Idealism Versus Reality: What’s Your Preferred Hearing Screening Procedure?

You’ve been invited to offer hearing screenings at an important community-wide gathering, and you see this as a prime opportunity to spread the word about hearing awareness and provide your city’s people with a knowledge about their own level of hearing health. You’re to be applauded for accepting this task. But what kind of standards can you set—or even be expected to set—in your hearing screening efforts?

Hearing screening seems to be an easy and simple procedure that is administered by many professionals in different fields and, when compared with puretone audiometry or complete audiologic evaluations, is given perfunctory treatment in the literature.

Many excellent textbooks devote several chapters on various diagnostic methods, such as puretone audiometry, but few offer even a short discussion regarding puretone hearing screening procedures.^1-6 For the existing print resources, as well as the various state hearing screening programs describing puretone hearing screening, the focus is mainly on the overall structure of the screening program, including sensitivity, specificity, cost-effectiveness, and the frequency and presentation level of the signals for the screening,^1-12 rather than on the details of the rationales, precautions, and considerations for the screening, as well as the practical screening procedures that, clinically speaking, are more worthy of our attention.^1-12

In the field, there are varieties of professionals, other than audiologists and hearing instrument specialists, who administer hearing screening for the public. These include speech language pathologists, nursing practitioners, physicians’ assistants, graduate clinicians in communication sciences and disorders, certified state health-related professionals, volunteers, etc. Additionally, the sites where the actual hearing screenings are performed vary dramatically from a standard sound-treated hearing testing booth, to a seemingly “quiet enough” corner in a room where a health fair is being held, to disconcertingly noisy venues inside convention halls or at sporting events. Further, the people seeking and receiving the hearing screening services also differ in terms of their possible pathologies in ear-brain system, actual hearing sensitivity, age, personality, past experiences with hearing screening, and their expectation and purpose of receiving the screening.

Different health care professionals who administer hearing screening obviously receive different levels of training from various programs. Likewise, the target audience plays a key role in screening strategy. For example, the way to handle a hearing screening for a group of 3- to 6-year-olds may be radically different from that for a group of college students or for seniors. Providing hearing screenings at a standard hearing testing booth in which ambient noise levels are under control is, of course, more valid and reliable compared to a site where door prizes are announced and other loud events are being offered within an overcrowded exhibit hall.

Apparently, the rationale, handling techniques, and precautions of the implementation of hearing screening would and should be different according to these different client populations of various age ranges and pathologies at different sites. In short, the practical issues of implementing hearing screening may not be as easy and simple as many might think.

As an instructor, I’m often in a quandary on how we teach future audiologists and speech language pathologists to perform hearing screening for the public so that valid and reliable data are obtained. In the real world, a result of “fail” from a hearing screening should not be viewed simply as a statistic, especially for young children or even college students, since that failure could become a burdensome worry for the involved teachers, counselors, and the parents who must then try to figure out what it means and where the financial resources are for the thorough audiologic evaluation.

Therefore, a practical question is, in order to have a valid “hit rate” and fewer false-positives, what is the appropriate and preferred procedure for hearing screening in the real world? And why? The following deliberations are related to the most frequently mentioned type of hearing screening: puretone air conduction screening via headphones.

1) Which Ear First and Why?

This seems to be a good, but also trivial, question. For puretone audiometry, it is usually recommended to test the better ear first. This is mainly for convenience and time-saving purposes, since it is easier to adjust the audiometer’s settings for masking, if needed, after obtaining the better and worse ear’s thresholds. Because little on this subject relative to screening is offered in the literature, it seems logical to follow the lead of puretone audiometry by screening the better ear first—if the individual knows which ear is better.

When providing hearing screening for the masses, the clinician may not have time to check verbally with individuals about the better/worse ear, and simply screen the right ear of the person first. This may also be a good strategy since the majority of the individuals are right-handed and their right ear is assumed to be the better ear in hearing.

However, if one knows in advance that one ear is better than the other, screening the better ear first may still be a good reference point since the listening/responding of the better ear to the puretone signals may help that person to settle down quickly, increase their alertness to the signals, increase the validity/reliability of the screening results, and serve as a baseline when screening is performed on the other ear.

In the end, screening the right or left ear first does not make a real difference, and one may go ahead and screen the right ear first for the majority of the populations during the hearing screenings.

2) Appropriate Instructions and Required Response

Clinical experience shows that the instruction given to individuals during hearing screening could be the same as that used for puretone audiometry. Practically, however, the instructions used by various clinicians differ substantially.

