Electrocochleography: A Review of RecordingApproaches, Clinical Applications, and New Findingsin Adults and ChildrenDOI: 10.3766/jaaa.21.3.2

John A. Ferraro*

Abstract

Research related to expanding and improving the clinical use of electrocochleography (ECochG) hasbeen ongoing for 25 yr at the University of Kansas Medical Center. This article presents highlights of

findings from our laboratory during this period that have contributed to current ECochG recordingapproaches and clinical applications. A review of new data related to improving the sensitivity of ECochG

in the diagnosis of Meniere’s disease, the use of an ear canal recording approach for improving auditorybrain stem response testing in newborns, and technical aspects related to recording the cochlear micro-

phonic in newborns also will be presented.

Key Words: Action potential, auditory brain stem response, auditory evoked potential, auditoryneuropathy, cochlear microphonic, condensation, electrocochleography, endolymphatic hydrops,

extratympanic, Meniere’s disease, rarefaction, summating potential, transtympanic, tympanicmembrane

Abbreviations: ABR 5 auditory brain stem response; AEP 5 auditory evoked potential; AN 5 auditory

neuropathy; AP 5 action potential; C 5 condensation; CM 5 cochlear microphonic; ECochG 5

electrocochleography; ELH 5 endolymphatic hydrops; ET 5 extratympanic; MD 5 Meniere’s

disease; R 5 rarefaction; SP 5 summating potential; TM 5 tympanic membrane; TT 5 transtympanic

Theability to record the receptor potentials of the

cochlea and the whole nerve/compound auditory

nerve action potential (AP) in humans via elec-

trocochleography (ECochG) has led to numerous inves-

tigations in the Hearing and Speech Department’sauditory evoked potential laboratory at the University

of Kansas Medical Center (KUMC) during the past

25 yr. Some of this research has been done in collabora-

tion with colleagues from other universities, most nota-

bly John Durrant (University of Pittsburgh) and Roger

Ruth (University of Virginia). In general these studies

have been designed to improve the techniques and ap-

proaches for recording ECochG noninvasively andpainlessly; identifying, modifying, and expanding its

clinical applications; and seeking ways to improve both

the sensitivity and the specificity of these measure-

ments in the diagnosis, assessment, and management

of inner ear and auditory nerve disorders.

Although it has been available to the hearing scien-

tist since the 1930s, ECochG’s emergence as a clinical

tool was due in part to the discovery and applicationof the auditory brain stem response (ABR) over 40 yr

later. Utilization of improved signal-averaging ap-

proaches for recording the miniscule and extremely

early responses of auditory centers in the brain stem

helped to direct attention back to the periphery.

Another important factor that has facilitated the clini-cal popularity of ECochG, at least in the United States,

is the development and refinement of noninvasive re-

cording techniques. Ruben and his coworkers (1960),

for example, measured the AP intraoperatively from

patients undergoing middle ear surgery. A few years

later, nonsurgical techniques that involved passing a

needle electrode through the tympanic membrane

(TM) to rest on the cochlear promontory were intro-duced (e.g., Yoshie et al, 1967; Aran and LeBert,

1968). This transtympanic (TT) recording approach to

ECochG is still used in Europe and other countries out-

side the United States. Extratympanic (ET) alterna-

tives to TT recording methods began to appear in the

early to mid-1970s. Cullen and colleagues (1972) per-

formed recordings from the lateral surface of the TM,

while Coats (1974) used a silver ball electrode gluedto a small plastic leaf to achieve recordings from the

*Hearing andSpeechDepartment, IntercampusProgram inCommunicative Disorders, andSchool of AlliedHealth,University of KansasMedical Center

John A. Ferraro, Ph.D., Information Hearing and Speech Department, University of Kansas Medical Center, 39th and Rainbow Blvd., Kansas City,KS 66160-7605; Phone: (913) 588-5937; E-mail: jferraro@kumc.edu

J Am Acad Audiol 21:145–152 (2010)

145

ear canal. My initial research utilizing ECochG was

based on ear canal measurements made with the Coats

Mylar leaf electrode (Ferraro et al, 1983; Ferraro et al,

1985). In subsequent studies we employed a gold foilelectrode wrapped around a compressible foam earplug

(i.e., the TIPtrodeTM), which tended to produce less dis-

comfort for subjects than the leaf electrode (e.g., Ruth,

Lambert, et al, 1988). Since around 1990, however, vir-

tually all of our adult studies have utilized a modified

version of the electrode described by Stypulkowski

and Staller (1987), which directed and facilitated atten-

tion back to the TM as the primary site of choice forECochG recordings. Figure 1 is an illustration of the

“tymptrode” we currently use for our recordings.

