and multi-component tympanometry testing in our

routine clinical practice for adults, children, and infant populations. In order to achieve

this goal, first some terms and basic principles underlying all immittance measurements

will be defined. Second, evidence with regard to outcome measurements for different

middle-ear pathologies using standard 226-Hz tympanometry and MFT will be reviewed.

Immittance Principles

Tympanometry is the measurement of the acoustic immittance of the ear as a

function of ear canal air pressure (ANSI, S3.39-1987). Immittance is a generic term that

encompasses impedance, admittance, and their components. Impedance (Z - in acoustic

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ohms) in the middle ear system is defined as the total opposition of this system to the

flow of the acoustic energy. Admittance (Y - in acoustic mmhos) is the reciprocal of

impedance and is the amount of acoustic energy that flows into the middle ear system.

Currently available immittance instruments typically measure admittance. There are two

important reasons for measuring admittance. First, the ear canal volume between the

probe tip and the tympanic membrane does not affect the shape of admittance

tympanograms and simply shifts the baseline; however, the shape of impedance

tympanograms is greatly affected by the ear canal volume (Shanks, 1984). Second, shape

of admittance tympanograms is more susceptible to changes in middle-ear condition

compared to impedance tympanograms; therefore, it lends itself to better classification of

tympanometric shapes (Fowler & Shanks, 2002)

There are three variables that determine admittance: stiffness, mass, and friction. The

first variable is the admittance offered by stiffness elements in the middle-ear system

which is called stiffness susceptance and is denoted by jBsa1 (also stiffness reactance, or -

-jXs in impedance terms). The second variable is the admittance offered by mass

elements in the middle ear system which is called mass susceptance and is denoted by -

jBma (also mass reactance or jXm in impedance terms). Total susceptance (or total

reactance in impedance terms) which store acoustic energy is the algebraic sum of the

jBma and jBsa elements as plotted along the Y-axis in Figure 1. If the total susceptance

(Ba) is positive, a system is stiffness controlled (between 0° to 90°as in Figure 1); if this

value is negative, the system is mass controlled (between 0° to -90° as in Figure 1). The

third variable, friction, determines the absorption or dissipation of acoustic energy. In

1 The subscript “s” denotes stiffness and the subscript “a” refers to the fact that the variable in question is

not compensated for the effect of ear canal volume (uncompensated).

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admittance terms, this element is called conductance and is denoted by Ga (also

resistance, or Ra in impedance system). Conductance is plotted on the X-axis and is the

only element that contributes to total admittance at resonant frequency (Figure 1).

The admittance of the system is a two dimensional quantity and is a vector sum of Ga

and the total susceptance (jBa) which is called rectangular notation (Figure 1). In polar

notation, admittance is expressed by its magnitude and the angle formed by the

admittance vector and the horizontal axis which is denoted by the phase angle, ϕ (Figure

1). To understand the application of multi-frequency, multicomponent tympanometry, it

is important to also consider how the relation between admittance components varies as a

function of frequency in the normal adult middle ear system. Figure 2 demonstrates the

variation of positively compensated2 admittance (Ytm), susceptance (Btm), and

conductance (Gtm) as a function of probe tone frequency. While acoustic resistance is

independent of frequency, acoustic conductance does vary with frequency. The variation

of Ga with frequency can be understood as a variation of Ra and Xa with frequency3.

Stiffness and mass susceptance are frequency dependent. Mass susceptance is directly

proportional to frequency and stiffness susceptance is inversely proportional to

frequency. Therefore, as frequency increases, the jBa progresses from positive values

(stiffness controlled) toward zero (resonance) to negative value (mass controlled).

Resonance of the middle ear system is achieved when the jBa is equal to 0 mmho (Figure

2).

2 Positive compensation refers to compensation for the effect of ear canal volume by subtracting the

positive tail of the tympanogram from the peak or minimum point (notch) in cases of multi-peaked B or G.

Ytm was derived from compensated rectangular component.