The first level of instruction should be as short and simple as possible to avoid any possible confusion. One sample of instruction is “Just press the button (or raise your hand) whenever and as soon as you hear the signal.” Most of the time, individuals understand this simple instruction and ready themselves for the listening task. If individuals have questions about the instruction, they’ll usually ask “Which ear?” or “What signal?” In this case, further details of the instructions are provided like “One ear at a time, and your right ear first,” or “The signal is any signal or any sound from the earphone.” Based on clinical experience, provision of simple, short, but complete instruction is effective for even the majority of people with no prior experience in hearing screening or hearing evaluation.

For very young children or people with special challenges (eg, mental retardation, neurological disorders, etc) with whom verbal instruction seems to be less efficient and smooth, the instruction can be conveyed by using gestures, body language, and simple demonstration. In fact, for hearing screening and puretone audiometry, verbal instruction is not always needed; instead, a physical demonstration to show “Press the button (or raise your hand) whenever you hear the signal” works well, especially for young populations and hard-to-test clients.

Right/left hand raising. The required patient response for the screening/listening task is usually pressing a button or raising a hand. For the hand-raising, young children might have a tendency, or quite often might have been instructed before by some clinicians/screeners, to raise their right hand when hearing a signal from the right ear and their left hand when hearing a signal from the left ear. As a matter of fact, this kind of response is not theoretically and clinically accurate for both puretone audiometry and hearing screening. This is because asking subjects to listen and make lateralization judgments relative to where the signal originates (right or left ear) requires more sound energy than simply asking them to perceive the presence of the signal. Thus, it is a kind of listening/discrimination task other than perceiving the presence of the signal, which is more appropriate to the purpose of hearing screening or even hearing threshold testing.

Therefore, the right/left ear discrimination should not be a part of the testing. By allowing this kind of response, young children might turn out to be giving hand-raising responses in an alternative manner—raising their right hand and then left hand—regardless of the ear in which the signal is actually presented. This has the potential to increase the false-positive rate, reduce the validity and reliability of the testing findings, and pose unnecessary challenges to the clinician’s clinical decision-making process simply because of the confusion induced in the clinician’s mind about the required responses.

So, how do you accomplish re-instruction if young clients display alternative hand-raising responses? The solution is through the physical demonstration again; conditioning and demonstrating to the individual several times by simply lifting up their right hand while holding down their left hand, or vice versa for left-handed individuals, after imitating a signal they can hear.

A clear definition for the required and permissible hand-raising response is critical for routine hearing screening procedures.

3) Which Frequencies and How Do You Test for Them?

There are many guidelines, suggestions, and federal and local regulations in terms of the frequencies used in hearing screening. For example, one guideline suggests not including 500 Hz and screening only at the three frequencies of 1000, 2000, and 4000 Hz because of considerations regarding pass/fail rates.¹¹ Another recommends the addition of 500 Hz for low frequency pathologies.¹⁰ Some recommend the inclusion of 6000 Hz for noise-induced hearing loss,¹² and many enforce various combinations of screening frequencies.^9,12

So, this is a question with many different answers based on different guidelines or state hearing screening instructions/manuals. However, following the lead of puretone audiometry, one could carry out the hearing screening for the right ear at 1000, 2000, 4000, and 8000 Hz, and double-check 1000 Hz, then test at 500 and 250 Hz. You could then perform the same procedure for the left/worse ear if the screening is administered in a standard sound-treated testing booth. Including these six frequencies is a thorough procedure and may identify conductive problems (middle-ear infections and others) at the two lower frequencies (500 and 250 Hz). The screening may also be able to identify sensorineural problems (noise-induced hearing loss, age-induced hearing loss, drug-induced hearing loss, etc) at the higher frequencies (4000 and 8000 Hz).

When providing hearing screening services for some institutions or schools that ask for screening at only three or four frequencies, clinicians may do the screening at those frequencies as requested. They should also pay attention based on their suspicions and include other frequencies, if needed, for identifying those who may benefit from further complete audiologic evaluation.

More on the lower thresholds. Puretone hearing threshold testing usually does not include 125 Hz, and thus it is rarely mentioned in hearing screenings. The reason for this is that testing at 125 Hz takes lots of electric energy for our ear-brain system to hear the signal, and lots of distortion is associated with the signal, negatively influencing test reliability. Also the conductive component of pathologies can usually be identified by the testing at 250 Hz and probably 500 Hz. Meanwhile, it is rare to test or screen at 1/3-octave frequencies such as 3000, 6000, or 750 Hz, unless deemed necessary.

