**Contralateral Suppression of Otoacoustic Emissions: Working Towards a Simple Objective Frequency Specific Test for Hearing Screening**

Nikolaus E. Wolter1, Robert V. Harrison2 and Adrian L. James3

*1Department Otolaryngology, Head and Neck Surgery, University of Toronto 2Hospital for Sick Children, Department of Otolaryngology – Head and Neck Surgery, Department of Neurosciences and Mental Health, University of Toronto 3Hospital for Sick Children, Department of Otolaryngology – Head and Neck Surgery, University of Toronto Canada* 

#### **1. Introduction**

24 Hearing Loss

Killion, MC. (1997). Hearing aids: Past, present, future and moving toward normal

Loizou, PC. (1998). Introduction to cochlear implants. *IEEE Signal Processing Mag*, ISSN:0739-

Madsen Electronics. (2004). 922Orbiter In: *Operation Manual of Clinical Audiometer*. MADSEN,

MAICO. (2007). Operating Instructions Race Car Tympanometer. 1162-0703 Rev A, pp.4-15. Marullo, T.; Mazza, G. & Bianchi, F. (1967). Evaluation of vocal acumetry. *PubMed:* 5612940,

Medical Advisory Secretariat. (2002). Bone anchored hearing aid: an evidence based analysis. Ontario Health Technology Assessment Series Vol. 2, No.3 Medical Service Advisory Committe. (2010). Middle ear implant for sensorineural, conductie

Miller, G. (2006). *Sensory Organ Replacement and Repair*, (1st Edition), Ed Morgan & Claypool

Montano, J. & Spitzer, J. (2009). *Adult Audiologic Rehabilitation*, Ed Plural Publishing, ISBN:

National Health and Nutrition Examination Survey. (2003). Audiometry Procedures

Penhaker, M. & Kijonka J. (2011). Audiometry for Teaching Experiment in

Phillips, W.; Knight, L.; Caldwell, N. & Warrington, J. (2007). Policy through procurement—

Preves, D. & Banerjee, S. (2008). Hearing aid instrumentation signal processing and

Spitzer, JB. (2010) Implantable Devices for Rehabilitation of Persons with Hearing Loss. In :

Steele, CH.; Baker, G.; Tolomeo, J. & Zetes-Tolomeo D. (2000). Cochlear Mechanics, In: *The* 

Walden, T. & Walden, B. (2004). Predicting success with hearing aids in everyday living.

Roeser, R., pp.(1–35), Thieme Medical, New York USA, ISBN:978-3-13 Salesa, E.; Bonavida, A. & Perelló, J. (2005). *Tratado de Audiología*, (1a Edición), Elsevier-

PowerLabSystems, In: Electrical Power Systems and Computers, Xiaofeng W,

The introduction of digital signal process (DSP) hearing aids into the English NHS.

electroacoustic testing. In: *Audiology treatment,* Valente, M.; Hosford-Dunn, H. &

*Implantable Technologies. Seminars in Hearing*, Spitzer JB., pp.(3-6), Thieme-Stratton,

*Biomedical Engineering Handbook*, Bronzino, J., pp. (581-594), CRC IEEE PRESS, ISBN

*Journal of the American Academy of Audiology,* Vo. 15, No. 5, pp. (342–352), ISSN:1050-

Vol. 43 No. 4, (August 1967), pp.(217-243),ISSN:0899-8205

Publishers' Series, ISBN:1598290630, San Rafael, CA USA

pp.(831-838), Springer-Verlag, ISBN:978-3-642-21746-3, Berlín

*Health Policy*, Vol. 4, No. 1, pp.(77–85), ISSN:0168-8510

Masson., ISBN: 844581554-7, Madrid España

New York USA, ISSN:0734-0451

0545

0-8493-0461-X, Boca Raton Florida USA

pp.(141–148), ISSN:0300-5364

Denmark

978-1-74241-348-8

5175, (September 1998), pp.(101–130)

