•The nature of sound•Types of losses

•Possible causes of hearing loss•Educational implications

•Preparing students for hearing assessment

The nature of sound A wave phenomenon with two dimensions

1. Frequency (Hz) - Hertz (cycles per second)- the number of vibrations of air particles per second: measured in Hertz- the human ear has a frequency range of approximately 20-20,000 - typically hearing is tested from 250-8000 Hz

Hz Low and high frequencies – impact on speech discrimination:

Psychological attribute which corresponds to frequency is pitch

Low frequency is perceived as low pitch and high frequency as high pitched sounds

Middle C on a piano is 250Hz, one octave below is 125 Hz

High pitched sounds include: a soprano voice, a doorbell

In general, vowel sounds are low-pitched and consonant sounds are high frequency sounds

2. The other dimension is intensity, measured in decibels (dB)“loudness”Usable hearing is from 0-120 dBdBs are intensity ratios20dB is not double of 10dB, but 100 times

greaterThe strongest sounds an average person

can hear without pain can be as much as 10 million times greater in intensity than a sound that is barely audible

For example:- 20 dB a whisper at four feet- 50 dB - quiet auto ten feet away-60-70 dB - normal conversation at three feet- 90 dB - pneumatic drill at ten feet

Speech acousticsSpectral characteristics make sound

complexVowels are lower frequency - generallly

having their most intense frequency components below 750 Hz

Consonants are composed of higher frequency sounds often consisting of a wide range of frequency components

In addition, vowels and consonants also differ in the amount of acoustical energy they produce

For an equivalent amount of vocal effort, the range between the loudest vowel (the o sound in the word dog) and the softest consonant (th sound) - is 28 dB

Vowels are therefore the most intense sounds heard in speech, while consonants are considerably less intense

However, consonants carry the most information

Consonants above 1000 Hz provide 60% of speech intelligibility, while vowels below 500 Hz provide only 5% of speech intelligibility

<Illustration>Thus, shouting at an individual with a

sensorineural hearing loss will do little to improve comprehension because the vowels will be the louder and the consonants will continue to be less audible

For this reason even mild hearing losses of 30-60 dB can have a big impact on speech intelligibility

Types of lossConductive

Sensorineural impairments

Mixed impairments

Central auditory impairment

Follow up to formal assessmentInterpreting audiograms - this is the role of

the audiologistThe job of the educational team is to get as

much information from the audiologist and the speech therapist about the nature of the speech sounds that the student can hear - with and without aids

Educational Decisions related to communication strategies for students with hearing impairments and deafness

Will you use visual aids?

Will you use a combination of gestures or signs and visual symbols?

Choosing a communication system – the issuesAmerican Sign Language (ASL)Oral languageCochlear implantsCombination approaches

Educational ImplicationsLiteracy: issues in teaching children who are

deaf to readSame language community issuesTeachers trained in working with

children/youth with hearing impairments and deafness

Social supports and friendship development

Least restrictive environmentParticipation in the core curriculum with

support for language and social engagementInterpreters, interveners, and support

teachersSigning community – same-language

community