Hearing loss is the result of impaired auditory sensitivity and/or diminished speech intelligibility of the physiological auditory system. Individuals with hearing loss are sometimes described as deaf or hard of hearing based on the type, degree, and configuration of hearing impairment.
There are three basic types of hearing loss: sensorineural, conductive, and mixed.
Sensorineural hearing loss (SNHL) is hearing loss due to cochlear (sensory) or VIIIth nerve (neural) auditory dysfunction. Most of the time, SNHL cannot be medically or surgically corrected. Presbycusis is a sensorineural hearing loss that occurs gradually, later in life, affecting hearing in both ears over time. The loss associated with presbycusis is usually greater for high-pitched sounds.
Conductive hearing loss occurs when there is a problem conducting sound waves easily through the outer ear canal, tympanic membrane, or middle ear (ossicles). Conductive hearing loss makes sounds softer and more difficult to hear. This type of hearing loss may be responsive to medical or surgical treatment.
Mixed hearing loss is the result of damage to conductive pathways of the outer and/or middle ear and to the nerves or sensory hair cells of the inner ear.
Degree of hearing loss refers to the severity of the loss. The table below shows one of the more commonly used classification systems.
|Degree of hearing loss||Hearing loss range (dB HL)|
|Normal||–10 to 15|
|Slight||16 to 25|
|Mild||26 to 40|
|Moderate||41 to 55|
|Moderately severe||56 to 70|
|Severe||71 to 90|
Adapted from Clark, 1981.
The degree of hearing loss can have significant implications for children with hearing loss, as even a slight hearing loss can be educationally significant for children in the school setting. Educationally significant hearing loss has been defined as "any hearing loss that potentially interferes with access to classroom instruction and impacts a child or youth's ability to communicate, learn and develop peer relationships (Johnson & Seaton, 2012, p. 43).
The configuration, or shape, of the hearing loss refers to the degree and pattern of hearing loss across frequencies (tones), as illustrated in a graph called an audiogram. For example, a hearing loss that affects only the high tones would be described as a high-frequency loss. Its configuration would show good hearing in the low tones and poor hearing in the high tones. On the other hand, if only the low frequencies were affected, the configuration would show poorer hearing for low tones and better hearing for high tones. Some hearing loss configurations are flat, indicating the same amount of hearing loss for low and high tones.
In addition, hearing loss may be bilateral or unilateral, symmetrical (degree and configuration of hearing loss are the same in each ear) or asymmetrical, progressive or sudden in onset, and fluctuating or stable.
Note: The scope of this content is limited to the diagnosis and management of hearing loss for individuals ages 5 years and older from an audiological perspective. Resources for hearing screening and habilitation are under development. See the permanent childhood hearing loss page for information on hearing loss for children from infancy through age 5.
Prevalence of hearing loss increases dramatically with age. National survey results show that in the population of those with hearing impairment, only 2% were born with a hearing impairment; 4% to 6% developed a hearing loss after birth and before 6 years; 11% to 12% developed hearing loss between ages 6 and 19 years; 50% to 64% developed hearing loss between ages 20 and 59 years; and 20% to 30% developed hearing loss at or after the age of 60 (data from the National Health Interview Survey, 2007, retrieved from the National Institute on Deafness and Other Communication Disorders [NIDCD], 2010).
Findings from the National Health and Nutrition Examination Survey indicated that 14.9% of children between 6 and 19 years of age had a hearing loss of at least 16 dB in either low or high frequencies; the majority of these losses were classified as slight (16-25 dB; Niskar et al., 1998). Hearing loss of at least 25 dB at the speech frequencies has been reported in 29% of adults 50-59 years old, in 49% of adults 60-69 years old, and in 63.1% of adults ages 70+ (Agrawal, Platz, & Niparko, 2008; Lin, Thorpe, Gordon-Salant, & Ferrucci, 2011).
Signs and symptoms associated with hearing loss-including behaviors of affected individuals-include
Signs and symptoms in school-age children also include
Not all patients will experience each symptom.
Causes of conductive hearing loss include
Mixed hearing loss is caused by a combination of one or more causes of conductive hearing loss and one or more causes of sensorineural hearing loss.