The purpose of this article is to provide a review of

recent research in our clinic/laboratory at the KUMC

related to the recording methods and clinical applica-

tions of ECochG. These studies include a 5yr retrospec-

tive review of our patient database to evaluate the

sensitivity and specificity of the recording protocol weuse when ECochG is administered to help identify/rule

out Meniere’s disease/endolymphatic hydrops. Other

research utilizing an ECochG approach to record the

ABR and cochlear microphonic (CM) in newborns also

will be described. For amore complete review of current

ECochG procedures and applications that includes a

discussion of electrode and patient preparation, re-

cording parameters, waveform interpretation, and nor-mative values, the reader is referred to Ferraro and

Durrant (2006) and Ferraro (2007).

ECochG RECORDING METHOD

Asindicated above, there are two, general recording

approaches for ECochG: TT and ET. The TT

method involves penetrating the TMwith a needle elec-

trode so that the tip rests on the cochlear promontory.

ET approaches utilize primary recording sites that are

peripheral to the tympanic cavity (thus the name“extratympanic”). The skin of the ear canal and the

external surface of the TM have evolved to be the most

popular recording sites. I use the term TM ECochG for

the latter approach (Ferraro and Ferguson, 1989) even

though this procedure is still considered to be an ET

one. As my colleagues and I have reported numeroustimes (e.g., Ferraro, 2000; Ferraro and Durrant,

2002, 2006), both TT and ET approaches to ECochG

have advantages and disadvantages. An advantage of

the TT approach is the proximity of the primary record-

ing electrode to the response generators, which produ-

ces large components with relatively little signal

averaging. ET recordings require more signal averag-

ing and are smaller in magnitude but do not requirethe assistance of a physician to place the electrode or

a topical (usually) anesthetic to dull the pain of punctur-

ing the TM. In 1994, my colleagues and I compared TT

and ET (TM) recordings from the same patients. Figure

2 illustrates our findings from this study (Ferraro et al,

1994). The ECochG tracings in the top panel were

recorded from the cochlear promontory of a patient with

suspectedMeniere’s disease (MD), while the lower trac-ings were measured from the TM. Although the magni-

tude of the TT recordings is approximately four times

larger than the TM responses, both sets of waveforms

display an enlarged summating potential (SP)/AP

amplitude ratio, which was the primary diagnostic cri-

terion we used for reporting a positive finding for MD.

In other words, the features of the waveform that were

essential to interpreting the electrocochleogram were

Figure 1. Illustration of the “tymptrode” used for recording elec-trocochleography from the tympanic membrane (from Ferraro,2007, p. 401).

Figure 2. Abnormal electrocochleograph responses to clicksrecorded from the promontory (transtympanic [TT]) and tympanicmembrane (TM) of the affected ear of a patient withMeniere’s dis-ease. Although the magnitudes of the TT responses are approxi-mately 43 greater than the extratympanic recordings, both setsof tracings display an enlarged summating potential (SP)/actionpotential (AP) amplitude ratio, which is a positive finding forMeniere’s disease. “Base” indicates the reference point for SPandAP amplitudemeasurements. The amplitude scale is inmicro-volts; the time scale is in milliseconds. Stimulus onset was delayedby 2msec (from Ferraro et al, 1994, p. 27).

Journal of the American Academy of Audiology/Volume 21, Number 3, 2010

146

apparent in both TT and TM recordings. Furthermore,

Stypulkowski and Staller (1987) and Ferguson and I

(Ferraro and Ferguson, 1989) showed that ECochG

components recorded from the TM displayed magni-tudes that were at least twice as large as corresponding

measurements made from the ear canal. Thus, the TM

offers a good and practical compromise between ear

canal and TT recording sites, producing components

with larger magnitudes than corresponding ET mea-

surements while eliminating the discomfort and

medical-related requirements associated with TT ap-

proaches and, most importantly, preserving the fea-tures of the waveform essential to the diagnosis of MD.

It also should be noted that the technique of placing

the tymptrode is partially “blind” since the TM is

obscured by the electrode tip during this process. Proper

placement is verified by having the subject acknowledge

when he or she feels it touching the membrane and

monitoring of the electrical noise floor as the electrode

is inserted into the ear canal. The noise floor drops dra-matically and becomes free of cyclic artifact and clipped

peaks when the tip makes proper contact with the TM.

In addition, although TM recordings can be made using

circumaural headphones, tubal earphones by compari-

son offer at least two important advantages: (1) the

speaker diaphragm is farther away from the ear, which

helps to reduce electromagnetic artifact in the record-

ing, and (2) the compressible foam tip of the sound tubehelps to stabilize and hold the tymptrode in place.