Implementing hearing screening at the six frequencies as suggested above is the most thorough procedure. When performing the screening in a sound-treated testing booth, one could screen at the six frequencies including the 250 Hz. When carrying out the screening outside the sound-treated booth, such as in a regular classroom or office without having the ambient noises under control, one may consider doing the screening for only five frequencies (ie, including 500 Hz but excluding 250 Hz).

In a non-sound-treated testing suite, it is known that testing at even 500 Hz will be associated with poorer reliability such that many normal-hearing individuals may still fail at the lower frequency, possibly resulting in over-referral. Thus, when deciding to include 250 Hz, precautions need to be taken. These may include the instructions given to the individual (eg, respond to any signal coming from the headphone without regard of which ear hears the signal), headphone placement (the earphone should be aligned with the external ear canal opening with the headband in the “front” of the skull and the length of the headband fully “shortened” down to reach a snug fit around the skull), amount of environmental noise (no low-frequency noises or vibrations that could easily result in false-fail at 250 or 500 Hz), new graduate students who do not have much experience (newcomers may make all kinds of mistakes leading to false-fail and false-pass), to name a few.

4) Starting Frequencies and Sequences

For puretone audiometry, most textbooks recommended starting threshold testing with 1000 Hz first, then testing the higher frequencies second, and finally moving to testing the lower frequencies. For hearing screening, one should also determine these details for the procedures with practical rationales.

There is actually no fixed sequence for the frequencies to be tested, but clinicians do need “your own” procedures with “your own” rationale. Most textbooks suggest using and testing 1000 Hz first because it is a frequency that individuals are familiar with and provides reliable data for the testing. In reality, one can actually start the testing/screening at any of the frequencies mentioned above and then move to either the higher or lower frequencies.

The No. 1 clinical principle of testing and screening is to gather the most valid and reliable data within the least amount of time. For example, when screening a group of children that includes children with runny noses and known histories of recurrent otitis media (ie, higher chance of conductive problems), one can screen for lower frequencies first to get valid and reliable data while the youngsters are still energetic and concentrating on listening for those faint signals. Similarly, when screening a large geriatric group with many people patiently standing in line, one can screen for the higher frequencies first, saving time and gathering valid data in the least amount of time. So again, clinicians need to hone their own hearing screening procedures for the appropriate situations, and they need to know why that procedure was carried out that way on that date.

5) Screening Criterion: What’s So Magical About 20 to 25 dBHL?

The criterion of 25 or 20 dBHL is widely used for the majority of the clients being screened.^7-12 Once again, there is no fixed criterion to be used in the real world. It could be 10 dBHL for the high-risk young children when the purpose of screening is to rule out conductive hearing losses associated with recurrent otitis media. It could be 45 or 55 dBHL when the purpose is to rule out sensorineural hearing loss from an elderly group of subjects, or when the environmental noise level at the screening site is very high. But, in all of these cases, the criterion used does need to be written down on the screening record for later consideration.

6) Is a Familiarization Procedure Really Necessary?

Familiarization is widely used in the threshold determination process during puretone audiometry. That is, after deciding to test at a certain frequency first, for example 1000 Hz, the clinician starts the 1000 Hz signal at a level assumed to be neither too soft to be unheard nor too loud such that it would startle the person tested. The idea is to start testing by using higher signal levels to ensure that the client hears it and responds appropriately. Once ascertained, the signal level is systematically lowered by 10 dB each time until reaching the no-response level from the client—a soft level that is close to the subject’s threshold hearing level.

After this familiarization procedure, the down-10-up-5 dB procedure for threshold determination is followed. The purpose of this is to familiarize the subjects in recognizing what the signals sound like and fine-tune their perception and alertness level down to those soft signal levels that are barely perceptible. Because this requires critical listening to faint signals in background noise—including the individual’s own breathing, heartbeat, and possible mental distractions—it involves a higher level of concentration and alertness. Thus, the familiarization procedure has been viewed as clinically imperative for the validity and reliability of data collection.

For the hearing screening, one may follow the same lead by starting the signal of the first frequency (eg, 1000 Hz) at a higher level (65 or 75 dBHL) and then lowering it by 10 dB each time to see if the person tested continues to respond down to 25 dBHL (or the criterion level used that day). Familiarization is cognitively and empirically important and necessary for shaping and sharpening a person’s alertness to the soft signal level, which is again closely related to the pass/fail rate of the entire hearing screening. In addition, the concept of probability of looking for two out of three good/reliable responses to verify/increase the accuracy of a pass/fail judgment at each frequency is definitely a “must” to be implemented.