Causes of sensorineural hearing loss include:
Approximately one-third of Americans between ages 65 and 74 and nearly half over the age of 75 have hearing loss (NIDCD, 2010). Many older adults will have both hearing impairment and cognitive loss, and together these losses will affect communication, social participation, and quality of life (Pichora-Fuller, Dupuis, Reed, & Lemke, 2013).
Lin et al. (2013) found that individuals with baseline hearing loss had greater rates of cognitive decline over time than did individuals with normal hearing. Further investigation is needed to clarify this relationship and to determine whether hearing loss is a risk factor for dementia or a sign of early-stage dementia. One hypothesis is that when a hearing loss is present, greater cognitive resources are dedicated to auditory processing, leaving fewer resources for other cognitive processes, like working memory (Peelle, Troiani, Grossman, & Wingfield, 2011). Recent research suggests the possibility of a shared etiological pathway responsible for both hearing loss and dementia (Gallacher et al., 2012).
It is important for clinicians to differentiate between hearing loss and cognitive impairment and to identify when one or both of these conditions are present. See dementia.
Audiologists play a central role in the screening, assessment, diagnosis, and treatment of persons with hearing loss. The professional roles and activities in audiology include clinical/educational services (diagnosis, assessment, planning, and treatment), prevention and advocacy, education, administration, and research. See ASHA's Scope of Practice in Audiology (ASHA, 2018).
Appropriate roles for audiologists include:
As indicated in the Code of Ethics (ASHA, 2010), audiologists who serve this population should be specifically educated and appropriately trained to do so.
Speech-language pathologists (SLPs) play a role in the identification, screening, assessment, and rehabilitation of individuals with hearing loss and refer individuals suspected of having hearing loss to an audiologist for a complete audiologic assessment. Professional roles and activities in speech-language pathology include clinical/educational services, prevention and advocacy, education, administration, and research. See ASHA's Scope of Practice in Speech-Language Pathology (ASHA, 2016). As indicated in the Code of Ethics (ASHA, 2010), SLPs who serve this population should be specifically educated and appropriately trained to do so.
SLPs have the specialized preparation, experiences, and opportunities to address communication effectiveness, disorders, differences, and delays that result from a variety of factors, including those that may be related to hearing loss. SLPs have the knowledge and skills to address the complex interplay of the areas of listening, speaking, signing, reading, writing, and thinking. Furthermore, they understand how skill expansion in one of these components enhances performance in another area, ultimately contributing to the overall development of literacy and learning.
Appropriate roles for speech language pathologists include:
The purpose of the audiologic assessment is to
Audiologic assessment typically includes
Additional tests may include
Accurate diagnosis of hearing loss relies on the audiologist's interpretation of a test battery within the context of the individual's medical and/or developmental history. Case history information may indicate a need for modification of evaluation procedures. For example, the audiologist may include evaluation of the high-frequency region of the cochlea (above 4000 Hz) for an individual with a history of ototoxic drug exposure. Modification of routine assessment procedures also may be necessary to adequately evaluate individuals with multiple disabilities.
Examples of questions that might typically be included on a case history are listed below. The specific questions may vary, based on the age and circumstances of the patient.
Case history typically includes information related to
Case history is recorded using a standard format. See the cultural competence Practice Portal page for information regarding gathering a case history.
Visual inspection of the pinna and ear canal, including otoscopy, precedes audiometric testing to rule out active pathological conditions and the potential for ear canal collapse caused by audiometric earphones. The audiologist ensures that the external auditory canal is free of excessive cerumen before testing.
Acoustic immittance testing is useful in localizing the site of lesion for the hearing loss. Acoustic immittance testing may include tympanometry and/or acoustic reflex testing.
Tympanometry is performed with a 226 Hz probe signal. Parameters of tympanograms to be investigated include
A tympanogram is a graphic representation of the relationship of acoustic impedance and air pressure of the middle ear and the mobility of the tympanic membrane. Various middle ear pathologies (otitis media, otosclerosis, and tympanic membrane perforations) yield distinctive tympanograms. Compliance is plotted vertically on the tympanogram and is measured in ml or mmho. Maximum compliance of the middle ear system occurs when the pressure in the middle ear cavity is equal to the pressure in the external auditory canal. The maximum compliance value (static acoustic admittance) occurs at the highest peak of the curve on the graph (Figure 1). Pressure is indicated on the horizontal axis of the graph and is measured in decapascals.
