Hearing test method for children aged 6 months to 2 years
1.Sound localization response test
As the child grows older, the acoustic localization ability gradually develops and matures. At 6 months of age, the acoustic localization ability is well developed, with clear localization movements, and at 8 months of age, the vertical localization ability begins, first to the bottom and then to the top. The test method is still the same as the above-mentioned distraction test, but in addition to the horizontal sound source, the vertical sound source is also measured. The sound localization test is a valuable method for assessing hearing sensitivity in children aged 6 months to 2 years.
2.Conditioned directional reflex audiometry
The conditioned reflex audiometry is a behavioral test with additional reinforcement of the conditioned stimulus, that is, each behavioral response caused by the auditory stimulus is combined with a reinforcement condition, in order to increase the interest of the child in the response to the acoustic stimulus and maintain the persistence of the response, because at this age children tend to lose interest in the pure acoustic stimulus and thus no longer respond, so the test method is to enhance the response caused by the acoustic stimulus and maintain a constant The test is designed to increase the sensitivity and accuracy of the test. The common method for visual reinforcement audiometry, that is, the application of visual stimuli to strengthen the response to acoustic stimuli, acoustic stimuli given by the speaker, the child sitting on the mother’s lap, facing between the two speakers, 80 cm from the speaker, the speaker can be placed on the light or activity of the toy (in the child’s peripheral vision) at the beginning, while giving sound and light stimuli, such as the child has a response, after several conditioning training, changed to first give acoustic stimuli The purpose is to reinforce the head-turning or orienting response to the acoustic stimulus by visual stimulation. The test can be started by estimating the intensity of 30-40 dBSPL on the child’s auditory threshold, and by gradually decreasing the intensity of the acoustic stimulus, the child’s “minimum response level” can be assessed, and the acoustic stimulus signal is preferably a warble or narrowband noise. Schneider et al. used half-octave or 1-octave 200-1000 Hz narrowband noise as the acoustic signal for testing. The results showed that infants’ responses to low-frequency sounds differed significantly from those of adults, while high frequencies were consistent.
Behavioral audiometry in children aged 3-6 years
Behavioral audiometry of children over 3 years of age has the potential to make them respond to simple actions each time they hear a sound, i.e., the child actively participates in the test, which is different from the test method of observing reflex responses in small infants under 2 years of age, and acoustic stimuli can be given through headphones, and more accurate thresholds can be derived for both ears separately.
(I) Operant conditioned reflex method
This method is designed to keep the test subject interested and persistent in responding to stimuli in a specific situation by providing a reward if the subject responds to the stimulus.
1. Rewarded reinforcement operant conditioning audiometry: When the subject responds appropriately to the stimulus, he/she can receive a food reward. When the child is sitting at the table, there is a manual switch on the table, and the child is encouraged to press the switch when he/she hears the sound, and if the response is correct, a small piece of candy will fall out of the box. Acoustic stimulation can be done with 500, 1000, 2000 and 4000 Hz twittering sounds, with intensity starting from the estimated suprathreshold intensity of the child’s hearing, or with 500 Hz 90 dBHL, and then gradually decreasing the intensity until reaching the threshold, care should be taken that the sound given should not be rhythmic to avoid false positive responses.
2, visual reinforcement operant conditioning audiometry: for reinforcement with visual stimuli, such as the appearance of images on the screen instead of food rewards.
(B) Game audiometry
Game audiometry is to teach the child to complete an action after hearing a sound, so as to test the child’s hearing sensitivity. The examiner can choose a suitable for the development of the child’s motor system and the response behavior that the child finds interesting, this method is often the most reliable method to obtain the hearing threshold for infants and children over 2.5 years old, can be carried out through the sound field or headphones, can be designed according to this principle of a variety of test methods, the classical method are classical and matching box method.
1, classical type play audiometry. The method is the use of pure tone audiometer, to the test child wearing headphones, in front of the test child placed a string of beads or set of ring toys, or set a plate of plastic balls, and asked the child in each time after hearing the sound, that is, pull a string of beads, or set on a ring, or pick out a small ball, in order to maintain the interest of children should pay attention to give more different colors of the ball, beads, or ring, etc.. In addition, the test time should not be too long, available 500Hz and 2000Hz, gas, bone conduction method to give sound, often can obtain very valuable hearing information, or if necessary, add high frequency 4000, 8000Hz test.
2, the matching box test method. Application of pure tone audiometer and a special view box, box with a signal light, viewing window, box lighting switch, this switch can also be controlled by the tester at the same time. When the test, let the child wear headphones, sitting in front of the box, when the sound signal issued 1-2 seconds, the signal light on the box, then teach the child to press the box lighting switch, the test child can see the box through the viewing window of the active toy scene. After 1 or 2 times of training, change to only give sound, and the signal light on the box is not lit, observe whether the child will try to observe the scene inside the box and have to press the box lighting switch response. Repeatedly and continuously, and gradually reduce the intensity of the sound signal to the response threshold, so that we can understand the child’s hearing ability. If the child is not in accordance with the sound requirements and arbitrarily press the lighting switch, the examiner does not connect the line, so that the child can not observe the scene inside the box.