9781597562508, San Diego, CA USA

Manual, (January 2003), pp.(2.1-2.55)

conversation in noise. *British Journal of Audiology,* Vol. 31, No. 3, (October 1997),

pp.(102-105), Version 2.X. Part No.7-26-110, Doc. No. 7-26-1100/0, Copenhagen,

and mixed hearing losses, Cormmonwalth of Australia, (November, 2010), ISBN:

Hearing loss affects all demographics regardless of geographical location or age. In a similar fashion to how hearing loss can isolate post-lingualy deaf adults, hearing loss in the pediatric population has profound detrimental effects despite the richness of the deaf culture. A complete discussion of the adverse effects of hearing loss must include discussion of this important component of the deaf and hearing impaired population. The World Health Organization defines "disabling hearing impairment" in children under the age of 15 years as an unaided hearing threshold level in the better ear of 31 dB HL or more using pure tone averages at 0.5, 1, 2 and 4 kHz. The prevalence of childhood hearing loss is 1.2 to 1.7 cases per 1000 live births and the prevalence increases up to 6 years of age as a result of meningitis, delayed onset of genetic hearing loss, or delayed diagnosis (Kral & O'Donoghue, 2010). In the majority of cases of childhood hearing loss is congenital with a smaller proportion being progressive or acquired (A. Davis & Wood, 1992; A. Davis et al., 1997).The prevalence is greater still in developing countries because of lack of immunization, exposure to ototoxic drugs, and consanguinity (Kral & O'Donoghue, 2010). Profound hearing loss (hearing loss > 90 dB) has far-reaching, lifelong consequences in children (Kral & O'Donoghue, 2010). Andrej *et al*. report that there can be a restriction in learning and literacy as a result of the lack of development of spoken language with its impact on daily communication (Kral & O'Donoghue, 2010; Marschark & Wauters, 2008). This in turn has been shown to substantially compromise educational achievement and employment opportunity later in life (Allen, 1986; A. Davis et al., 1997; Schroeder et al., 2006; Thompson et al., 2001; Wake, Hughes, Poulakis, Collins, & Rickards, 2004a). The detrimental effects of profound hearing loss in children are summarized in Table 1. Unless children are afforded opportunities to develop language, deaf children can fall behind their hearing peers in communication, cognition, literacy and psychosocial development (Holden-Pitt & Albertorio, 1998).

Contralateral Suppression of Otoacoustic Emissions:

system as a potential new screening method.

**Extracorporeal membrane oxygenation** 

**Neonatal intensive care unit admission for > 5 days** 

\*(Busa et al., 2007; Manchaiah, Zhao, Danesh, & Duprey, 2011)

Table 2. Risk factors for childhood hearing loss\*

**2. Existing neonatal hearing tests** 

**2.1 Auditory evoked potentials** 

Table 3.

syndrome, Usher syndrome

**Family history of hearing loss Neonatal hyperbilirubinemia** 

syndrome

Tooth syndrome

**Chemotherapy Consanguinity** 

**Genetic mutations** 

**Trauma** 

Working Towards a Simple Objective Frequency Specific Test for Hearing Screening 27

overview of existing neonatal hearing screening tests and use of the medial olivocochlear

**Syndromes known to be associated with sensorineural hearing loss**: Brancho-oto-renal

**Craniofacial syndromes**: Crouzon disease, Klippel-Feil syndrome, and Goldenhar

syndrome, Pendred syndrome, Wardenburg syndrome, Treacher-Collins, Stickler

**Neurodegenerative disorders**: Hunter syndrome, Friedrich's ataxia, Charcot-Marie-

**Infection and neonatal sepsis:** CMV**,** measles, mumps, rubella, *H influenzae* type b, and

The difficulty of testing young individuals using subjective methods has lead to the development of hearing testing based on objective methods such as otoacoustic emissions