7) Patient Records of the Hearing Screening

Most clinicians providing hearing screening services offer a hearing screening slip/form for the client to keep as a record of their screening results—either passing or failing the screening for the right or left ear specifically. This form usually contains simple identification information on the individual being screened, the ID information of the facility, the signature/date line for the clinician and supervisor who provide the screening services, and an area that shows whether the individual passed or failed the hearing screening.

Actually, this screening slip/form could be designed to be more versatile and complete for multi-usages. For example, it should list the criterion (in dBHL) used for screenings that day, a simple check-mark area showing the type of screening/testing site (eg, testing booth, an office, or description of the testing environment), another check area showing the frequencies screened, and an area that denotes which frequencies the person failed the hearing screening in right and/or left ears. All of this information would be extremely useful as background information for a case history in the event the individual seeks referral for complete audiologic evaluation.

8) Interpretation of Results

Interpretation of the screening results may be viewed as an easy subject, but it is actually a challenging area that might go beyond the scope of training of the screening providers. Although the results of a hearing screening are either a pass or fail, interpretations should rely on in-depth knowledge in various hearing disorders and clinical/audiologic experiences. Obviously, the level of interpretation offered by the service providers would not be the same depending on whether the screening is provided by, for example, an audiologist, speech language pathologist, nursing clinician, physician assistant, graduate clinician, etc. The basic and fundamental information for the findings, however, should be explained to the person tested without going beyond the scope of practice of the tester.

A “pass” can usually be noted to the individual as “You have passed the hearing screening at [this dBHL level] in your right/ left/both ears.” The “pass” could be viewed as: this individual should have normal hearing sensitivity at the frequencies screened at the criterion level in dB used. This means that the individual also might be with hearing problems that have not been found from the screening but is overall most likely to have normal hearing sensitivity. If the individual still intends to receive further evaluation because of certain suspicions, or is already with some signs or symptoms of disease, then, of course, further audiologic evaluations are warranted and should be encouraged—even if a “pass” result is issued on the hearing screening.

When the screening result is “fail,” the interpretations should be carried out with equal or more caution. The “fail” at a hearing screening basically points out that the individual should seek further audiologic evaluation. It also could be associated with an individual with normal hearing sensitivity who simply failed to respond to the task appropriately due to nonauditory factors, several of which have been discussed previously.

The important and acceptable-to-client concepts are that a “pass” does not necessarily mean normal hearing sensitivity, while a “fail” does not necessarily equal hearing loss or pathology. The only and best way to find out the answers is to refer the individuals for complete audiologic evaluation (ie, a 1-hour versus a 3-minute screening) to reach a thorough diagnosis.

The knack of implementing these interpretations is to let the public know that the pass/fail finding is a gross screening result that needs to be further verified, especially when concerns about the finding exist. In brief, a pass/fail could be a true “hit” in findings, but could also be a false-pass or false-fail related to many factors, such as the training and experiences received by the service providers, instructions used, procedures carried out, criterion in dB and frequencies screened, the audiometers used, the room acoustics in the testing site, client-related variables, etc.

9) What About Cross-contamination?

Cross-contamination is a clinically important but frequently neglected area of the hearing screening. Many practitioners just provided hearing screenings for the public without having any infection control procedures in mind.

However, when the hearing screening is provided, it is the responsibility of the clinician to see that prevention of possible cross-contamination is observed. While it is impossible to know the health status of those being screened, two examples of high-risk subjects might be young children suffering from otitis externa or otitis media and adults who carry certain skin diseases with suspiciously infectious liquid/secretion noticeable on their face/ear regions.

The best way to deal with this is to keep the infection control materials, such as earphone covers, audiowipes, and other hospital-grade sterilization/disinfection materials, at hand all the time whenever a hearing screening event is held—and use them after each person is tested. Earphone covers can protect the earphone cushion without substantial reduction of the signal level being delivered to the ear, while the chance for the infectious liquid/agent to cross over to the earphone cushion is largely reduced. Audiowipes, or other wet paper towels with disinfection materials, can be used to wipe clean the earphone, client handheld response switch, and the contact surface of the desk/chair top area in between the screening/testing of individuals.

This simple procedure is a good safeguard against the chances of passing possible infectious agents from some clients who might actually have middle ear infection to the next individual who is healthy—or possible contamination from the person tested to the clinician (and vice versa).

10) Other Important Considerations

As with puretone audiometry, certain technical considerations and precautions should also be applied in hearing screening procedures. These may include the use of different signals, duration of each signal presentation, time pattern of signal presentation, release of visual clues of signal presentation, and clinical decision-making for false-positive, false-negative, and unusual client response features.

