Gold Standard Books

[Armonia Bunda]

The Testing Standards are a product of the American Educational Research Association, the American Psychological Association (APA), and the National Council on Measurement in Education (NCME). Published collaboratively by the three organizations since 1966, it represents the gold standard in guidance on testing in the United States and in many other countries. Read more

To order the previous edition of Standards (1999), please use the mail/fax order form (PDF) available on the left-hand side of the page under the Books tab. Downloadable files are also available here.

Hearing loss is a common condition that affects millions of people regardless of age, ethnicity, and health status. Appropriate treatment for hearing loss depends greatly on the underlying pathophysiology and the severity of the condition. Pure-tone audiometry is a critical means of obtaining diagnostic information to guide healthcare providers toward appropriate treatment. Appropriate treatment for hearing loss depends significantly on the pathophysiology and the severity of the condition, and a detailed hearing assessment provides the healthcare team with the necessary diagnostic information to guide treatment. This activity reviews the details of pure-tone audiometry evaluation, including clinical appropriateness and utility, and examines the role of the interprofessional team in the evaluation and management of patients with otologic complaints.

Objectives:Explain the difference between air conduction and bone conduction pure-tone evaluation.Describe the clinical utility of pure-tone audiometric threshold assessment.Identify when a clinically significant asymmetry of pure-tone thresholds is present.Review when pure-tone audiometry evaluation is or is not an appropriate method to assess hearing status.Access free multiple choice questions on this topic.

Hearing loss is a widespread chronic condition that affects over 25 million people in the United States aged 12 years old or older and may affect 1 in 5 children, temporarily or permanently, by the age of 18.[1][2] Despite the high prevalence of hearing loss, many adults do not receive appropriate or timely evaluation and treatment for their hearing concerns.[3] Appropriate treatment for hearing loss depends greatly on the pathophysiology and the severity of the condition, and a detailed hearing assessment provides the healthcare team with the necessary diagnostic information to guide treatment.

While Weber and Rinne tuning fork tests are useful for clinical screening and identifying the type of hearing loss, they may miss nuances such as mild hearing loss, bilateral hearing loss, or mixed conductive and sensorineural hearing loss.[4][5] Pure-tone (isolated frequency) audiometry evaluation over the range of frequencies important for everyday listening can determine the degree, configuration, and type of hearing loss in a manner detailed enough to assist the healthcare team in determining the etiology and prognosis for the hearing loss as well as the optimal treatment strategy.[6]

Pure-tone testing assesses the auditory system through two pathways. In air conduction (AC) testing, sound waves enter the external auditory canal and pass through the tympanic membrane, ossicular chain, and cochlea to reach the cochlear nerve (part of cranial nerve VIII) and then travel through the brainstem to the auditory cortex. In bone conduction (BC) testing, sound waves are introduced directly to the cochlea through the vibration of a bone conduction oscillator on the mastoid process.[7]

By utilizing both methods of pure-tone testing, hearing loss is determined to be conductive (involving the pinna through the ossicular chain), sensorineural (involving the cochlea to the auditory cortex), or mixed (both conductive and sensorineural involvement).[8] For some patients, a false "conductive" component may appear in the presence of "third-window" pathologies like semicircular canal dehiscence because of changes in sound transmission from the dehiscence.[9] Third window phenomena are referred to as such because they function as third connections between the inner and middle ears when counted along with the oval and round windows.

Pure-tone evaluation should be performed for patients concerned about abnormal auditory perception, ear trauma, or otologic disease.[10] This includes, but is not limited to: subjective hearing loss, tinnitus, hyperacusis, ototoxic monitoring protocols, dizziness or vertigo, middle ear dysfunction, traumatic brain injury or temporal bone fracture, loud noise exposure, blast injury, failed hearing screening, speech delay in children, or conditions with risk factors for hearing loss.[11][12]

A reliable pure-tone evaluation cannot be completed if a patient cannot provide reliable behavioral responses.[13] This is particularly true of children under six months of age but is also seen in patients with developmental delays or neurological impairment. Behavioral pure-tone testing may also be contraindicated if unreliable responses are given by patients who are malingering or who have factitious disorders.[14] In these circumstances, objective electrophysiologic or otoacoustic emission testing instead of behavioral responses is necessary to build a complete clinical picture.[15]