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At low frequencies (226 Hz & 450 Hz in this example) Btm is larger than Gtm and the

admittance vector lies between 45° and 90°. As frequency increases Btm decreases and

Gtm increases. Eventually Btm becomes equal to Gtm. This corresponds to a 45° phase

angle. With further increases in frequency, Gtm becomes larger than Btm, i.e., at phase

angles between 45° and 0°. At or near resonance (710 Hz in this example) Btm

approaches zero (Btm = 0; when stiffness and mass susceptance are equal) and, thus Gtm is

the only component contributing to the admittance of the system.

Multi-frequency, multi-component tympanometric parameters

Four potentially useful parameters that can be derived from MFT for diagnostic

purposes are 1) Tympanometric configuration - Vanhuyse Pattern, 2) Resonant frequency

(RF), 3) Frequency corresponding to admittance phase angle of 45 degree (F45°), and 4)

Static admittance (SA) at multiple frequencies. Vanhuyse, Creten, and Van Camp (1975)

examined tympanometric patterns in adults at various probe tone frequencies and

developed a model which predicts the shape of Ba and Ga tympanograms at 678 Hz in

normal ears and in various pathologies. Later, this model was extended to higher probe

tone frequencies (Margolis & Goycoolea, 1993). The Vanhuyse model categorizes the

tympanograms based on the number of peaks or extrema on the Ba and Ga tympanograms

and predicts four tympanometric patterns at 678 Hz. For example, the 1B1G pattern

(Table 1) has one peak on the Ba tympanogram and one peak on the Ga tympanogram;

3B3G has two peaks (maxima) and one trough (minima) on the Ba and the Ga

tympanograms (Table 1). It has been shown that the transition between different

Vanhuyse patterns can be shifted to higher or lower probe tone frequencies depending on

the nature of middle-ear pathology (Shahnaz, 2000).

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RF is the frequency at which the total susceptance is zero. The resonant frequency

of the middle ear system may be shifted higher or lower compared to healthy ears by

various pathologies. RF is directly proportional to the square root of stiffness and

indirectly proportional to the square root of mass; e.g., otosclerosis increases the stiffness

of the middle-ear system; therefore, shifting the RF of the middle ear system to higher

probe tone frequencies (Shahnaz & Polka, 1997). RF can be measured either by plotting

the susceptance tympanogram at various probe tone frequencies (e.g, using Virtual 310 or

GSI-33 or Tympstar) or by plotting peak compensated B (Bpeak – Btail), also called delta B

(∆B), as a function of probe tone frequency (e.g., using GSI-33 or Tympstar). Figure 3

shows a plot of B and G tympanogram as a function of air pressure obtained from Virtual

310 middle-ear analyzer. Whenever the notch value on the susceptance tympanogram

becomes equal to a positive tail (positive compensation) or negative tail (negative

compensation) the total susceptance is zero and the system is at resonant frequency (see

Figure 3). Figure 4 shows a plot of delta B and G as a function of probe tone frequency

obtained using GSI-Tympstar. When delta B approaches zero line (0 mmho) the system is

at resonance. Table 2 shows the mean estimates of the middle-ear RF obtained using

sweep frequency (SF) recording for both positive and negative compensation of the ear

canal volume using two commercially available middle-ear analyzers.

F45° is a frequency at which compensated susceptance becomes equal to the

conductance tympanogram (see Figure 2 and 4). This parameter may also be shifted

higher or lower by various middle ear pathologies similar to the middle-ear RF. Table 3

shows the mean estimates of F45°obtained using SF recording for both positive and

negative compensation of the ear canal volume using the Virtual 310 middle ear analyzer.

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Shahnaz and Davies (2006) reported that the Chinese adults had significantly higher F45º

and RF than the Caucasian adults (Table 2 and Table 3). They also reported that

applying the Caucasian norms to a group of mainly Caucasian adults with surgically

confirmed otosclerosis, resulted in improved overall test performance when compared to

the combined Caucasian and Chinese norms and the Chinese only norms.