(C) pure tone audiometer test
The pure tone audiometer test provides detailed information about the hearing threshold of each test audio and makes a preliminary diagnosis of the nature of deafness, but requires the active cooperation of the subject to obtain reliable results.
Before the test, you should establish a relationship with the child so that he or she can eliminate fear, put on the headphones, and explain to him or her patiently. When hearing the presence of sound quickly raise the hand, when the sound disappears, quickly put down the hand, the test using the drop method. The child should be trained several times before the test officially begins until he or she understands. Because children often can not tolerate a long time test, so the test frequency can be reduced, such as only 500-4000Hz 4 octave tone, and increase the intensity of the change in the interval; can also be divided in 3 or 4 times to complete the test. During the test, the child’s cooperation and correct response should be praised and encouraged from time to time, in order to maintain the child’s enthusiasm for the response, especially for children aged 5 or 6 years old, who can obtain accurate air and bone conduction hearing curves through patient testing.
Objective hearing function test
Objective assessment of hearing function status by observing the physiological changes induced by acoustic stimulation is extremely valuable for pediatric hearing assessment because it does not require a subjective response from the subject. Traditional objective tests have been used to assess auditory responses in the form of monitoring electrical skin responses or changes in respiratory and cardiac rhythms, but they are not reliable and have little practical value. In the past two or three decades, objective auditory function tests such as auditory evoked potentials, acoustic conductance resistance, and otoacoustic emissions have been developed and are commonly used in pediatric hearing assessment.
(A) Auditory brainstem response (ABR)
Since the 1970s, auditory evoked potential test has been widely used in clinical practice as an objective auditory function test for newborns and uncooperative children, with short latency auditory brainstem response being the most common. This test is completely noninvasive to the subject, easy to record, and can be performed under sleep anesthesia due to the application of surface electrodes. Therefore, it is suitable for further evaluation of children from newborns to infants of all ages, including at-risk children, or children who fail behavioral screening, and children with developmental hearing and speech disorders.
(ii) Otoacoustic emission (OAE)
Otoacoustic emission is the only test, other than cochlear electrogram, that can objectively measure cochlear function. It can be divided into two categories: spontaneous and evoked otoacoustic emissions. Spontaneous otoacoustic emissions (SOAE) can be recorded in about 50-60% of normal pediatric patients, and its frequency range is wider than that of adults in the high-frequency part, ranging from 250-5000 Hz, and its amplitude is also larger than that of adults. TEOAE, SFOAE and DPOAE are mainly used in clinical applications in pediatric testing. TEOAE is a group of wave peaks that appear 5-15ms after a short acoustic stimulus, with an intensity of no more than 20dB, and a frequency distribution of 500-5000Hz. -5000Hz, with 1000-3000Hz as the main frequency distribution.
(C) Acoustic conductance resistance test
It is an objective test to observe the functional status of the auditory system through biophysical changes in the middle ear sound-transmitting structures caused by acoustic stimulation, and has been commonly used in clinical practice since the 1970’s. It is suitable for testing infants and children and can be used as a screening test because it does not require a subjective response from the subject and is simple and rapid to perform.
Pediatric speech testing
As hearing is the main source of information during language formation and plays a role in feedback adjustment of speech activities, studies have confirmed that infants and young children not only receive acoustic signals passively, but also show the ability to receive them actively. Infants with normal development have been shown to recognize or discriminate speech and sound changes at least by 6 months of age. For example, infants growing up in different linguistic environments have differentiated tones at 6 months of age. Therefore, it is believed that infants are born with the ability to perceive clues to the intrinsic characteristics of language, so that in the first year of life, depending on their language environment, they can further cognitively learn and correctly grasp the phonological patterns of language.
Speech testing of children is limited by many factors, such as age, immature speech development, poor comprehension, and even the presence of speech disorders, which make it impossible to use the method of recitation test vocabulary for children, especially hearing-impaired children, whose speech development lags behind that of normal children, and there is no standardized basis for test methods and judgment criteria. The main purpose of speech listening test for children is to estimate their speech sensitivity by applying reinforcement conditions to speech signals or by naming familiar objects and reducing the signal intensity according to the response.
(a) The same rhyming word picture piece test will be grouped by the same rhyming monosyllabic words (words), each group of 4, with the same rhyme, but different vowels (e.g., tiger, pig, mouse, rabbit; flower, melon, frog, horse; etc.), before the test, should be sure that the child can correctly understand this group of pictures named, then the tester stands behind the child, narrate each word (word), let the child point out the corresponding picture piece then gradually away from the child, until 3 meters distance. Until 3m distance, and the hearing loss can be analyzed according to the frequency of the consonants of the words that cannot be distinguished, normal children can distinguish each word of whispering intensity at 5m distance.
(b) Multiple choice picture test (picture vocabulary test) was applied to instruct the children to confirm the pictures by multiple choice method. 8 groups of test materials were used, each group contained 10 pictures, representing 10 words, and the children were asked to point out the said pictures according to the words spoken by the testers.