7. Tone Burst Abr

Front 1

4000 Hz

Back 1

Front 2

1000 Hz

Back 2

Front 3

500 Hz

Back 3

Front 4

advantages of click-based ABR?

Back 4

clicks evoke a large wave V

response that is relatively easy to read

Front 5

What is the limitation of click-based?

Back 5

measures made with clicks are correlated w later behavioral thresholds in the 2-4 kHz region

Front 6

What does the tone-burst ABR test provide

Back 6

• more frequency-specific results than click-ABR
• avoiding most configuration problems (cookie bits audiograms, and rising configuration)
• wave they elicit are less robust in appearance than click evoked wave V (making them harder to read)

Front 7

both click and TB ABR should be used in correlation to obtain the most specific information

Back 7

...

Front 8

polarity

Back 8

alternating (instead of regular rarefaction used in click ABR)

• minimizes possibility of a frequency following response
• only exception is at 500 Hz (may need to experiment with polarity - try condensation first)

Front 9

ramping

Back 9

refers to how the rise and fall of the tone is shaped

• blackman - type used in most commercial ABR units
• reduces spectral splatter
• increases the frequency specificity of the TB

Front 10

rise/fall times

Back 10

• duration of the stimulus
• times vary depending on the frequency (rule of thumb: longer times for lower frequencies)

Note: can use a brief TB - provides more well formed waves but less frequency specific

Front 11

suggested durations for rise/fall times

Back 11

Front 12

correction factors and normative data

Back 12

• normative data (dBnHL) is needed for each clinic based on the specific parameters of the system, characteristics of the room, type of transducer used
• correction factors and normative data for evoked potential systems differ by manufacturer
• contact the manufacturer to determine how the normative data was obtained and seek the manufacturer recommendation for your clinic's specific system

Front 13

example of correction factor for 500 Hz audiometric thresholds at 0 dB HL

Back 13

Front 14

400 kHz tone

Back 14

Front 15

1 kHz tone burst

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Front 16

500 Hz TB

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