Figure 1. Tympanogram Showing Maximum Peak Compliance
There are three main types of tympanograms: A, B, and C. In a Type A tympanogram, peak compliance occurs at or near atmospheric pressure, indicating a normal middle ear system, free of fluid or physiological anomalies that would prevent the admittance of sound from the middle ear into the cochlea. Figure 1 shows an example of a Type A tympanogram.
Type B tympanograms have no sharp peak and little or no variation in impedance over a wide sweep range. A Type B tympanogram (Figure 2) is indicative of middle ear pathology, such as fluid or infection behind the tympanic membrane. In some cases, these tympanograms are seen when there is a hole in the tympanic membrane with the difference being the ear canal volume: a larger ear canal volume indicates a perforation in the tympanic membrane.
Figure 2. Type B Tympanogram
Type C tympanograms (Figure 3) are similar in shape to Type A tympanograms, but are shifted negatively on the graph, with peak compliance significantly below zero (usually less than -200), indicating negative pressure within the middle ear space. This finding is often consistent with sinus or allergy congestion or the end-stages of a cold or otitis media.
Figure 3. Type C Tympanogram
Ipsilateral and contralateral acoustic reflexes are performed to assess the integrity of the acoustic reflex pathway. Acoustic reflex thresholds (ARTs) are measured at 500, 1000, and 2000 Hz. Testing at 4000 Hz is not recommended, because many people with normal hearing have elevated reflexes at this frequency (Gelfand, 1984; Silman & Silverman, 1991).
Normal ARTs range from about 85 to 100 dB SPL for pure tone stimuli (Gelfand, 1984).
Acoustic reflex decay is the reduction in the magnitude of the acoustic reflex during a prolonged stimulus. Reflex decay is measured at 500 and 1000 Hz only, because rapid adaptation is common at higher stimulus frequencies. Reflex decay is typically measured contralaterally. Reflex decay is abnormal if the reflex is reduced more than 50% over the first 10 seconds. Abnormal reflex decay is associated with retrocochlear pathologies.
Otoacoustic emissions (OAEs) are used to assess cochlear function and are useful in differential diagnosis. OAEs are best measured in a quiet environment (e.g., in a quiet room with no one speaking and minimal background noise). A snug probe fit is essential for valid and reliable recordings. Ears are tested one at a time. Acceptable OAE protocols include
The audiologist is responsible for ensuring regulatory compliance prior to conducting testing. Regulatory requirements identify specifics and required documentation. Familiarization to the test tone before threshold measurement is not recommended.
If unilateral hearing loss is suspected, the audiologist uses appropriate masking, rules out testing errors, and verifies proper function of the audiometer and transducers. In instances of atypical threshold responses, such as identical thresholds in both ears or unusual configurations, the audiologist considers reinstruction and/or retest to verify threshold accuracy and verifies proper function of the audiometer and transducers.
Stimuli: Continuous, warble or pulsed tone signals are used. Pulsed tones have been shown to increase a test participant's awareness of the stimuli (Burk & Wiley, 2004).
Transducer: Earphones (supra-aural, circumaural, and insert) used for pure tone audiometry shall be appropriate to the test technique used. Transducers are matched to the audiometer and should not be interchanged without recalibration. Supra-aural and insert earphones are appropriate for air-conduction threshold measurements from 125 Hz through 8000 Hz, while circumaural earphones are used for extended high-frequency measurements within their respective frequency and intensity response ranges.
When abrupt differences of 20 dB or more occur between adjacent octave frequencies, additional frequencies may be added at the discretion of the tester (ANSI, 2009).
Order: The better ear, when known, is tested first. Initial test frequency is typically 1000 Hz. Following the initial test frequency, the audiologist tests at, in order, 2000, 3000, 4000, 6000, and 8000 Hz, followed by a retest of 1000 Hz before testing at 500, 250, and 125 Hz. A retest at 1000 Hz is not necessary when testing the second ear. Presentation order of frequencies does not significantly influence test results (ANSI, 2009). The above order is an arbitrary choice that will ensure consistency of approach and minimize risk of omissions.
Masking: Air-conduction pure tone audiometry can be confounded by crossover or contralateralization of the signal, which occurs when a signal presented to one ear, if it is of sufficient magnitude, is perceived by the other ear. Interaural attenuation is the reduction in sound energy of a signal as it is transmitted by bone conduction from one side of the head to the opposite ear. Interaural attenuation for air conduction can range between 40 and 80 dB. Masking should be used if the difference in air conduction in the test ear and bone conduction in the non-test ear is 40 dB or greater. The type and level of masking are noted on the form on which the test results are recorded.
