What are children hearing?

1. What are children hearing? Wendy McCracken and Imran Mulla University of Manchester

2. Objectives • Neurological basis for listening • Signal to noise and reverberation • The perceptual effects of hearing loss • To look at new approaches to understanding the listening environment of children • To consider ways in which children can be provided with access to good quality sound

3. Communication through speech • Primary mode of accessing mainstream classroom information • Complex chain of events that can be affected by the acoustic properties of the room, the maturity of the listener, the language skills of the listener, motivation and level of effort/fatigue

4. Hearing: peripheral Listening Cognitive effort exerted by the listener to understand the speech signal Response is at the level of the cortex Hearing /Listening

5. Following birth, the brain of a newborn is flooded with information from the baby’s sense organs. At birth, each neuron in the cerebral cortex has approximately 2,500 synapses. By the time an infant is two or three years old, the number of approximately 15,000 synapses per neuron (Gopnick, et al., 1999). This is about twice as many as an adult brain Neurological basis for listening

6. Synaptic pruning • Synaptic pruning eliminates weaker synaptic contacts while stronger connections are maintained and strengthened. • Experience determines which connections will be strengthened and which will be pruned; connections that have been activated most frequently are preserved. • Ineffective or weak connections are "pruned" It is plasticity that enables the process of developing and pruning connections, allowing the brain to adapt itself to its environment.

8. Neurological development • Stimulation of the auditory centres of the brain influence the actual growth and organisation of the auditory pathways Sharma, Dorman and Spahr, 2002] • The higher auditory brain centres are not auditory cognitive closure like adults [Bhatnagar, 2002; Chermak a& Musiek, 1997]

9. On going maturation • Recent studies suggest that complex neurological changes, including integration of information from the senses continue until the brain is mature, some time in the third decade of life [Geidd, 2004]

10. Children are not small adults! • A child does not bring a mature neurological system to the listening situation [Bhatnagar, 2002] • Children do not have language skills or life experience of adults to allow them to fill in the gaps or infer meaning. • All children require a quieter room and louder signal than adults

11. Dual tasks • There are many tasks that require infants and children to process simultaneously presented auditory and visual information • It is likely that both overshadowing and response competition affect the way children respond to these stimuli. • Evidence that executive function is not developed until the age of 10 years

12. Real classrooms Designed for learning ?

13. Real classroom as listening environments • Reverberation • Noise • Distance

14. Reverberation • The persistence of prolongation of sound • In highly reverberant rooms speech signals are delayed and overlap with direct sound • This may mask out the intended message of the speaker

16. Noise • Noise can be defined as any sound other than the signal [in this case speech] that you want to hear • Classrooms are dynamic learning spaces, noise is generated primarily by pupil activity

17. Children need the signal to be 15 dB louder than background noise [Ross, 92] Source Institute for Enhanced Classroom Hearing

18. Acoustic Environment in an Unoccupied Classroom Background Noise @ 35 dBA per ANSI Standard 12.60SNR = +15 dB Source Institute for Enhanced Classroom Hearing

19. Acoustic Environment in an Occupied ClassroomBackground Noise @ 45+ dBASNR = +5 dB Source Institute for Enhanced Classroom Hearing

20. Speech in quiet S/N +6 RT0.8

21. Noise It is hard for us to understand the difficulties children may face as adults have mature listening skills 1) the higher auditory brain centres are not fully developed until a child is about 15 years old 2) and children cannot perform automatic auditory cognitive closure like adults (intrinsic vs extrinsic redundancy).

22. Distance • Dydactic teaching is seldom the approach taken in classrooms • As the teacher moves round the level of their voice will vary considerably • The further a child is from the speaker the quieter the speech will be

23. Listening • “Listening” is the cornerstone of the educational system. • Children spend up to 70% of their school day listening. • Children are the biggest source of noise in the classroom.

24. Listening effort “When we want to remember something we have heard, we must hear it clearly because memory can be only as clear as its original signal…” [Doidge, 2007] For any listener poor acoustics mean that the listener needs to exert increased effort to be used to make sense of speech

25. Listening effort • Short term memory [STM] plays a crucial role in processing speech [ Choi, Lotto Lewis et al., 2008] • Where children are required to divide attention short term memory they may experience limitations due to STM constraints [Nittrouer and Boothroyd, 1990]

26. Complex working memory • Defined as the ability to manipulate and store material simultaneously • This shows a steep developmental slope up to the age of 16 years • All children attending schools require a good acoustic environment if they are to achieve their potential

27. Children who have a hearing loss • Face very specific challenges relating to the effects of deafness on the auditory system • Threshold elevation • Dynamic range reduction • Discrimination loss • Increased susceptibility to noise [simulation]

28. AUDIBILITY means that the speech is “heard” – but not heard clearly enough to distinguish specific speech sounds. • AUDIBILITY is carried by vowels – high energy, low frequency speech sounds. The low frequencies of 250 Hz and 500 Hz carry 90% of the power of speech, but only 10% of the intelligibility.