ECochG IN THE DIAGNOSIS OF MENIERE’S

DISEASE/ENDOLYMPHATIC HYDROPS

As shown in Figure 2, and documented in the liter-

ature for over 30 yr, ECochG responses recordedfrom patients with MD/endolymphatic hydrops (ELH)

often are characterized by an enlarged SP and SP/AP

amplitude ratio (e.g., Schmidt et al, 1974; Eggermont,

1976; Gibson et al, 1977; Morrison et al, 1980; Coats,

1981, 1986; Kitahara et al, 1981; Goin et al, 1982;

Kumagami et al, 1982; Ferraro et al, 1983; Ferraro

et al, 1985; Staller, 1986; Dauman et al, 1988; Ruth,

Lambert, et al, 1988; Ruth, 1990; Ferraro andKrishnan, 1997). One rationale that has been offered

(but not verified) for this finding is that an increase

in endolymph volume creates mechanical biasing of

vibration of the organ of Corti that amplifies the SP

since at least some of its components represent non-

linearities in the transduction process. Whether the na-

ture of this increased distortion is mechanical (Gibson

et al, 1977) and/or electrical (Durrant and Dallos, 1972;Durrant and Gans, 1975) has not been resolved, and

other factors such as biochemical and/or vascular

changes may also be responsible (Eggermont, 1976;

Goin et al, 1982; Staller, 1986). Despite verification of

its bases, an enlarged SP/AP amplitude ratio has evolved

as the primary characteristic of an electrocochleogram

that is positive for MD.

While the specificity of the SP/AP amplitude ratio inthe diagnosis MD has been reported to be 90% or higher

(Ferraro et al, 1983; Pou et al, 1996;Murphy et al, 1997),

the sensitivity of this measurement in the general

Meniere’s population is only between 55 and 65% or less

(Gibson et al, 1977; Coats, 1981; Kitahara et al, 1981;

Kumagami et al, 1982; Campbell et al, 1992; Margolis

et al, 1995; Pou et al, 1996; Ferraro and Tibbils, 1999).

In other words, patients who display enlarged SP/APamplituderatiosarevery likely toreceiveapositivediag-

nosis forMD,butonlyaroundhalf of the individualswith

MD have enlarged ratios. Fluctuations in symptoms,

deterioration of outer hair cells inmore advanced stages

of the disease, differences in recording conditions and

techniques among researchers/clinicians, and other fac-

tors are possible reasons to account for this lack of sen-

sitivity (Ferraro and Ruth, 1994). Nonetheless, there isno question that this factor has limited the clinical use-

fulness of ECochG in the diagnosis of MD.

Attempts to improve the sensitivity of ECochG have

included studies designed to correlate positive findings

with symptoms at the time of testing (Ferraro et al,

1985) and manipulation of various recording parame-

ters such as stimulus type, rate, and polarity (Durrant

and Ferraro, 1991; Levine et al, 1992; Margolis et al,1992;Margolis et al, 1995; Orchik et al, 1998). Although

differences between MD and non-MD subjects were

reported under all of these conditions, data on whether

they led to an overall improvement of ECochG sensitiv-

ity were not reported.

Some of the above studies (Levine et al, 1992;Margolis

et al, 1992; Margolis et al, 1995; Orchik et al, 1998)

reported abnormal AP–N1 latency differences betweenthe electrocochleograms evoked by condensation versus

rarefaction clicks in MD patients. The rationale for this

finding was that the vibration of the cochlear partition

under hydropic conditions may be abnormally restricted

(or enhanced) in one direction over the other. As a result,

the velocity of the travelingwave (onwhich the AP–N1 is

dependent) will differ depending on whether the initial

deflection of the partition is in condensation or rarefac-tion phase. This relationship is obscured when stimuli

are presented in alternating polarity, giving way to an

SP–AP complex that appears to have a prolonged dura-

tion.Nearly 20yr earlier,Morrison and colleagues (1980)

also observed a widened SP–AP duration inMD patients

but attributed this finding to a prolonged after-ringing of

the CM under hydropic conditions. Since this earlier

study employed alternating polarity stimuli, it may belikely that Morrison and colleagues were observing

the same phenomenon as Levine and colleagues that

occurs when phase-disparate AP–N1 components from

two different waveforms are added together.

