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Audiometry Equipment The present invention relates to a device for testing the hearing and audio response in young children The audio testing of young children can be carried out using visual reinforcement audiometry (VRA) which combines audio and visual signals to assess hearing levels.
The child learns to associate a sound with a pleasant stimulus (e. g. a toy) and will then turn towards the sound alone, providing a behavioural indication that the sound has been heard, however children are easily bored and can cease to respond to the visual stimulus before the end of a testing session.
The established technique of visual reinforcement audiometry is used for behavioural hearing tests in children between the ages 6 months to 3 years. The technique enables hearing threshold assessment using frequency specific audiometry signals such as pure tones and narrow-band noise. It utilizes the orientation reflex that develops in infants at about the age of four months. Children of this age group (ages 6 months to 3 years) would turn (their heads) to locate interesting visual and auditory stimuli. In current practice of using visual reinforcement audiometry a child would be conditioned to associate a moderately loud sound signal with an attractive visual stimulus (visual reinforcement), e. g. a toy that moves. Once the association and the interest in the visual stimulus and the sound is established, the test procedure is extended to test response to threshold (softest detectable) auditory signals, without the child being bored or distracted (habituating).
Sound stimuli are produced by using audiometers and delivered via loudspeakers. Toys are kept in the vicinity of the loudspeakers. They are best hidden in boxes with dark tinted Plexiglas panels in front so that the visual stimulus is hidden when there is no sound presentation. The illumination within the box is switched on to make the toy visible when required, as a reward to turning and locating the sound Children
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habituate to the visual stimulation relatively quickly therefore several boxes arranged on a wall or stacked on top of each other as a lower is used The equipment is bulky and suitable only for hospital (3tier) audiology departments We have devised improved equipment for visual reinforcement audiometry which is compact and more flexible.
According to the invention there is provided visual reinforcement audiometry equipment which equipment comprises a hand puppet having an audiometer located within it, which audiometer is able to generate sound impulses of varying intensities.
Preferably the control which controls the audiometer signal is mounted within the puppet so that the clinician using the puppet can easily control the emission of the signal.
By hand puppet is meant any object which is able to fit on a hand and be moved or manipulated by that hand. Hand puppets are sometimes referred to as glove puppets or arm puppets and a vast range of real and imaginary people, characters, animals etc. as well as objects such as cars, ships, aeroplanes etc. have been made in the form of such puppets. Any such puppet which is able to attract the attention of a child can be used in the present invention. A feature of hand puppets is that can be in the form of a character etc. which the child immediately recognizes from other activities such as television, books, films etc. and to which the child is immediately attracted.
In one embodiment of the invention the puppet can be in the form of a removable outer skin or covering over a frame or skeleton which fits on the hand and which contains the audiometer. In this way a range of different characters can be easily interchanged to maintain the interest of the child and to reduce boredom and the interchangeable skins would enable the clinician to maintain the child's interest in the test, reducing the chance of habituation.
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There can be a motor of other device which operates the movement of the mouth of the puppet in coordination with the emission of a signal from the puppet to provide further interest to the child The audiometer can be any audio transmitter which is capable producing the appropriate sounds and such transmitters are readily available in a compact size and form part of the puppet. The sounds generated can be those used in conventional visual reinforcement audiometry and are used in the same way. The equipment can also include facility to record a short audio clip, like the child's name, and replay this during play and testing to raise the child's attention The audiometer controls can be mounted on or within the puppet so that they can be easily operated by the clinician and this facilitates the adjustment of the test to the responses of the child.
Other devices can be incorporated in the equipment such as a sound pressure meter and an LCD display of frequency and intensity settings on the back of the'forearm'of the puppet.
For ease of use in a range of environments a battery, preferably rechargeable, can power the audiometer and, as arm puppets are not bulky, the invention also provides a container containing visual reinforcement audiometry equipment of the invention, interchangeable'skins'to change characters and a battery charger all as a portable set in a carry case.
Closed circuit equipment such as insert ear phones, head phones and bone conductors can be connected to the puppets to enable access to more exacting audiometric data such as bone conduction thresholds, ear specific pure tone audiometric (PTA) thresholds. This would make the equipment sophisticated enough for use in 3rd tier audiology clinics and the ability to discard the towers of visual renforcer boxes and
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walls fixed with them, as used in existing clinics, would reduce the clutter in test booths.
It is a feature of the invention that the portability of the equipment enables clinicians to use VRA in 2nd tier clinics, in sound-treated (as opposed to sound-proof) rooms and the effective screening and diagnosis of children with hearing loss by VRA would reduce the bulk of normal hearing young children referred to third tier hospital clinics as'difficult to test'.