Transducers: Bone vibrators are used for bone-conducted threshold measurements for frequencies within their respective frequency response ranges and must meet the specification of Mechanical Coupler for Measurement of Bone Vibrators (ANSI, 2002). Standard bone-conduction vibrator placement should allow mastoid or forehead placement with proper force applied (Dirks, 1964). The test ear should never be covered or occluded for standard bone-conduction measurements. The contralateral ear will be covered or occluded when masking is being used.
Frequency: Thresholds are measured at octave intervals from 250 to 4000 Hz and at 3000 Hz. When testing is performed for bone conduction at 250 Hz and 500 Hz and thresholds are obtained in the 35 and 55 dB HL range, there is a high probability that the responses were a result of tactile rather than auditory stimulation (Roeser, Valente, & Hosford-Dunn, 2007). Suspected vibrotactile responses are noted on the audiogram form. Higher frequencies may be tested if the transducer has sufficient frequency-response characteristics.
Order: The initial frequency used for testing should be 1000 Hz. After the initial test frequency, the audiologist should test at 2000, 3000, and 4000 Hz, followed by a retest at 1000 Hz before testing at 500 and 250 Hz.
Masking: Typically, if the unmasked bone-conduction threshold is 10 dB or greater than the air-conduction threshold at that frequency in either ear, masking is used. Because the threshold values on which the calibration of bone vibrators is based were measured with masking noise in the contralateral ear, the audiologist may prefer to always use masking in the testing procedure. The type and magnitude of the masking sound should be noted on the form on which the test results are recorded.
The chart below offers potential test modifications for issues encountered during pure tone audiometry. The modifications are not intended to be comprehensive in scope or ideal for all situations. Sound clinical judgment is always paramount.
|Developmental age of the patient||Age-appropriate test modifications, such as visual reinforcement audiometry, conditioned play, conditioned orientation response, or computerized audiometry, may be used.|
|Claustrophobia||Tell the patient how to exit the booth or test with the booth door ajar. If the door is left open, consider use of insert earphones to minimize effects of ambient noise.|
|Exaggerated or non-organic hearing loss||Consider reinstruction, counseling, and reexamination. In compensation cases, ascending threshold technique may be used.|
|Collapsed ear canal||Insert earphones, support the pinna from behind to prevent the collapse, or test with the participant's mouth open ( Reiter & Silman, 1993).|
|Tinnitus||Use pulsed signal or a warble tone to help distinguish the test signal from the tinnitus.|
|Physical limitations for motor response||Modify motor response task or use verbal response task.|
|Severe/profound hearing loss||Begin testing with low-frequency pure tones.|
|Difficult to test||Reinstruction, counseling, and reexamination are valid strategies. Use alternative objective measures (e.g., ABR). Modify behavioral procedures as appropriate to cognitive abilities. Repeat familiarization task at test frequencies other than 1000 Hz, when responses are inconsistent.|
Speech audiometry includes speech awareness/detection thresholds, speech recognition thresholds, word recognition testing, and sensitized speech testing (filtered, compressed, speech in noise, etc.) and is used to evaluate hearing sensitivity and speech perception ability and for site-of-lesion testing.
A speech threshold test quantifies an individual's hearing threshold level for speech. Agreement between the speech threshold and the PTA should be -/+7 dB. The option to substitute a Fletcher average (the two best frequencies) is appropriate when the hearing loss is sloping (>15 dB/octave) in configuration. Clinically, the primary purpose of a speech threshold test is to serve as a validity check for the pure tone audiogram.
Speech Recognition Threshold (SRT). The speech recognition threshold is the minimum hearing level for speech (ANSI, 2010) at which an individual can recognize 50% of the speech material. Speech recognition thresholds are achieved in each ear. The term speech recognition threshold is synonymous with speech reception threshold. Spondaic words are the usual and recommended test material for the speech recognition threshold. Other test materials can be used. If so, then the test material should be noted in recording and reporting the results.