Different signals. The three kinds of signals—puretone, warbled (FM) tone, and paused tone—usually useful for puretone audiometry could also be freely used for hearing screening procedures. The puretone is good for generating valid and reliable data for the majority of the public. When screening pediatric populations, the FM signal or paused tone may give higher chances for raising their interest/curiosity during the screening process and thus lead to more complete screenings. For elderly people or for those with tinnitus, the warbled tone could be the stimulus choice, as it may be easier for them to differentiate the testing signal (warbled tones) from the ringing in the ears (usually high-pitch tone-like sounds in their cognition).

Duration and time pattern of signal presentation. The duration of each signal presentation is frequently an area in which a new clinician makes mistakes by delivering the signal with a shorter-than-necessary duration, leading to higher false-fail rates. The basic concept is that each signal (puretone, FM signal, or paused tone) should be presented for 1 to 2 seconds for the ear-brain system to actually have a chance to recognize and respond to it.

Presenting signals in a rhythmic time pattern is another frequent mistake. When a clinician becomes familiar with and skillful in screening/testing procedures, it is natural to fall into a fixed rhythm when turning the dial to the intended signal level and pressing the button for signal presentation. This kind of rhythm is something that subjects can condition themselves to, anticipating the next signal presentation. Consequently, the person tested responds intermittently and frequently to the “anticipated” signals even while being unable to hear the signals. This kind of false-positive response can lead to incorrect clinical decisions and inaccurate pass/fails.

Visual clues during signal presentation. Another factor related to a high false-pass rate is the clinician’s broadcasting of visual clues during signal presentation. Each time a puretone signal is being presented, especially by a newcomer or inexperienced clinician, some visual clues may also be sent unintentionally, such as the clinician’s finger movement, upper arm or shoulder movement, head/eye lifting to look for client response, or even subtle movements like eyelid/eyebrow lifting that the test taker can quickly associate with signal presentation.

Everyone from curious kids to sophisticated adults can detect these visual clues’ timely relationship with the puretone signal and respond accordingly. This has the potential to transform the hearing screening into a kind of visual test. Thus, all clinicians should train themselves in removing all of the visual cues from their facial expression and body language and be able to maintain a poker face when administering the hearing screening. Clinically, this poker face is critical and requires constant self-practice and self-control.

Client’s seating position. Some clinicians frequently have clients seated with their back facing the clinician for the hearing screening process because, with this seating position, the individual is unable to see the clinician’s movements, facial expressions, and body language. However, this back-facing-clinician position is not ideal since the clinician cannot observe some subtle, but meaningful, facial expressions of the individual, such as the person’s confidence in raising his/her hand or pressing the button. The experienced clinician gains insights when viewing the subtle movements and facial expressions of clients, and this supplements the clinical decision-making process when judging the validity of clients’ responses and alertness levels.

One practical approach is to have the client face the clinician at about a 45° angle during the hearing screening process. In this arrangement, the person tested may not be able to see the facial expressions and body movements of the clinician, yet the clinician may be given clues to help with judgments about the validity and reliability of responses during the screening.

Was that a response? Sometimes individuals may press the response button immediately after hearing the signal, and then continue to hold the button down. Similarly, when hand-raising is the required response, people (especially children) may raise their hand slowly for a few seconds after hearing the signal and keep their hand upright for several seconds, or they may lower their hand haltingly over an extended period of time. This kind of movement may cloud a response relative to whether a signal’s presence is perceived.

The solution is not to let the screening/testing be under the control of the person tested (ie, not allowing the slow responses to continue). Usually a simple re-instruction—via either a demonstration or verbal mode—that requests an immediate response to the signal will suffice to reshape/modify their responses. In brief, the slow response from clients is not the required one and needs to be reshaped into a quick response format for the most important principle in hearing screening procedures—obtaining valid and reliable data within the least amount of time.

Conclusions

Professionals in different fields should be aware that, in reality, many different puretone hearing screening procedures with solid rationales exist, but all these procedures need to be carried out with appropriate considerations and precautions. When administering the screening at different sites for different clients or client populations, you must modify and conform your own “preferred” hearing screening procedure for the most crucial objective: obtaining the most valid and reliable data with the lowest possible false-pass and false-fail rates for the given situation/environment in an efficient and timely manner. In the end, a central goal is being compliant with critical screening guidelines while also being innovative in realistic hearing screening procedures. Finally, a question that can and should always be asked of ourselves as clinicians is “What’s your preferred hearing screening procedure in reality and why?”

References

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Correspondence can be addressed to HR at [email protected] or Bailey Wang, PhD, at .