KidsAudiologist

Posts Tagged ‘science

From this month NHS England (briefly known as the NHS Commissioning Board) takes over responsibility for commissioning specialist services for deaf children. This includes specialist implantable devices such as cochlear implants, bone anchored hearing aids and middle ear implants etc. Bilateral cochlear implants are currently and continue to be funded in line with NICE recommedations which children have a right to access under the NHS Constitution.

This month NHS England have announced their clinical access policies for bone anchored hearing aids and active middle ear implants. These are important because they relate to services that don’t have NICE recommendations and were previously commissioned locally by Primary Care Trusts and were subject to wide variation in provision. In summary:

Bone anchored hearing aids

  • are of safe and of proven benefit
  • should be provided in a specialist centre doing at least 15 a year. The team should include an ENT surgeon, audiologist, paediatric anaesthetist and speech and language therapist.
  • for children with microtia their care must be coordinated by a multidisciplinary team that can provide appropriate hearing and reconstructive support.
  • early intervention is vital and children born deaf should be provided with a bone anchored hearing aid on a soft headband until they are old enough for surgery.
  • funding will be available for children with bilateral conductive hearing loss to have bilateral bone anchored hearing aids if multidisciplinary assessment suggests that this would provide children with the best hearing environment in the classroom situation.
  • although bone anchored hearing aids would not normally be funded for children with unilateral deafness, an ‘exceptional case’ request can be made centred on information regarding the child’s development, audiometry results and communication needs.
  • and for the first time service providers will be expected to collect and provide audit data on request.

“Documents which have informed this policy – The National Deaf Children’s Society. Quality Standards in Bone Anchored Hearing Aids for Children and Young People. 2010″

Middle Ear Implants

Middle ear implants are a relatively new technology and very few children world-wide have been fitted with them. The evidence base is therefore almost non-existent at the current time. For these reasons it was not unexpected that active middle ear implants will not be routinely commissioned and will only be used as part of a recognised and structured clinical research project. However, they will be commissioned in the following limited circumstances:

  • Bilateral sensorineural hearing loss when conventional hearing aids have been used and found to be medically unsuitable due to conditions of the external ear.
  • Mixed hearing loss when conventional hearing aids have been used and found to be medically unsuitable due to conditions of the external ear and when a bone anchored hearing aid has been implanted and been associated with medical problems of the soft tissues or loss of fixture on more than one occasion.
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Children in the UK who are clinically suitable candidates and whose family chooses this option for them, have been offered bilateral cochlear implants since 2009. This followed recommendations made by the National Institute for Health and Clinical Excellence (NICE) who also said that children who had one cochlear implant prior to their guidance being published could be offered a second implant in the other ear (sequential implantation). At the time the evidence base was poor due to the small number of studies and the small numbers of participants, but NICE were persuaded that there were benefits to children having two implants including improved speech understanding in noisy situations, directional perception of sound, easier and less exhausting listening, and prevention of auditory deprivation and impaired development of central pathways by early stimulation of the auditory nerves. Within the guidance NICE recommended further research into the benefits of bilateral cochlear implantation in children and plan to review the evidence and their recommendations in the future.

As a result of this recommendation 15 cochlear implant centres across the UK formed a consortium and agreed on appropriate test procedures to audit the benefit children receive from bilateral cochlear implants. This group now have data from around 900 children and will be presenting their findings at a conference in Southampton on 11th April 2013. The conference is free to attend for adults and parents of children who use cochlear implants, and costs £50 for professionals. The National Paediatric Bilateral Audit website includes more information on the research, some preliminary results and online booking form for the conference.

They’re popping up everywhere and are chosen for their status providing renewable and clean energy – wind farms. Earlier this month I was asked if I could answer a couple of questions about how wind turbines may impact on the hearing, and hearing aid / cochlear implants, of local residents. I have to admit to not really knowing anything about them so I put the question out on Twitter too…

… and although I didn’t get any responses that answered the question I did get some from other users who said they’d be interested in what I found out. So here’s a summary of what I learnt after some research, but I’m still learning so do add any comments with further evidence if you have it.

Q 1. Is there is any research on the implications for deaf people with hearing aids of living near to turbines?

A. No. There is no research, literature or other evidence (that I can find) of any positive or negative impact on hearing aids, cochlear implants or their wearers living near wind turbines. I can find two statements written by members of the public saying that turbines cause problems for hearing aid / cochlear implant users but cannot find any fuller description, case study, or evidence as to why this should be.

and

Q 2. Can you offer a professional opinion about the impact on of the turbine on a young person’s hearing and possible damage?