Measurement of auditory evoked potentials (AEP) has been possible since the 1960s. AEPs represent electrical activity occurring along the length of the auditory pathway. They are typically described by their latency from the onset of the auditory stimulus: early (0 to 15 milliseconds), middle (15 to 100 milliseconds) and late (100 to 500 milliseconds). Auditory brainstem responses (ABR) appear to be the most clinically useful early latency AEPs for detecting hearing loss in newborns and infants ( Hecox 1974). Hecox *et al.* first speculated on the use of Auditory Brainstem Responses (ABR) as an objective method of assessing infant hearing in 1974 (Hecox & Galambos, 1974). Measurement of ABR makes use of the summation of action potentials from the cochlear nerve to the inferior colliculus of the midbrain in response to a click stimulus applied to the test ear. Since that time the use of ABR has become a widely accepted method to assess auditory function and hearing sensitivity. The commonly cited advantages and disadvantages of ABR are summarized in

childhood meningitis, toxoplasmosis, herpes, syphilis, bacterial meningitis

and auditory brainstem response testing (James, 2011; Thompson et al., 2001).


\*(Allen, 1986; A. Davis et al., 1997; Kral & O'Donoghue, 2010; Marschark & Wauters, 2008; Schroeder et al., 2006; Thompson et al., 2001; Wake, Hughes, Poulakis, Collins, & Rickards, 2004a)

#### Table 1. Detrimental Effects of Profound Hearing Loss in Childhood\*

The widespread use of universal neonatal hearing screening has been established based on the growing body of evidence that early detection of hearing loss leads to early aural rehabilitation (Kennedy, McCann, Campbell, Kimm, & Thornton, 2005). Multiple studies have demonstrated the deleterious effect of bilateral hearing loss on speech and language development (Allen, 1986; A. Davis et al., 1997; Thompson et al., 2001; Wake, Hughes, Poulakis, Collins, & Rickards, 2004b). However if caught early, the effects of hearing loss are somewhat mitigated. Yoshinaga-Itano *et al.* reported on the ability of early detection of hearing loss to improve language development as measured by standardized testing (Yoshinaga-Itano, Sedey, Coulter, & Mehl, 1998; Yoshinaga-Itano, 2003). Children enrolled into language programs at earlier ages have improved vocabulary and verbal reasoning skills on standardized tests at 5 years of age (Moeller, 2000) Opponents to Universal screening cite the great cost of such widespread screening as well as efficacy in earlier years. From a pragmatic, fiduciary perspective, a cost-effectiveness study has shown that as a result of special education needs, failure to detect severe-to-profound hearing loss can cost the educational system approximately \$38 000 – 240 000 (USD) per child over their educational lifetime (Mohr et al., 2000). It would seem then that detecting these children would offset a significant amount of the cost. Furthermore, in areas that have adapted a Universal Newborn Hearing protocol, detection of congenital hearing loss has nearly doubled since its introduction (Choo & Meinzen-Derr, 2010).

It is clear that the early detection of hearing loss has strong developmental, psychosocial and societal implications as well. Therefore, in 2007 the American Academy of Pediatrics' Joint Committee on Infant hearing endorsed the early detection of hearing loss with an aim at early intervention to improve linguistic competence and literary development (Busa et al., 2007). They recommended that all infants should be screened prior to 1 month of age. Children identified with hearing loss by screening should have a comprehensive audiological assessment by 3 months of age. After audiological assessment, children with confirmed hearing loss should receive appropriate intervention by dedicated hearing loss health care and education professionals not later than 6 months of age. Children with risk factors for hearing loss (a summary of commonly cited risk factors can be found in Table 2.) should be followed by on-going surveillance starting at 2 months of age. Unfortunately in many centers the "lost to follow up" rates approach 40% of infants who do not pass their infant screening (Choo & Meinzen-Derr, 2010). All centers must work diligently to ensure children who fail their hearing screen are referred appropriately to maximize their potential and mitigate the lifelong effects of hearing loss. The following sections will provide an overview of existing neonatal hearing screening tests and use of the medial olivocochlear system as a potential new screening method.


\*(Busa et al., 2007; Manchaiah, Zhao, Danesh, & Duprey, 2011)

Table 2. Risk factors for childhood hearing loss\*
