IHS ILE Exam (study for the written hearing aid dealers/fitters exam)

IHS ILE Exam (study for the written hearing aid dealers/fitters exam) What does decreasing the compression ratio do, and when would you use this? - ANS-Soft sound amplification is unaltered, but gain is increased for moderate/loud sounds. Most often used if a PT complains loud sounds aren't loud enough or sound "mushy" What does increasing the compression ratio do, and when would you use this? - ANS-Soft sound gain is unaltered, but gain for moderate/loud sounds is lowered. Most often used if a PT complains loud/moderate sounds are too loud or background noise is too loud. ** sometimes you use this on just certain frequencies, for example, high frequencies if they complain dishes are too loud, or low frequencies if they complain their voice is echo-y What happens when you raise a knee point, and when would you do this? - ANS-You will decrease gain for soft sounds and raise gain for moderate/loud sounds. Most often used if they hear soft sounds better than moderate ones ( like hearing the table across from them better than their own in a restaurant) or when they complain about hearing a HA's circuit noise. What does lowering the kneepoint do, and when would you do this? - ANS-Lowering the KP will lower gain for moderate and loud sounds, and increase gain for soft sounds below the original KP. Mostly used when a PT complains they can't hear soft sounds like soft voices, bird chirping, or ticking clocks. What are the two types of compression? - ANS-Input compression - when the input level of a HA determines when compression is activated. Output compression - when the output (input + gain) of the HA determines when compression is activated. What is Wide Dynamic Range Compression? - ANS-(WDRC) This is what most HA's utilize today, and allows the signal to be packaged withing a user's DR. Typically WDRC HA's have low (35-55 dB SPL) KPs and low (1:1 - 1:4) ratios What is the Compression Ratio? - ANS-The ratio of change between the input and output of a HA. This determines how much compression will occur. What is the Kneepoint? (KP) - ANS-The lowest level at which compression is applied What is Harmonic Distortion? - ANS-Harmonic distortion occurs when a single frequency is presented to the input of a hearing aid and the output contains the original frequency plus additional undesired frequencies that are harmonically related to the original frequency. ANSI uses a harmonic distortion test that measures the distortion rate at specific Hz. Frequency Response Curve - ANS-Used in ANSI testing. A gain curve is run with the input sound at 60 dB SPL to simulate conversation level. You get the frequency range calculation from this test. Reference Test Gain (RTG) - ANS-Used in ANSI testing. Input sound is set at 60 dB SPL to simulate conversation level; and then the HFA gain is adjusted to HFA-OSPL90 -77 dB. The answer is the RTG. Full On Gain (FOG)? - ANS-Used in ANSI testing. The HFA-FOG is measured and recorded w/ the input set at 50 dB SPL Maximum Output Curve ( OSPL90) - ANS-Used in ANSI testing. It's the max output of a HA. Input is set to 90 dB SPL to test. Notes the max at each tested frequency. HFA is noted from this test. What must be done to an aid before ANSI testing? - ANS-1- Occlude all vents on outside of aid 2- Set to test mode with gain full on, output at max, and bandwidth to max 3-Telecoil should be turned off and only turned back on when testing SPLITS What couplers do do you use with what instruments when ANSI testing? - ANS-HA-1 = ITE SB-1 = RIC and thin tube BTE's HA-2 = BTE What is a coupler? - ANS-A joiner for a HA that is designed off the vol of an average ear (2cc). Used to connect the HA to a testing box for ANSI tests. What is Adaptive Feedback Supression? - ANS-