29. INTELLIGIBILITY means that the listener heard clearly enough to identify critical word/sound distinctions. INTELLIGIBILITY is carried by consonants – low energy, high frequency speech sounds. The frequencies of 2000 Hz and 4000 Hz carry 90% of the intelligibility of speech, but only10% of the power of speech. They are very weak speech sounds.

30. Children using amplification • Major opportunity to access speech signal and 85% deaf children in mainstream but: • Only as good as its management • Does not overcome poor acoustics • Are more significantly more adversely affected by poor acoustics than peers

31. Children who are vulnerable A positive listening environment is even more important for children: • who are deaf • have English as a second language • have an auditory processing problem • have learning disabilities. • have attention problems. • have behaviour problems. • have developmental disabilities. • have visual disabilities.

32. Summary • Classrooms are generally poor acoustic environments • Children’s listening skills are not fully developed until they are 15 • Children need a quieter, less reverberant learning environment than adults • Children do not develop control of executive function is not mature before the age of 10

33. Children’s listening environments at home • Little is known about the listening environment that young children experience • As part of a PhD study we have used LENA [Language Environment Analysis] • This uses advanced signal processing strategies to monitor the natural language environment of the child • It provides automatic analysis of data

34. LENA • Aim is to gain information on the overall quality of the language environment and general developmental status of the child [Oller et al., 2010: Xu et al., 2008] • Being used by some key researchers in the field –[Yoshinga-Itano 2010; Stremel-Thomas, 2010; Vohr, 2010]

36. LENA • Device weighs 60 grams • Single microphone • Data is recorded over the child’s waking hours, downloaded to USB • Automated language software analysis • The recoding is analysed through an iterative modelling process which segments the data

37. The segments components include: • Male and female adult • Key child • Other child, • Overlapping speech, noise, electronic noise silence and very low inter unit variation [Ford et al., 2008]

38. Lena report The analysis produces detailed reports including: • Adult and child word counts • Conversational turn word counts • Time specific information • Language specific measures such as Mean length of utterance • Data can be displayed in month, hour, day and 5 min segments

39. (LENA Research v3.1.2)

40. With special thanks to Imran Mulla

41. With special thanks to Imran Mulla

42. LENA The potential of using LENA is considerable: • to identify child/parent interaction • as a counselling tool • To identify noisy situations where FM would be useful Caveat: there are challenges as LENA is not designed to measure benefit from using FM

43. Typical classrooms • Listening is the basis for the key skill of literacy • Classrooms are acoustically hostile for children [+6 dB] • Dehaene[2009]: 20,000 hours of listening as a basis for reading • Pittman: Children with hearing loss require three times the exposure to learn new words and concepts due to the reduced acoustic bandwidth caused by the hearing loss.

44. Positive approaches to listening • Recognise challenges faced by all children • Improve levels of classroom control, planned activity sessions and group work • Use technology to improve situation for all pupils • Specifically with hearing aid users-proactive and sensitive management of amplification [mute button]

45. Dehaene, S. (2009). Reading in the brain: The science and evolution of a human invention. New York: Penguin Group Doidge, N. (2007). The BRAIN that changes itself. London: Penguin Books Ltd. Ford et al., 2008ITLR-03-2: The LENA Language Environment Analysis System: Audio Specifications of the DLP-0121 Http//:www.leanfoundation.org.Techreport.aspx/Audio_Specifications/LTR-03-2 Oller et al., (2010) Automated vocal analysis of naturalistic recordings from children with autism, language delay and typical development. Proceedings of the National Academy of Science 107(30 13354-13359 Xu et al., 2008 LTR-0402: The LENA Language Environment Analysis System: the Interpreted Time segments (ITS) file Http//:www.lenafoundation.org.Techreport.aspx/Audio_Specifications/LTR-04-2 Yoshinga-Itano C. (2010) The missing link in the language assessment for children who are deaf or hard of hearing http://www.lenafoundation.org./pdfLENA-conf-2010/Presentations/LENA-Conf-2010-C-Yoshinaga--itano.pdf Stremel-Thomas, K. (2010) Determining pre-post cochlear implant outcomes for young children with deaf-blindness through LENA technology http://www.lenafoundation.org./pdfLENA-conf-2010/Presentations/LENA-Conf-2010-Katherine-Stremel.pdf Vohr,B (2010) Studies of Early Language Development in high-risk populations. http://www.lenafoundation.org./pdfLENA-conf-2010/Presentations/LENA-Conf-2010-Betty-Vohr.pdf ;; Vohr, 2010]