Electrocochleography Update/Ferraro

147

Regardless of the rationale for a widened SP–AP com-

plex, the above studiesmotivated us to beginmeasuring

both the amplitude and the duration of these compo-

nents to possibly improve the sensitivity of ECochGin the diagnosis ofMD.We accomplished our areameas-

urements using a special software routine from Nicolet

designed tomeasure the area under a curve defined by a

straight line connecting two cursors placed at selected

points on the ECochGwaveform. Figure 3 fromDevaiah

and colleagues (2003, p. 548) illustrates this method.

The results of our measurements yielded two studies

(Ferraro and Tibbils, 1999; Devaiah et al, 2003) thatshowed a significant improvement in ECochG’s sensi-

tivity to MD in the relatively small populations that

were studied when area values are included in the

assessment. After 5 yr of collecting data that included

area measurements we recently performed a retrospec-

tive chart review of our patient database to evaluate the

sensitivity and specificity of all of the ECochG param-

eters we measure from suspected MD patients (Ferraroand Al-Momani, 2008; Al-Momani et al, 2009). In this

study, ECochG results from 178 suspected MD patients

were compared to the eventual diagnoses these individ-

uals received from their physicians. Our protocol

included recording ECochG to broadband clicks pre-

sented in alternating polarity andmeasuring the ampli-

tudes and areas of the SP and AP (from which SP/APamplitude and area ratios are derived), the absolute la-

tency of the AP–N1, and the amplitude of the SP to 1000

and 2000Hz tone bursts (two-cycle rise–fall, 10-cycle

plateau). The results of this study revealed the sensitiv-

ity and specificity of our recording protocol leading to

the diagnosis of MD to be 92% and 84%, respectively.

The sensitivity value in particular is considerably higher

than previously reported and was attributable to theinclusion of area values in our measurements, espe-

cially the SP/AP area ratio. Thus, when measuring

the area of the SP–AP complex is included in the testing

protocol, ECochG is both a highly specific and sensitive

tool for diagnosing MD.

EFFECTS OF HEARING LOSS

I n our experience, my colleagues and I have found

that patients with sensorineural hearing loss greater

than 40–50dB HL in the 1000–4000Hz range are not

good candidates for ECochG. First, the relationship

between the SP and AP is altered as threshold increases

(Asai and Mori, 1989; Mori et al, 1993), which could

affect both amplitude and area values. Second, the

reduction of component amplitudes that tends to accom-pany increased hearing loss makes both the SP and AP

difficult to identify and separate from each other in

extratympanic recordings. Finally, when hearing loss

is greater than 60db HL above 500Hz both components

may be unrecordable from the TM or at least so poorly

defined as to render ECochG ineffective for diagnosing

MD/ELH. Thus, ECochG is best applied in suspected

MD/ELH patients in the earlier stages of the disorder,when hearing (at least in the higher frequencies) may

still be normal, or in themild to lowmoderate loss range,

and not “after the fact,” when the disease and its accom-

panying hearing loss have progressed over time.

PEDIATRIC APPLICATIONS OF ECochG

We have not confined the utilization of electroco-chleographic recording approaches to adult pop-

ulations in our clinic/laboratory. Several years ago we

began studying the feasibility of ear canal recordings

in newborns and infants, primarily as a way to improve

the amplitude and thus detectability of ABR compo-

nents measured during pediatric hearing screening/

assessment procedures. These studies were motivated

by previous investigations in adult populations showingthat such improvements can be achieved by the use of

various ear canal electrodes in combination with more

conventional ABR recording procedures (Coats, 1974;

Harder and Arlinger, 1981; Lang et al, 1981; Walter

Figure 3. Measurement of the summating potential (SP)/actionpotential (AP) area ratio. On5onset of SP (baseline); N1s5onsetof the AP–N1; N1e5offset of AP–N1; bl5next point on the wave-formwhere amplitude returns to baseline. Shaded area of the trac-ing in the top panel (A) represents the total area of the SP and AP,which is divided by the area of the AP–N1 component (shaded por-tion of the tracing in the lower panel [B]) to derive the SP/AP arearatio (from Devaiah et al, 2003, p. 548).

Journal of the American Academy of Audiology/Volume 21, Number 3, 2010

148

and Blevgad, 1981; Yanz and Dodds, 1985; Durrant,

1986; Ruth, Mills, et al, 1988; Ferraro and Ferguson,

1989; Bauch and Olsen, 1990). In all of these studies,

the amplitude of wave I was substantially larger in bothnormal- and hard-of-hearing subjects when the ABR

was recorded using an ear canal (vs. a mastoid or ear-

lobe) site. Ruth, Mills, et al (1988) compared scalp and

ear canal ABR recordings in adults and demonstrated

more sensitive wave I thresholds when the secondary

electrode was seated in the ear canal. In 1989, Ferguson

and I found no differences between the thresholds of

waves I and V utilizing a forehead-to-TM electrode con-figuration (Ferraro and Ferguson, 1989). Furthermore,

both waves I and V were measurable in subjects with

hearing loss who did not display a wave I when the

ABR was recorded using a forehead-to-mastoid approach.