Standard versus high frequency tympanometry in adults

Standard tympanometry has often failed to distinguish normal middle ears from

ears with lesions that specifically affect the ossicular chain, such as otosclerosis

(Browning, Swan, and Gatehouse, 1985; Colletti, 1975, 1976; Lilly, 1984; Shahnaz and

Polka, 1997; Shahnaz & Polka, 2002; Zhao, Wada , Koike, Ohyama, Kawase, &

Stephens, 2002). One major effect of otosclerosis is to increase the stiffness of the

middle ear system resulting in a shift of the middle ear RF to the higher values. The

greatest impact of middle ear pathology is at probe tone frequencies close to the RF

(Margolis & Shanks, 1991; Liden, Harford, & Hallen, 1974; Shanks, 1984) or admittance

phase angle of 45 degrees (Shahnaz & Polka, 1997).

Test performance analysis applied by Shahnaz and Polka (1997) provides several

indices (sensitivity or hit rate, specificity or false alarm, and A') that can be compared

across different tympanometric measures. However, one limitation of this analysis is that

it can only compare measures with respect to a single decision criterion or cut off value.

Standard statistical criteria, e.g., 95% confidence interval, are typically used to define

such cut off values. However, these cut off values are not necessarily the best decision

thresholds to use to distinguish otosclerotic ears from healthy ears for a given measure.

Moreover, comparing the test performance among different tympanometric measures

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based only on a single cut off value can be misleading because it does not take into

account all possible decision criteria. In order to overcome these limitations, Receiver

Operating Characteristic (ROC) curve analysis can be used (see Shahnaz and Polka, 2002

for more details). The ROC plots for static admittance measures conducted using 226-

Hz, 630-Hz, and 710-Hz probe tone frequencies are shown in Figure 6 (from Shahnaz &

Polka, 2002). The results indicate that static admittance obtained at 630 and 710 Hz are

better than 226-Hz in distinguishing normal from otosclerotic ears. Figure 7a and 7b

compares the ROC curve of RF and F45° in 52 surgically confirmed otosclerotic ears

(Shahnaz, Bork, & Polka, in progress) and 76 normal Caucasian adults (Shahnaz and

Davies, 2006) to standard 226 Hz static admittance (Ytm) in distinguishing normal from

otosclerotic ears. As can be seen, both RF and F45 have significantly better outcome in

distinguishing otosclerotic ears from normal ears. Zhao et al. (2002) also compared the

result of conventional 226-Hz tympanometry to MFT in 36 ears with surgically

confirmed otosclerosis. They reported that significantly higher percentage of otosclerotic

ears was detected by MFT than conventional 226-Hz tympanometry.

While similar ROC data is not available for ossicular discontinuity, Funasaka and

Kumakawa (1988) reported that there was very little overlap in RF between otosclerotic

ears and ossicular discontinuity. Wada, Koike, and Kobayashi (1998) also reported that

the mean resonant frequency between 12 cases of surgically confirmed ossicular fixation

and 26 cases of ossicular discontinuity was statistically different. The authors also

compared the clinical value of multifrequency tympanometry with a standard 220 Hz

tympanogram. The rate of correct diagnosis for the fixation group using resonant

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frequency was 74%, whereas, this rate was 53% using Type As classification system at

low probe tone frequency.

Standard versus high frequency tympanometry in children

Next to the common cold, infection of the middle-ear (otitis media-OM) is the

most common childhood disease. If left untreated, OM may result in permanent hearing

loss or other medical complications that may cause damage to the structures of the

middle-ear (Berman, 1995; Roark & Berman, 1996). The cost associated with OM has

been estimated to be around five billion dollars a year in the United States (Hendley,

2002). Otitis media with effusion (OME) is one of the most prevalent illnesses among

children in Canada and United States and probably among children all over the world

(Friel-Patti et al., 1982; Hubbar et al., 1985; Northern and Downs, 2002). The frequency

of OM and its huge economic burden, estimated to be around five billion dollars a year in

the United States alone (Hendley, 2002), have motivated researchers to seek out the most

efficient clinical strategies for early diagnosis and management of this condition.