Speech Detection Threshold (SDT)/Speech Awareness Threshold (SAT). The SDT/SAT is the minimum hearing level for speech at which an individual can just detect the presence of speech material 50% of the time. The listener does not have to identify the material as speech, but must indicate awareness of the presence of speech sounds. The material used to obtain a speech detection threshold should be noted in recording and reporting the results.
When circumstances or individual capabilities prevent determination of a speech recognition threshold (SRT), the speech detection threshold (SDT), sometimes referred to as speech awareness threshold, may be determined instead. The SDT will occur at a lower level than the SRT, because the SDT depends on audibility alone, whereas the SRT requires that a patient both hear and identify the speech signal. Threshold of detection can be expected to be approximately 5 to 10 dB better than threshold of recognition.
The type of speech material is not as critical for this measure, because it reflects detection and not recognition. Some common materials are speech babble, running speech, or familiar words. Nevertheless, specification of the type of material helps to ensure test-retest reliability and may be useful information for future hearing evaluations.
The usual response mode for obtaining the speech recognition threshold is repetition of the stimulus item. For patients for whom it is not possible to obtain verbal responses, alternative response modes are needed. Many alternatives are acceptable but must convey recognition of test items from a closed set of choices. For example, response modes can take the form of picture pointing, signing, or visual scanning. In addition, if a picture-pointing task is used for obtaining the speech recognition threshold, then the clinician should be cautious in choosing the number of response items. Too few items increase the probability of chance performance, and too many items may be distracting and increase response time (e.g., a number between 8 and 12 words is usually appropriate). The audiologist considers behavioral, cognitive, and language issues that may impact a patient's testing results.
For assessing the speech detection threshold, a number of response modes can be used to convey signal detection. Usually, these response modes are nonverbal. Whenever a response mode other than repetition of a spondaic word is used, it should be specified in recording and reporting the results.
The basic procedure for determining speech recognition thresholds consists of instructions, familiarization, a single series of descending threshold determinations, and calculation of threshold hearing level.
Either a recorded or a monitored live voice technique can be used to obtain the speech threshold. Recorded presentation of the test material is the preferred procedure. When monitored live voice is used, it should be noted with the test results.
Techniques for establishing an SRT include:
Technique A (after Downs & Minard, 1996)
Technique B (after Huff & Nerbonne, 1982)
Masking: When the obtained speech recognition threshold (or speech detection threshold) of one ear exceeds the apparent speech recognition threshold (or speech detection threshold) or a pure tone bone conduction threshold at either 500, 1000, 2000, or 4000 Hz in the contralateral ear by 40 dB or more, masking should be applied to the non-test ear. The appropriate masker for a speech stimulus must have a wideband spectrum (e.g., white noise or speech-spectrum noise). The level of effective masking used should be sufficient to eliminate reception by the non-test ear without causing overmasking and should be recorded on the same form as that used to record audiometric results.
Word recognition scores are obtained for each ear using phonetically balanced (PB) monosyllabic words and are expressed as a percent correct. There are several word lists available.
Testing may be terminated after 10 words, if no errors occur, or after 25 words, if there are no more than four errors. Otherwise, the full 50-item list is administered (Runge & Hosford-Dunn, 1985).
Masking: Masking is used for word recognition testing when the presentation level in the test ear exceeds the best bone conduction threshold in any of the speech frequencies for the non-test ear (500, 1000, and 2000 Hz) by 35 dB or more (Roeser et al., 2007).
Either a recorded or a monitored live voice technique can be used to obtain the word recognition score. Recorded presentation of the test material is the preferred procedure, as it standardizes the composition and presentation of the test list, allows for better control of the intensity of the test items, and ensures that the speech pattern of the recorded talker will be consistent for each client. When monitored live voice is used, it should be noted with the test results.
Specific considerations are given when evaluating the speech recognition skills of non-English and limited English proficient (LEP) speakers. Monolingual audiologists may not be able to appropriately administer and monitor tests developed in other languages, whether presented in live voice or pre-recorded. Reducing the test set size by including only familiar words may result in inaccurate threshold measurements. Alternative measures of speech recognition have been developed, such as using paired digits as stimuli. This measure has been found to accurately evaluate the hearing threshold for speech in non-native English speaking adults and to closely match the pure tone average (PTA) threshold. The services of a trained interpreter/translator may be needed to obtain the most accurate word recognition scores. However, it is not appropriate to simply translate English materials. Test materials must reflect the phonetic balance of the patient's language.