Our experiments with ear canal recordings in new-

borns began in 1994, when Bealer and colleagues

utilized gold foil wrapped around a pediatric sound-

delivery tube to record the ABR from the ear canal ina small sample of newborns. Comparison between fore-

head (1)-to-ear canal (–) and forehead (1)-to-mastoid

(–) recordings were made at 60 and 30dB nHL, which

are the two levels most commonly used in newborn

screening protocols. Wave I was consistently larger at

both stimulus levels and identifiable more frequently

at 30 dB nHL in the ear canal recordings. Another inter-

esting aspect of this study was that once constructed,the ear canal electrodes were easier and took less time

to apply than the scalp electrodes. Furthermore, be-

cause preparation of the ear canal merely involved

slight cleansing of the outer portion with a cotton swab

without scrubbing the site with water/alcohol/abrasive

compound, sleeping infants were less likely to awaken

during preparation.

More recently, funding from the Hall Foundation ofKansas City and the Deafness Research Foundation

supported two studies in our clinic/laboratory involving

ear canal recordings from newborns/infants. Gaddam

and I (2008) used a modified (i.e., shortened) TIPtrode

to compare ear canal and scalp ABRs in 45 newborns

who passed their newborn hearing screening. Figure

4 from this study is an illustration of the modified elec-

trode in place. Figure 5 displays a summary of our find-ings for wave I amplitude. As can be seen from this

graph, wave I from the ear canal is almost twice as large

as its mastoid counterpart at sound levels of 80 and

60dB nHL. Although the amplitude difference at

40 dB was not as dramatic, it was nonetheless statisti-

cally significant. At 20 dB, the differences were not sig-

nificantly different between the two approaches,

primarily because many of the ABRs did not displaya wave I at this level. When present, however, ear

canal–recorded wave I’s always had larger amplitudes

than their scalp-recorded counterparts. We are cur-

rently applying the ear canal approach to ABR record-

ings in our clinical pediatric populations and have found

it to be particularly helpful for identifying the I–III and

I–V interwave intervals in children with suspectedretrocochlear disorder (with or without hearing loss).

Additional research in our laboratory/clinic utilizing

an ear canal approach for pediatric auditory evoked

potential (AEP) testing has been directed at recording

the CM from this site. Riazi and I (2008) performed ear

canal CM recordings in both newborns and adults in an

effort to optimize recording parameters for this poten-

tial when it is used to help diagnose auditory neuropa-thy (AN). Normative data were collected from seven

full-term newborns and four adults with no known risk

factors for cochlear or retrocochlear disorders. Figure 6

displays the two-channel recordings from one of the

Figure 4. Illustration of the shortened TIPtrode seated in a new-born’s ear canal. The electrode cable from the evoked potentialunit attaches to the gold foil of the TIPtrode via a micro–alligatorclip (from Gaddam and Ferraro, 2008, p. 501).

Figure 5. Summary of wave I amplitude differences betweenhigh forehead (1)-to-mastoid (–) versus high forehead (1)-to-earcanal (–) auditory brain stem response recordings in 45 normallyhearing newborns at stimulus levels of 80, 60, and 40dB nHL.Wave I amplitude was significantly larger in the ear canal re-cordings (p , .01) at all three levels. Bars indicate 11SD (fromGaddam and Ferraro, 2008, p. 502).

Electrocochleography Update/Ferraro

149

newborns in this study to a 70dB nHL, 1000Hz tone

burst presented in both rarefaction (R) and condensa-

tion (C) polarities. The top four tracings (channel 1)

were recorded using a high forehead (1)-to-test ear

canal (–) electrode configuration, while the site of theinverting (–) electrode for the bottom tracings (channel

2) was the test ear mastoid. Once again, the ear canal

recordings displayed larger amplitudes than their mas-

toid counterparts, but an even more important finding

from this study is apparent in this figure. Namely, CM

is present only in record A7. In each set of two tracings

(R R and C C), the lower waveforms were recorded with

the sound tube pinched closed. Thus, what appears to beCM in these tracings actually is stimulus electromag-

netic artifact. To eliminate this artifact, we found it

necessary to apply strict recording and shielding/

grounding techniques that included enclosing the stim-

ulus transducer in a Mu-metal case, grounding this

case, and using a shielded and grounded electrode

cable. In addition, separating CM from stimulus arti-

fact was easier to do utilizing an ear canal recording siteand toneburst stimuli. Thus, our results indicated that

unless the above conditions are applied, considerable

caution must be exercised when recording and inter-

preting the CM in humans for clinical purposes (such

as in the diagnosis of AN). We currently are in the proc-

ess of assessing the validity of this claim by comparing

ear canal versus scalp recordings of CM in childrenwith

suspected/diagnosed AN. Our database remains too

limited at this time to report any findings.