The invention is illustrated in a test protocol which can be modified and used flexibly to suit individual children Two techniques are described, one for younger children (6- 8 months), children who are developmentally delayed, or have physical disability which prevents them from rapid accurate localization of the sound stimulus and another for older normally developing children. However the rigour of recording responses and presentation of stimuli should be adhered in the same manner as standard VRA. As in standard VRA there are two components to testing-threshold estimation (Auditory sensitivity) and localization. The latter is not tested in younger children (6-8 months), children who are developmentally delayed, or have physical disability causing difficulty turning their heads. Testing should commence with the former. Tests require two testers Tester 1 will be behind the child (and the parent) mostly presenting sound stimuli, and tester 2 will be in front of the child (and the parent) controlling the attention of the child and establishing the initial reinforcement.
The invention is illustrated in the accompanying in drawings which show an embodiment of the invention Fig. 1 shows a side view of the puppet Fig. 2 shows a front view of the puppet Fig. 3 this shows a rear view of the puppet
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Referring to figs. 1 there is a glove (1) made of elastic cloth, this fits over a the metal/plastic body of the audiometer (4) and can be removed and changed to another character as required. The finger (2) fits within a recess in the puppet and can push the control button (3) to produce the sound stimulus. There is moveable mouth (5) pivoted to be moved by an electric motor. There is a speaker (6) and, on the wrist, there is the control panel (7) of the audiometer, a microphone (8) to record a voice, closed circuit output point (9) for headphones and insert ear phones and on/off switch (10).
Referring to fig. 2, this shows a front view and there is the eye of puppet (12), e. g. made of shiny plastic, middle and ring fingers (15), button (16) to control the mouth of the puppet which is pressed by middle and ring fingers (15), cloth mouth of the puppet (17), finger (19) within the cloth cover of the puppet-the thumb and little fingers move the two arms. The audiometer is fixed to the hand by latch of wristband (22) formed of metallic links (23).
Referring to fig. 3 this shows a rear view of the puppet and there is recess (13) for index finger with the switch for sound stimulus inside, recess (14) for the middle and
ring fingers (15), LCD display showing stimulus type (18) e. g frequency (kHz), white noise, voice etc. switch (29) to toggle above LCD, switch (31) to toggle LCD display below, LCD display of stimulus intensity (dB) and control panel (33).
For right handed individuals a left handed puppet should be used, and vice versa This leaves the dominant hand free to adjust the control, to write and document the results.
The puppet is held on the arm and hand by the metallic clasp, similar to the flexible linked metal strap used in wristlets. The circumference of the strap is adjustable to each individual. The glove of elastic cloth gives the puppet its character and is changeable.
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In use the clinician puts the puppet on his hand and adjusts the parameters of the sound signal for the test. The clinician controls the sound signal by pressing on button (3) and on button (16) to move the puppet's mouth (5). If a recorded message is to be used this can be recorded through microphone (8) and activated through switch (13).
The parameters of the stimulus type is displayed on display (18) controlled by switch (29) and the parameters of the sound are displayed on the display (32) controlled by switch (31).
The use of the equipment in accordance with the protocols referred to above is set out below.
1. Test protocol for younger children (6 - 8 months), children who are developmentally delayed, or have physical disability causing difficulty turning head Tester I Stands behind the child on the parents lap.
When conditioning is established sound of same intensity and frequency is made behind the child using the hand held audiometer of the invention.
When conditioning is established reduce sound intensity and obtain threshold response Obtain results for frequencies 0.5, 1,2, and 4 kHz Tester 2 Conditions to one side choosing the direction of the ear most likely to have normal hearing with a mid frequency warble tone (if child lacks interest try narrow band noise) at an intensity around 60-70 dB sound from the puppet audiometer of the invention. The puppet (on the testers arm on the side chosen for conditioning) is first hidden under the table. Conditioning is established by bringing the puppet out from under the table on one side as the sound is produced. When the sound is absent the tester centralizes the child's attention with low-key play (spinning top/ball) on the middle of the table; Tester 2 still continues to show the puppet when the sound occurs - this maintains the reinforced conditioning, (but this time transferred to or substituted by the sound from behind the child). Checks for established definite eye and head turn
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towards renforcer by slightly delaying reward. Alternates control of the child's attention to the centre and to the glove puppet popping out from under the table 2. Test protocol for older children Tester 1 Stands behind the child who is on a chair in the centre of the table, facing tester 2. The parent sits on the side that is not chosen for testing.
Conditions to one side choosing the direction of the ear most likely to have normal hearing with a mid frequency warble tone (if child lacks interest try narrow band noise) at an intensity around 60-70 dB sound from the puppet audiometer fixed on the testers left arm When conditioning is established reduce sound intensity and obtain threshold response Obtain results for frequencies 0.5, 1,2, and 4 kHz Check for ability to localize sound, offering sound (and visual reinforcement by the puppet) from either side from behind Tester 2
Sits in front of the child controlling the child's attention and observing responses. When the sound is absent the tester centralizes the child's attention with low-key play (spinning top/ball) on the middle of the table. If the child keeps on checking for the puppet and sound from behind him (Often seen in older children), get his attention to
the centre with another arm puppet. Creating equal interest.
Checks for established definite eye and head turn towards renforcer Control of the child's attention to the centre when there is no sound.