Nozza, Bluestone, Kardatzke, & Bachman, (1992, 1994) determined sensitivity,

specificity, and positive predictive value of different tympanometric parameters at

conventional 226-Hz probe tone frequency in a group of children prior to myringotomy.

They reported that out of all quantifiable parameters obtained from conventional 226-Hz

tympanograms, tympanometric width (TW), or the sharpness of the tympanometric peak,

was the best single criterion for detection of middle ear effusion (sensitivity: 81%,

specificity: 82%). Margolis, Schachern, and Fulton (1998) created specific middle ear

lesions in chinchillas and compared the results of conventional 226-Hz tympanometry

and MFT. They reported that static admittance had a sensitivity of 73% and a specificity

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of 75% for detecting significant middle ear pathology while TW was not an effective

diagnostic test. Combinations of MFT parameters such as low RF or irregular patterns

had a sensitivity and specificity of 91% and 100%, respectively. They concluded that

MFT detects some middle ear pathologies that are not detected by conventional 226-Hz

tympanometry. Moreover, it has been shown that conventional 226-Hz tympanometry is

unable to detect sequelae and subtle changes in middle-ear mechanics following OM;

however, MFT appears to be sensitive to these changes (Hanks & Robinette, 1993;

Margolis, Hunter, & Giebnik, 1994; Vlachou, Ferekidis, Tsakanikos, Apostolopoulos,

and Adamopoulos, 1999; Vlachou, Tsakanikos, Douniadakis, and Adamopoulos, 2001).

More recently, Harris, Hutchinson, and Moravec (2005) evaluated the effectiveness of

conventional 226-Hz and MFT tympanograms in detecting middle ear effusion in 21

children prior to myringotomy. They reported that all abnormal cases identified by

conventional 226-Hz tympanometry were also identified by MFT; however, 3 abnormal

cases that were identified as normal by 226-Hz tympanometry, were correctly identified

as abnormal by MFT.

Standard versus high frequency tympanometry in infants

Standard low-frequency tympanometry (220 or 226-Hz) was first conducted with

infants under six months of age as early as 1973 (Keith, 1973). However, tympanometric

patterns observed in newborn infants do not conform to the classic patterns found in older

infants, children, and adults. For example, with respect to tympanometric shape infants

younger than six months of age with surgically confirmed OME, often present with low-

frequency tympanograms that appear normal and bell-shaped with a single or notched

peak (Hirsch, Margolis & Rykken, 1992; Margolis, Ringdahl, Hanks, Holte, & Zapala,

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2003; Marchant et al. 1986; Paradise, Smith, & Bluestone, 1976; Rhodes, Margolis,

Hirsch, & Napp, 1999). Neither of theses patterns is typical of a child or adult ear with

OME. The unusual characteristics of neonate tympanograms have been attributed to the

physiological differences between neonate and adult ears (Himelfarb, Popelka, &

Shanon, 1979; Margolis & Hunter, 2000; Sprague, Wiley, & Goldstein, 1985). In

newborns, the non-rigid ear-canal may contribute to the irregular shape of tympanograms

at low frequencies (Keefe, Bulen, &Arehart, 1993). The ear-canal diameter in infants and

young children can be changed up to 70% in response to the pressure changes

implemented in tympanometry (Holte, Cavanaugh, & Margolis, 1990). Nevertheless,

Holte et al. (1990) have shown that greater mobility of the newborn ear-canal is not

solely responsible for the irregular tympanometric shape observed in young babies.

Rather, Holte and colleagues showed that the highly distensible ear canal of the neonate

has the greatest effect on the tails of the tympanograms that are used to estimate ear canal

volume.