CONCLUSIONS

ECochG has been a topic of considerable interest at

the University of Kansas Medical Center for over

25 yr. During this time our research in this area has

focused on ways to optimize noninvasive recording pro-

tocols, improve the sensitivity and specificity of this toolin the diagnosis of Meniere’s disease and other oto-

neurological disorders, and expand its clinical applica-

tions to include pediatric populations. Among other

things, our studies have identified the TM as the opti-

mal noninvasive ECochG recording site for adults. We

have used the TM for virtually all of our research stud-

ies and clinical recordings since 1990 and accomplish

our measurements with minimal/no discomfort to oursubjects/patients without ever damaging themembrane.

The use of SP and AP area measurements has sig-

nificantly improved the sensitivity of ECochG in the

diagnosis of MD while maintaining high specificity.

Unfortunately, the software for performing these mea-

surements is not yet commercially available. The AEP

unit we have used for several years that was equipped

with this routine (i.e., the Nicolet Spirit) has been dis-

continued, and we have devised our own program that

allows us to make these measurements from an ASCII

file. At the time of this writing, however, two different

manufacturers of AEP test instruments are planning to

add area-measuring software to their newer units.

Our recent research employing an electrocochleo-

graphic (i.e., ear canal) approach to AEP recordings in

children has yielded two important findings. First, new-

born ABR recordings can be obtained using the ear canal

as a recording site, resulting in significantly larger wave

I components than observed in more conventional (i.e.,

scalp) recordings. Second, ear canal recordings and the

use of toneburst stimuli facilitate the measurement of

the CM in newborns and young children when this com-

ponent is of interest (such as in the diagnosis of AN).

However, strict grounding/shielding approaches must

be applied to identify CM from stimulus artifact under

these conditions. Without such precautions, it is very

likely that stimulus artifact will be mistaken for CM,

leading to false-positive diagnoses.

Acknowledgments. I extend my grateful appreciation to

the myriad students who have completed research projects,

master’s theses, and doctoral dissertations in my laboratory

over the past 25 yr. Their work has led to important findings

regarding the recording and clinical applications of electro-

cochleography (ECochG). Recent funding from the Hall

Figure 6. Two-channel cochlear microphonic (CM) recordingsfrom a full-term newborn to a 1000Hz tone burst presented at70dB nHL in rarefaction (R) and condensation (C) polarities.The top four tracings (channel 1) were recorded using a high fore-head (1)-to-test ear canal (TEC) (–) electrode configuration. Thelower four tracings (channel 2) utilized the test ear mastoid(TEM) as the site for the inverting (–) electrode. The lower tracingsin each set of two (i.e., A5, B1, A6, and B2) were recorded when thesound tube was pinched shut, indicating the presence of stimuluselectromagnetic artifact in all conditions except tracing A7 (fromRiazi and Ferraro, 2008, p. 50).

Journal of the American Academy of Audiology/Volume 21, Number 3, 2010

150

Foundation of Kansas City and the Deafness Research Foun-

dation has supported our research related to the pediatric

applications of ECochG. I dedicate this essay to the memory

of Dr. Roger Ruth, a former student, close friend, and collab-

orator who recently passed away.

REFERENCES

Al-Momani MO, Ferraro JA, Gajewski B, Ator G. (2009) Improvedsensitivity of ECochG in the diagnosis of Meniere’s disease. Int JAudiol 48(11):811–819.

Aran JM, LeBert G. (1968) Les responses nerveuse cochleaireschex l’homme, image du fonctionnement de l’oreille et nouveautest d’audiometrie objectif. Rev Laryngol Otol Rhinol (Bord) 89:361–365.

AsaiH,MoriN. (1989) Changes in summating potential and actionpotential during the fluctuation of hearing in Meniere’s disease.Scand Audiol 18:13–17.

Bauch CD, OlsenWO. (1990) Comparison of ABR amplitudes withTIPtrode and mastoid electrodes. Ear Hear 11:463–467.

Bealer J, Ferraro JA, Trouba S. (1994) ABR recorded from the earcanal in neonates. Unpublished Master’s thesis, University ofKansas Medical Center, Kansas City.