A number of self-assessments are available to measure the level of disability or handicap caused by the hearing loss in a patient's everyday life and provide an individualized assessment of specific situations that cause communication difficulty to the patient. Measuring the extent to which a hearing loss is limiting or restrictive provides the audiologist with additional information about the patient's communication needs and motivation and serves as an outcomes measure or as a baseline assessment against which to compare the eventual benefits gained from hearing aid amplification. See self-test for hearing loss.
Auditory brainstem response (ABR) testing is used mainly to diagnose hearing loss in difficult-to-test patients and for differential diagnosis of cochlear hearing loss versus retrocochlear hearing loss, specifically tumors of cranial nerve VIII. Auditory evoked potentials, originating from cranial nerve VIII and auditory brainstem structures, consist of five to seven identifiable peaks that represent neural function of the auditory pathways and nuclei. The ABR is a sensitive indicator of functional disorders of the VIIIth nerve and lower auditory brainstem and is often the first test of choice if a disorder is suspected.
The ABR component waves, especially Waves I, III, and V, are easily recordable in many cases and are very reliable in terms of their latency. Although absolute numbers will vary across clinics, the latencies are relatively stable across individuals. The I-V interpeak interval in most adults is approximately 4 msec, and the standard deviation of this interval is about 0.2 msec. Thus, 95% of the adult population have I-V interpeak intervals of 4.4 or less. If the I-V interval exceeds this amount, it can be considered abnormal (Stach, 2010).
Click stimuli at a high level (e.g., 80-90 dB nHL) is adequate in most situations to identify Waves I, III, and V. If no response is obtained at the maximum output level, the audiologist obtains one run of rarefaction clicks and one of condensation clicks to distinguish between cochlear and neural dysfunction. A catch trial (i.e., signal running but not delivered to the ear) can rule out a stimulus artifact that may be misinterpreted as the cochlear microphonic (CM).
Measurements that are used include
Note: Cochlear pathologies are typically associated with a delay of Wave I.
Measurements that are used include
When behavioral audiometric tests are judged to be unreliable (i.e., non-organic hearing loss), ear-specific thresholds cannot be obtained, or results are inconclusive regarding type, degree, or configuration of hearing levels, threshold testing-such as ABR, bone conduction, or ASSR-may be used as part of the assessment process to predict hearing thresholds.
Predicting hearing sensitivity using ABR involves determining the lowest intensity level at which an auditory evoked potential can be identified. Click or tone-burst stimuli are presented at an intensity level that evokes a response. The level is then lowered, and the response is tracked until an intensity is reached at which the response is no longer observable. This level corresponds closely to behavioral threshold.
Stimuli: Frequency-specific stimuli are tone bursts of low, mid, and high frequencies.
Transducer: A complete audiologic evaluation includes both an air-conduction and bone-conduction ABR, when indicated. Insert earphones are recommended, unless contraindicated, for air-conduction testing.
Bone-conduction thresholds are established in a manner similar to air-conduction thresholds, but with a different transducer. A bone vibrator is used to generate vibrations of the skull and stimulate the cochlea directly. In theory, thresholds by bone conduction reflect function of the cochlea, regardless of the status of the outer or middle ears.
Note: Responses are typically attempted down to 20 dB nHL in at least 10 dB steps.
The auditory steady-state response (ASSR) is an auditory evoked potential, elicited with modulated tones that can be used to predict hearing sensitivity in patients of all ages (Dimitrijevic et al., 2002; Rance & Rickards, 2002). The response itself is an evoked neurological potential that follows the envelope of a complex stimulus. It is evoked by the periodic modulation of a tone. The neural response is a brain potential that closely follows the time course of the modulation. The response can be detected objectively at intensity levels close to behavioral thresholds. The ASSR can yield a clinically acceptable, frequency-specific prediction of behavioral thresholds.
Stimuli: Frequency-specific stimuli are amplitude- and frequency-modulated pure tones with typical carrier frequencies of 500, 1000, 2000, and 4000 Hz.
Transducer: Insert earphones are recommended, unless contraindicated, for air-conduction testing. A bone-conduction transducer will be needed if air conduction is elevated (i.e., if air-conduction thresholds are greater than 20 dB nHL, bone-conduction testing is completed to assess the type of hearing loss).