The external auditory canal and middle-ear undergo structural changes over the

first two years after birth which can affect the physical properties of sound transmission

to the cochlea. Some of these physical changes include: (a) an increase in size of the

external ear (Anson & Donaldson, 1981), middle-ear cavity and mastoid (Eby & Nadil,

1986; Ikui, Sando, Haginomori, & Sudo, 2000), (b) a change in the orientation of the ear

drum (Eby & Nadil, 1986), (c) a decrease in the overall mass of the middle-ear due to

changes in bone density (Anson & Donaldson, 1981), or to loss of amniotic fluid in the

middle-ear (Paparella, Shea, Meyerhoff, & Goycoolea, 1980), (d) tightening of the joints

of the middle-ear bones (Anson & Donaldson, 1981), and (e) fusing of the tympanic ring

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and formation of the bony ear-canal wall (Saunders, Doan, & Cohen, 1993). The

presence of residual amniotic fluid and mesenchyme in the ear canal and middle ear of

newborns may also be relevant in understanding the physics of the newborn ear given

that small amounts of fluid or debris against the eardrum (in the middle or outer ear)

increase both mass and resistance in children and adult ears. However, this argument is

weakened by the finding that neonatal chinchillas with clean middle ears have the same

kind of chaotic impedance characteristics as human infants (Hsu, Margolis, & Schachern,

2000; Hsu, Margolis, & Schachern, Javel, 2001). Although the precise factors involved

are not clear, on the basis of tympanometric data the newborns’ middle-ear impedance

characteristics appear to be dominated by the effect of mass/resistive elements at low

probe-tone frequencies (Holte et al, 1991). This contrasts with the middle-ear impedance

characteristics in young children and adults which are dominated by the effect of stiffness

elements at low probe-tone frequencies (Shahnaz & Polka, 1997). Therefore, the

tympanometric characteristics of neonates are sufficiently different from adults to deserve

a unique definition of normal.

Several studies indicate that the most informative tympanometric recordings in

neonates are derived using higher probe-tone frequencies (Calandruccio, Fitzgerald, &

Prieve, 2006; Hirsch et al., 1992; Hunter & Margolis, 1992; Kei, Allison-Levick,

Dockray, Harrys, Kirkegard, Wong, Maurer , Hegarty, Young, & Tudehope, 2003;

Marchant et al., 1986; Rhodes, Margolis, Hirsch, & Napp, 1999).

Gliddon and Sutton (2001) assessed one hundred NICU and 100 well babies at

birth and at 8 months of age using 220-Hz and 660-Hz tympanometry and acoustic

reflexes. Admittance tympanograms were recorded using a Grason-Stadler GSI-33

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(Version 2). Tympanograms were defined as abnormal if they were 1) flat, 2) had static

admittance (derived with positive-tail compensation) below 0 mmho or 3) had static

admittance above 0 mmho with negative middle-ear pressure of less than 100 daPa.

Using these criteria, they found that, among NICU babies, an abnormal 660 Hz

tympanogram at birth is one of the best predictors of OME at eight months of age. Kei et

al. (2003) reported data on 226-Hz and 1000-Hz admittance tympanograms in 122

healthy neonates (1-6 days) with normal TEOAE results using a Madsen Capella

OAE/middle ear analyser. In infants who passed the TEOAE screen they found three

different types of admittance tympanograms at 1000-Hz probe tone frequency. Type 1,

the single-peaked tympanogram, was the most commonly occurring (92.2%)

tympanogram at this frequency. Type 2, a flat tympanogram, was observed in 5.7% of

the infants and Type 3, double-peaked tympanogram, was observed in 1.2% of the

infants. A notched 226-Hz tympanogram was recorded for 47.5 % of these infants.

They concluded that the Type 1(single peaked) tympanogram is probably indicative of

normal middle ear function. They also noted that the few infants with Type 2

tympanograms who passed TEOAE screen exhibited a less robust TEOAE which could

be indicative of compromised middle-ear condition. Margolis et al. (2003) reported

normative data for 1-kHz admittance tympanograms in sixty-five NICU graduates tested

at a mean age of 3.7 weeks (GA: 37 weeks) and in thirty full-term infants tested at 2-4

weeks who passed an otoacoustic emissions (OAE) screen. This study set the pass-fail

criterion at the 5th percentile (95% passed). These norms were then applied to 1-kHz

tympanograms from two groups of full-term babies and one group of NICU graduates.