Campbell KC, Harker LA, Abbas PJ. (1992) Interpretation of elec-trocochleography in Meniere’s disease and normal subjects. AnnOtol Rhinol Laryngol 101:496–500.

Coats AC. (1974) On electrocochleographic electrode design.J Acoust Soc Am 56:708–711.

Coats AC. (1981) The summating potential andMeniere’s disease.Arch Otolaryngol 107:199–208.

Coats AC. (1986) Electrocochleography: recording techniques andclinical applications. Semin Hear 7:247–266.

Cullen JK, EllisMS, Berlin CI, LousteauRJ. (1972) Human acous-tic nerve action potential recordings from the tympanicmembranewithout anesthesia. Acta Otolaryngol 74:15–22.

Dauman R, Aran JM, Sauvage RC, Portmann M. (1988) Clinicalsignificance of the summating potential inMeniere’s disease.AmJOtol 9:31–38.

Devaiah AK, Dawson KL, Ferraro JA, Ator G. (2003) Utility ofarea curve ratio: electrocochleography in early Meniere’s disease.Arch Otolaryngol Head Neck Surg 129:547–551.

Durrant JD. (1986) Observations on combined noninvasive elec-trocochleography and auditory brainstem response recording.Semin Hear 7:289–305.

Durrant JD, Dallos P. (1972) Influence of direct current polariza-tion of the cochlear partition on the summating potentials.J Acoust Soc Am 52:542–552.

Durrant JD, Gans D. (1975) Biasing of the summating potentials.Acta Otolaryngol 80:13–18.

Durrant JD, Ferraro JA. (1991) Analog model of human click-elicited SP and effects of high-pass filtering.EarHear 12:144–148.

Eggermont JJ. (1976) Summating potentials in electrocochleo-graphy: relation to hearing disorders. In: Ruben RJ, Elberling C,Salomon G, eds. Electrocochleography. Baltimore: University ParkPress, 67–87.

FerraroJA. (2000)Electrocochleography. In:RoesserRJ,ValenteM,Hosford-Dunn H, eds. Audiology: Diagnosis. New York: Thieme,425–450.

Ferraro JA. (2007) Electrocochleography. In: Roesser RJ,Valente M, Hosford-Dunn H, eds. Audiology: Diagnosis, Treat-ment Strategies andPracticeManagement. 2nd edition.NewYork:Thieme, 400–425.

Ferraro JA, Al-Momani MO. (2008) Improved sensitivity ofECochG in the diagnosis of Meniere’s disease using SP and APareameasurements.Proceedings of the XXIXth International Con-gress of Audiology. 25(A).

Ferraro JA, Arenberg IK, Hassanein RS. (1985) Electrocochleog-raphy and symptoms of inner ear dysfunction. Arch Otolaryngol111:71–74.

Ferraro JA, Best LG, Arenberg IK. (1983) The use of electroco-chleography in the diagnosis, assessment and monitoring of endo-lymphatic hydrops. Otolaryngol Clin North Am 16:69–82.

Ferraro JA, Durrant JD. (2002) Electrocochleography. In: Katz J,ed. Handbook of Clinical Audiology. New York: Lippincott, Wil-liams and Williams, 249–273.

Ferraro JA, Durrant JD. (2006) Electrocochleography in the eval-uation of patients with Meniere’s disease/endolymphatic hydrops.J Am Acad Audiol 17:45–68.

Ferraro JA, Ferguson R. (1989) Tympanic ECochG and conven-tional ABR: a combined approach for the identification of waveI and the I–V interwave interval. Ear Hear 10:161–166.

Ferraro JA, Krishnan G. (1997) Cochlear potentials in clinicalaudiology. Audiol Neurootol 2:241–256.

Ferraro JA, RuthRA. (1994) Electrocochleography. In: Jacobson J,ed. Auditory Evoked Potentials: Overview and Basic Principles.Boston: Allyn and Bacon, 101–122.

Ferraro JA, Thedinger B, Mediavilla SJ, Blackwell W. (1994)Human summating potential to tonebursts: observations on TMversus promontory recordings in the same patient. J Am AcadAudiol 5:24–29.

Ferraro JA, Tibbils R. (1999) SP/AP area ratio in the diagnosis ofMeniere’s disease. Am J Audiol 8:21–28.

Gaddam A, Ferraro JA. (2008) ABR recordings in newborns usingan ear canal electrode. Int J Audiol 47:499–504.

Gibson WPR, Moffat DA, Ramsden RT. (1977) Clinical electroco-chleography in the diagnosis and management of Meniere’s disor-der. Audiology 16:389–401.