Note: ASSR analysis is mathematically based. The specific method of analysis to define threshold is dependent on the manufacturer's statistical detection algorithm.
It is essential that all audiometric equipment be calibrated, be functioning properly, and be used in an acceptable test environment to ensure accurate test results as specified in American National Standards Institute/Acoustical Society of American (ANSI/ASA) Standard s3.6-2010.
Equipment and transducers are to meet applicable specifications of ANSI/ASA S3.6-2010 (ANSI, 2010), ANSI S3.39-1987 (ANSI, 1987), and manufacturer specifications and be appropriate to the test technique being used. In addition, exhaustive electroacoustic calibrations are to be performed annually using instrumentation traceable to the National Institute of Standards and Technology; functional inspection, performance checks, and bioacoustic checks are conducted daily to verify equipment performance prior to use (ANSI, 2010).
Test environments should meet the specifications detailed in Maximum Permissible Ambient Noise Levels for Audiometric Test Rooms (ANSI, 2003). In addition,
Confirmation of an acceptable test environment should be documented at least annually.
Adherence to universal precautions and appropriate infection control procedures should be in place. Instrumentation coming into physical contact with the patient must be cleaned and disinfected after each use. Disposable acoustically transparent earphone covers or disposable insert earphone tips are recommended, and clinician hand washing between patients should be routine (Siegel, Rhinehard, Jackson, Chiarello, & the Healthcare Infection Control Practices Advisory Committee, 2007). See OSHA standards relating to occupational exposure to bloodborne pathogens and the Centers for Disease Control and Prevention's universal precautions for preventing transmission of bloodborne infections.
Service provision for patients with hearing loss begins soon after the diagnosis is made and comprises audiologic rehabilitation, including the selection, fitting, and evaluation of technology (if amplification is selected as a treatment approach). When selecting any treatment approach, the audiologist considers and incorporates the individual's and his/her family's goals, preferences, values, beliefs, and cultural and linguistic background.
Treatment approaches include
Individual Practice Portal pages on amplification, cochlear implants, audiologic rehabilitation, and aural rehabilitation are being developed; links will be provided in the future.
Hearing assistive technologies systems (HATS) include a large variety of devices designed to improve audibility in specific listening situations. HATS may be designed for use with hearing aids or cochlear implants or to be used alone and may be intended for personal use or group use. See classroom acoustics.
The American Academy of Audiology Task Force (2011) suggests several steps for the provision of HATS. While the guidelines are specific to remote microphone HATS for children, these steps may also be relevant to adults and to other forms of HATS. They include:
Examples of HATs include
Frequency Modulation (FM) Systems—radio waves are used to transmit sound from the source to a receiver worn by a person. FM systems are often used in large settings (e.g., classrooms, restaurants, nursing homes, theaters, places of worship, museums).
Infrared Systems—sounds are converted into infrared waves then back to sounds by the listener's infrared receiver. These systems are often used in the home with television sets, but can also be used in large settings, such as theaters or classrooms.
Induction Loop Systems—hard-wire loops are placed under floors or around walls, and sounds are converted to magnetic forces. Cochlear implants and hearings aids with telephone switches or t-coils pick up these forces and convert them to sounds.
Telephone Amplifiers—speech heard over the phone is amplified. Telephone amplifiers are useful for people who don't wear hearing aids.
Voice Carryover Telephones (VCO)—VCO telephones connect a person with hearing loss to a local relay service.
Text Telephones (TTD or TTY)—this telephone works like a typewriter and sends and receives typed messages through telephone lines.
Alerting Devices—devices that provide a signal in response to sound may use strobe lights, regular lights, or vibrating systems to alert a person with a hearing loss that a sound has occurred. Examples include
Personal Amplification Systems—systems such as streamers (Bluetooth), mini remote microphones, and apps are designed for individuals with hearing loss.
HATS system selection considerations include
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Content for ASHA’s Practice Portal is developed through a comprehensive process that includes multiple rounds of subject matter expert input and review. ASHA extends its gratitude to the following subject matter experts who were involved in the development of the Hearing Loss: Ages 5+ page:
The recommended citation for this Practice Portal page is:
American Speech-Language-Hearing Association (n.d.). Hearing Loss: Ages 5+ (Practice Portal). Retrieved month, day, year, from /Practice-Portal/Clinical-Topics/Hearing-Loss/