The negative-tail compensated static admittance was selected for the pass-fail criterion

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because of larger mean value on the negative tail side than the positive tail side. Nearly

all of the infants who passed the OAE screening had a single-peaked tympanogram at 1-

kHz and 91% also presented with passing static admittance measures. Moreover, infants

who passed the OAE screening had significantly higher 1-kHz static admittance than

those who failed, suggesting a strong relationship between middle-ear transmission

characteristics and OAE responses.

Calandruccio et al. (2006) measured multi-frequency and multi-component

tympanometry in 33 infants at multiple times between the ages of four weeks and two

years using the Virtual-310 middle-ear analyzer. They found that the typical Vanhuyse

patterns observed in their younger infants and adults differed, especially at 1-kHz probe

tone frequency. Specifically, for the 1-kHz tympanograms, most adults (80%) had a

3B1G pattern whereas infants and toddlers were equally likely to show either a 1B1G or

a 3B1G pattern. These differences in Vanhuyse pattern suggest that the newborn middle

ear behaves like a mass-dominated system at low probe frequencies and a stiffness-

controlled system at high probe frequencies, which is the opposite of what is observed in

the adult ear. In general, in both well babies and NICU babies, 226-Hz tympanograms are

typically multi-peaked in ears that passed or referred on transient otoacoustic emission

(TEOAE), limiting the specificity and sensitivity of this measure for differentiating

normal and abnormal middle-ear conditions. Tympanograms obtained at 1-kHz are

potentially more sensitive and specific to presumably abnormal and normal middle-ear

conditions. Tympanometry at 1-kHz is also a good predictor of presence or absence of

TEOAE. Table 3 shows normative tympanometric values from 1 kHz tympanograms for

neonatal intensive care unit (NICU) babies and full term babies.

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Conclusion

In summary, all middle-ear pathologies that are identified as abnormal by

conventional 226-Hz tympanometry can also be identified by MFT; however,

conventional tympanometry may fail to distinguish middle-ear pathologies that are

correctly identified as abnormal by MFT. Moreover, MFT is capable of distinguishing

subtle mechano-acoustical changes in the middle-ear system following middle ear disease

which may not be distinguished by conventional tympanometry. This may prove useful in

identifying at-risk middle ear systems or identifying persistence of the middle-ear

pathology. It should be noted that conventional 226-Hz tympanometry may still be a

preferred method for estimating equivalent ear canal volume which has application in

assessment of integrity of the tympanic membrane, and functionality of pressure

equalization (PE) tube. It is highly recommended to combine conventional 226-Hz

tympanometry with MFT in assessment of newborns, children, and adults.

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21

Figure 1: The admittance terminology [Bm: mass susceptance; Bs: stiffness susceptance;

Ba: total susceptance is algebraic sum of Bm and Bs; |Y|: absolute admittance magnitude;

ϕ: admittance phase angle]. “j” is a symbol for an imaginary number and it is equal to

1- in complex number notation and indicates that conductance and susceptance cannot

be combined by simple addition because they are vectors that operate in different

directions.

jBa

jBstifnes

-jBmass Ga

Ya

ϕϕϕϕ

90°°°°

0°°°°

Polar Notation

|Y|= 2.1 mmho

ϕ = 45°

Rectangular Notation

Ya = Ga + jBa =

Ga + j(Bma + Bsa)

-90°°°°

Resonance

22

Figure 2: Peak compensated static admittance (Ytm= ), susceptance (Btm), and

conductance (Gtm) as a function of probe tone frequency from 226 Hz through 1120 Hz.

Points corresponding to admittance phase angle of 45° and 0° (resonant frequency) are

also shown. Two corresponding tympanometric patterns that is most likely to be observed

at corresponding probe tone frequencies are also shown.

23

Figure 3: Illustration of the method used to estimate the resonant frequency from the

positive tail of the susceptance (B) tympanogram from a sweep pressure recording using

Virtual 310 middle-ear analyzer. In this example the frequency (900 Hz ) at which notch

on the B tympanogram first became equal or less than a positive tail was.considered as

resonant frequency.