Pure-tone evaluation is typically performed in a sound-treated booth to reduce the impact of external sounds, with the booth environment and electroacoustic equipment calibrated to American National Standards Institute (ANSI) standards to optimize inter-test and intra-test reliability. Audiometers generate the sounds presented for testing, controlling the pitch, loudness, transducer type, and ear of presentation.[16]

Various transducers may be used depending on the auditory pathway being assessed and the anatomical limitations of the ears. Standard electroacoustic transducers for pure-tone audiometry are supra-aural headphones, insert earphones, circumaural headphones, and bone conduction oscillators.[17][18] Speakers aligned at 90 or 45 degrees from the testing seat are used for children who cannot tolerate headphones. The presented tones are warbled in such a sound-field environment to avoid standing waves from a single pure-tone frequency.[19] Sound field testing evaluates the composite best hearing ear, which means that the threshold recorded will be the quietest sound audible by either ear at each frequency presented. A normal sound-field audiogram, therefore, does not indicate normal hearing across all tested frequencies in both ears but rather that at each tested frequency, at least one of the ears could hear the tone normally. On the other hand, because recorded thresholds in sound-field audiometry indicate the acuity of the better-hearing ear, if a hearing loss is encountered, that elevated threshold represents the hearing loss in the better-hearing ear; there may or may not be worse hearing in the other ear. For this reason, individual ear testing to rule out unilateral hearing loss cannot be obtained with sound-field audiometry.

Regardless of the method of presenting the tones, patient responses are typically given with a button, a hand raise, or a verbal acknowledgment, with adaptations made for children unable to give a deliberate response with reliability.[20][21] These adaptation techniques are called visual reinforcement audiometry and conditioned play audiometry, both of which use structured play-like stimuli-and-response with toys to obtain more reliable information.[22]

Pure-tone screenings, such as in schools or inpatient hospital environments, are performed with calibrated portable audiometers that may test air and bone conduction or air conduction only, depending on the model.[23] Screenings assess for awareness of a minimum response level at a limited set of frequencies to determine if further diagnostic evaluation is warranted.[24] Standard pure-tone assessment with a portable audiometer using a precise transducer set-up and performed in a sufficiently quiet environment can obtain comparable threshold accuracy to sound booth assessments.[16]

When pure-tone testing is indicated for evaluation of a specific complaint, the procedure is typically performed by an audiologist; however, screening audiometry (as is commonly used for school-aged children and military personnel) may be performed using automated testing equipment by an audiology technician.

For diagnostic pure-tone testing, patients are seated in a sound booth and counseled regarding the testing method and expected response. With young children, parents are instructed on how the behavioral testing will occur, typically with the patient seated in the parent's lap. A young child may receive basic instructions to assist in understanding and comfort with the test procedure.

The audiologist will place appropriate transducers on the patient's head or ears before closing the sound booth door and relocating to an adjacent booth to control the audiometer. The audiologist can observe the patient through an insulated window and hear feedback from the patient via a microphone inside the booth.

Results are recorded on a graph known as the audiogram, which logarithmically plots sound frequency in cycles per second (Hertz or Hz) from low pitch to high pitch along the X-axis and loudness in decibels of hearing level (dB HL) from soft to loud along a reversed Y-axis.[25] Decibels of hearing level differ from decibels of sound pressure level because the use of hearing level reflects the fact that normal human ears hear better in the middle-frequency ranges than at the higher and lower frequencies and thus normalizes the scale using an isophonic curve. For example, a 0 dB hearing level (normal hearing) at 500 Hz is equivalent to a 13.5 dB sound pressure level, according to ANSI S3.6-1996. At 1000 Hz, 0 dB HL equals 7.5 dB SPL, and at 2000 Hz, 0 dB HL equals 9 dB SPL. Down at 125 Hz, however, 0 dB HL equals 45 dB SPL, and up at 8000 Hz, 0 dB HL is 15.5 dB SPL.

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