Goin DW, Staller SJ, Asher DL, Mischke RE. (1982) Summatingpotential in Meniere’s disease. Laryngoscope 92:1383–1389.

Harder H, Arlinger S. (1981) Ear canal compared to mastoid elec-trode placement in ABR. Scand Audiol Suppl 13:55–57.

Kitahara M, Takeda T, Yazama T. (1981) Electrocochleography inthe diagnosis of Meniere’s disease. In: Volsteen KH, ed. Meniere’sDisease, Pathogenesis, Diagnosis and Treatment. New York:Thieme-Stratton, 163–169.

Kumagami H, Nishida H, Masaaki B. (1982) Electrocochleo-graphic study of Meniere’s disease. Arch Otolaryngol 108:284–288.

Lang AH, Happonen JM, Salmivalli A. (1981) An improved tech-nique for the non-invasive recording of auditory brain-stem

Electrocochleography Update/Ferraro

151

responses with a specially constructed meatal electrode. ScandAudiol 13(Suppl.):59–62.

Levine SC, Margolis RH, Fournier EM, Winzenburg SM. (1992)Tympanic electrocochleography for evaluation of endolymphatichydrops. Laryngoscope 102:614–622.

Margolis RH, Levine SM, Fournier MA, Hunter LL, Smith SL,Lilly DJ. (1992) Tympanic electrocochleography: normal andabnormal patterns of response. Audiology 31:8–24.

Margolis RH, Rieks D, Fournier M, Levine SM. (1995) Tympanicelectrocochleography for diagnosis of Meniere’s disease. Arch Oto-laryngol Head Neck Surg 121:44–55.

Mori N, Asai H, SakagamiM. (1993) The role of summating poten-tial in the diagnosis and management of Meniere’s disease. ActaOtolaryngol (Stockh) 501(Suppl.):51–53.

Morrison AW,Moffat DA, O’Connor AF. (1980) Clinical usefulnessof electrocochleography in Meniere’s disease: an analysis of dehy-drating agents. Otolaryngol Clin North Am 13:703–721.

Murphy LA, Ferraro JA, Chertoff M, McCall S, Park D. (1997)Issues in auditory evoked potentials. In: 1997 American Academyof Audiology Convention Program. American Academy of Audiol-ogy, 64(A).

Orchik DJ, Ge NN, Shea JJ. (1998) Action potential latency shiftby rarefaction and condensation clicks in Meniere’s disease. J AmAcad Audiol 9:121–126.

Pou AM, Hirsch BE, Durrant JD, Gold SR, Kamerer DB. (1996)Efficacy of tympanic electrocochleography in the diagnosis of endo-lymphatic hydrops. Am J Otol 17:607–611.

Riazi M, Ferraro JA. (2008) Observations on mastoid versus earcanal recorded cochlear microphonic in newborns and adults.J Am Acad Audiol 19:46–55.

Ruben R, Bordley JE, Nager GT, Sekula J, Knickerbocker GG,Fisch U. (1960) Human cochlear responses to sound stimuli.Ann Otol Rhinol Laryngol 69:459–479.

Ruth RA. (1990) Trends in electrocochleography. J Am AcadAudiol 1:134–137.

RuthRA. (1994) Electrocochleography. In: Katz J, ed.Handbook ofClinical Audiology. 4th edition. Baltimore: Williams and Wilkins,339–350.

Ruth RA, Lambert PR, Ferraro JA. (1988) Electrocochleography:methods and clinical applications. Am J Otol 9:1–11.

Ruth RA, Mills JA, Ferraro JA. (1988) Use of disposable ear canalelectrodes in auditory brainstem response testing. Am J Otol 9:310–315.

Schmidt PH, Eggermont JJ, Odenthal DW. (1974) Study ofMeniere’s disease by electrocochleography. Acta Otolaryngol(Suppl. 316):75–84.

Staller S. (1986) Electrocochleography in the diagnosis and man-agement of Meniere’s disease. Semin Hear 7:267–277.

Stypulkowski PH, Staller SJ. (1987) Clinical evaluation of a newECoG recording electrode. Ear Hear 8:304–310.

Walter B, Blevgad B. (1981) ABR following severe head trauma. Astudy of click-evoked and frequency-following responses. ScandAudiol Suppl 13:125–130.

Yanz J, Dodds R. (1985) An ear-canal electrode for the measure-ment of the human auditory brainstem response. Ear Hear 6:98–104.

Yoshie N, Ohashi T, Suzuki T. (1967) Non-surgical recording ofauditory nerve action potentials in man. Laryngoscope 77:76–85.

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