Right 900 Hz Tympanogram

-500 -400 -300 -200 -100 0 100 200 300 400 500

Air Pressure (daPa)

6.00

5.00

4.00

3.00

2.00

1.00

0.0

Ga:

Ba:

Ga:

Ba:

Positive

Tail

24

-14

-12

-10

-8

-6

-4

-2

0

2

4

6

250 450 650 850 1050 1250 1450 1650 1850

Frequency-Hz

immittance - mmho

Delta B Delta G

∆Β = 0 mmho

ϕ = 0°

∆Β = ∆G

ϕ = 45°

Figure 4: GSI-Tympstar recording of B and G (in mmho) at +250 daPa and at peak

pressure while the probe tone frequency was swept from 220 to 2000 Hz in 50 Hz

intervals (sweep frequency recording). The difference between B/G at +250 daPa and

peak pressure (referred to as ∆B/G) was computed at each probe tone frequency. This

∆B/G is essentially a compensated B and G measure. The ∆B and ∆G was then plotted as

a function of frequency (in Hz). The frequency at which ∆B is closest to 0 dB

corresponds to the resonant frequency of the middle ear system. The frequency at which

∆B is closest to ∆G corresponds to admittance phase angle of 45°.

25

Figure 5: Illustration of the method used to estimate the admittance phase angle of 45°.

In this example the frequency at which conductance (G) first became larger than

susceptance (B) was 710 Hz.

Right 710 Hz Tympanogram

-500 -400 -300 -200 -100 0 100 200 300 400 500

Air Pressure (daPa)

6.00

5.00

4.00

3.00

2.00

1.00

0.0

G

B

Admittance - mmho

26

False Positive

1.00.75.50.250.00

Sensitivity

1.00

.75

.50

.25

0.00

Reference Line

Y+ @ 710 Hz

Y+ @ 630 Hz

Y+ @ 226 Hz

Figure 6: Receiver Operating Characteristic (ROC) curve analysis for positively

compensated static admittance, Y+ at three different probe tone frequencies.

27

226 Ytm +

RF +

0 20 40 60 80 100

Faslse Alarm

100

80

60

40

20

0

Sensitivity

226Ytm+

F45 +

0 20 40 60 80 100

False Alarm

100

80

60

40

20

0

Sensitivity

Figure 7a-b: Receiver Operating Characteristic (ROC) curve analysis for positively

compensated resonant frequency, RF+ (a) and positively compensated admittance phase

angle of 45°, F45° + (b) compared with positively compensated static admittance at

conventional 226 Hz (226Ytm+).

a

b

28

Vanhuyse et

al. (1975)

model

Corresponding

Phase Angle

Susceptance (B) and Conductance (G)

Tympanograms at 678-Hz

1B1G

45°-90°

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

-300 -200 -100 0 100 200 300

B

G

3B1G 0°-45°

0.00

1.00

2.00

3.00

4.00

5.00

6.00

-300 -200 -100 0 100 200 300

G

B

3B3G 0°-45°

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

-300 -200 -100 0 100 200 300

B

G

5B3G -45°- -90°

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

-300 -200 -100 0 100 200 300

G

B

Table 1: Normal Vanhuyse patterns at 678-Hz probe tone frequency. The number of

conductance peaks must not exceed three, and the number of susceptance peaks must not

exceed five. The distance between the outermost conductance maxima must not exceed

the distance between the 5B3G susceptance maxima. The distance between the outermost

maxima must not exceed 75 daPa for 3B3G tympanograms shapes and 100 daPa for

5B3G tympanogram shapes.

29

Table 2: Descriptive statistics for resonant frequency (RF), measured by sweep

frequency (SF) with both positive (+) and negative (-) compensation from several

published data. Shanks et al. (1993) reported median values (*); unreported values

denoted by --; M = male; F = female; C = combined genders.