A. What I have established in relation to wind turbines and the ear/hearing:

  • There is no evidence that the noise generated by wind turbines causes hearing loss, and wind turbines are not loud enough to cause hearing loss.
  • It is known and widely acknowledged that wind turbines generate significant levels of infrasonic acoustic energy (noise that is below the frequency range that the human ear detects as sound).
  • There is some limited lab-based research evidence  (such as this) that suggests infrasonic sound (vibration) may cause some disruption or abnormal stimulation of the inner ear (cochlea and vestibular system) that may form the basis of the symptoms of ‘wind turbine syndrome’. These symptoms include tinnitus, vertigo, disturbed sleep, headaches, memory and concentration deficits, irritability and anger, fatigue and loss of motivation.
  • Wind turbine syndrome is not experienced by the majority of people living near turbines. The data may be difficult to establish as those closest to the turbines (ie those who rent land to the energy companies) are often motivated to be positive about turbines due to financial incentives, and/or gagging clauses in contracts that prevent them saying anything negative about them. But many of the symptoms can also be explained by other factors such as stress and annoyance etc.
  • Planning guidelines in the UK says that turbine noise should not exceed 5 decibels above background, ambient noise. A wind farm produces a noise of about 35-45 decibels at a distance of 350m. Rural night-time background noise typically ranges from 20 to 40 decibels. No indoor levels are specified.
  • Most hearing aid wearers would be able to follow a close one-to-one conversation easily in this level of background noise.
  • In terms of background noise levels and the effect on hearing aid wearers it would be my opinion that if these levels were accurate and maintained, that outdoors the natural noise of the wind would be likely to be more of a hindrance than the turbine noise to the hearing aid or cochlear implant wearer (wind blows over the microphone and is amplified, wind also carries voices away from the listener etc). Indoors it is unlikely that these levels of background noise from outside would be significant or even heard. These background noise levels are certainly a lot lower than the average town or city dweller experiences most of the time.

I have located just one document for audiologists “Wind-Turbine Noise; What Audiologists Should Know” (Audiology Today, Jul/Aug 2010). It includes lots of information on the acoustics, infrasonic vibration levels, and the potential health problems that could be associated with wind turbines (such as tinnitus and vestibular disturbance) but is clear that the levels generated aren’t loud enough to cause noise damage and makes absolutely no mention of problems associated with hearing aids or cochlear implants.

There is probably still much we don’t know about the turbine technology, as well as the potential impact on the technologies on the human body. At the moment audiologists serving populations in areas where there are wind farms should be aware of potential health problems that patients may complain of. But I can find no evidence of any significant negative impact on existing hearing loss or on any hearing aids or cochlear implants that are worn.

Further reading

Wind turbine sound and health NHS Choices, January 2010

Scientist Challenges the Conventional Wisdom That What You Can’t Hear Won’t Hurt You June 2010

Analysis of How Noise Impacts are Considered in the Determination of Wind Farm Planning Applications Hayes McKenzie Partnership, June 2011

Wind myths: Turbines can damage your health February 2012

Hansard – Written Answers (Wind Power), 27th March 2012

I wanted to share a couple of excellent articles by Dr Carol Flexer, Ph.D. on the importance of early hearing aid fitting and use, & associated development of the auditory brain…

“Hart and Risley (1999) studied children from professional families and determined that they have heard 46 million live-spoken words by age 4. This is the magnitude of practice that is critical. This speaks volumes to the fact that less than every waking hour of technology use will not cut it for children with hearing loss. Dehaene (2009) talked about the listening basis for reading, and children with hearing loss require three times the exposure to learn new words and concepts because of reduced acoustic bandwidth compared to typical hearing peers.”

The Auditory Brain: Conversations for Pediatric Audiologists (2011)

“Robbins et al. (2004) found that skills mastered as a course of normal development result in developmental synchrony. Therefore, it appears we are pre-programmed to develop specific skills during certain periods of development. If those skills can be triggered at the intended time, we will be operating under a developmental and not a remedial paradigm. That is, we will be working harmoniously within the design of the human structure.”

Neuroplasticity is greatest during the first 3 ½ years of life; the younger the infant, the greater the neuroplasticity. Rapid infant brain growth requires prompt intervention, typically including amplification and a program to promote auditory skill development. In the absence of sound, the brain re-organizes itself to receive input from other senses, primarily vision; this process is called “crossmodal re-organization” and it reduces auditory neural capacity. Early amplification or implantation stimulates a brain that has not yet been reorganized, allowing the brain to be more receptive to auditory input resulting in greater auditory capacity.”

Auditory Brain Development: The key to developing listening, language and literacy (2012)


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