SF

+ compensation - compensation

Investigator Mean

(Hz)

SD

(Hz)

90%

Range

Mean

(Hz)

SD

(Hz)

90%

Range

M 957 230 630-1400 1220 280 800-1800

F 962 162 710-1250 1189 270 800-1800

Shahnaz & Davies

(2006)

Chinese (N=76)

(age = 18-33 yr)

Virtual 310

C 962 190 666-1250 1201 273 800-1800

M 896 191 574-1250 1033 249 710-1560

F 890 138 630-1120 1004 192 630-1400

Shahnaz & Davies

(2006)

Caucasian (N=83)

(age = 18-33 yr)

Virtual 310

C 892 164 630-1120 1015 219 710-1400

Margolis & Goycoolea

(1993) N=56

Virtual 310 (age = 19-48 yr)

1135 306 800-2000 1315 377 710-2000

Shanks et al. (1993) N=26

Virtual 310 (age = 20-40 yr)

817* -- 565-1130 1100 * -- 678-1243

Holte (1996) N=144

Virtual 310 (age = 20-90 yr)

905 184 630-1250 1001 257 710-1400

Hanks & Mortenson

(1997) N=53

GSI-33 (age = 18-25 yr)

908 188 650-1300 1318 308 900-1750

M 826 146 -- 993 259 --

F 898 189 -- 1076 297 --

Wiley et al. (1999)

Virtual 310 N=404

(age = 48-90 yr) C 866 175 -- 1039 283 --

Valvik et al. (1993)

N=100

GSI-33

1049 261 650-1500

30

Table 3: Descriptive statistics for the frequency corresponding to an admittance phase

angle of 45° (F45°) measured by sweep frequency (SF) for both positive (+) and negative

(-) compensation. Shanks et al. (1993) reported median values (*); Unreported values are

denoted by --; M = male; F= female; C = combined genders.

SF

+ compensation - compensation

Investigator Mean

(Hz)

SD

(Hz)

90%

Range

(Hz)

Mean

(Hz)

SD

(Hz)

90%

Range

(Hz)

M 554 140 269-800 767 156 521-1000

F 572 127 370-800 756 155 560-1120

Current Study

(Chinese)

C 566 131 355-800 759 155 560-1006

M 521 129 317-795 661 167 452-1000

F 550 114 384-800 649 150 450-900

Current Study

(Caucasian)

C 537 121 355-800 655 157 450-935

Shanks et al. (1993) 817* -- 565-1130 1100 * -- 678-1243

Shahnaz (2000) 955 206 612-1347 1124 309 710-1600

31

Table 4: Mean, standard deviation (SD), and 90% range (5th - 95th percentile) for static

admittance (SA) obtained from Ya at 1-kHz probe-tone frequency for NICU babies and

well babies. Please note that in Calandruccio et al. (2006) study SA was computed from

rectangular components and Median is reported.

N Y @ + 200 daPa Y @ - 400 daPa + 200Ya daPa - 400Ya daPa

Mean SD 90% range

Mean SD 90% range

Mean SD 90% range

Mean SD 90% range

NICU Shahnaz, Miranda, & Polka, 2007 32 weeks CGA GSI-Tympstar

54 ears

1.24 0.25 0.87-1.70

0.64 0.23 0.39-1.15

0.77 0.52 0.10-1.50

1.38 0.61 0.53-2.31

NICU Margolis et al., 2003 32.8 GA GSI-33

105 ears

1.40 0.30 0.90-1.90

0.60 0.20 0.40-1.00

0.80 0.5 0.20-1.60

1.50 0.70 0.60-2.70

Well-babies Margolis et 2-4 weeks GSI-33

46 ears

1.40 0.40 0.8-2.2

0.80 0.40 0.3-1.40

1.30 1.0 0.10-3.50

1.90 1.30 0.60-4.30

Well-babies Calandruccio et al. 2006 4-10 weeks Virtual 310

39 ears

1.26 --- 0.99-1.71

--- --- --- 1.06 ---- 0.20-2.25

--- --- ---