Exam Preview for 20482: Expansion: The Bottom line. The What, the W

Expansion: The Bottom line. The What, the When and the How.

Please note: exam questions are subject to change.

1. What is the fundamental purpose of all compression? To automatically change the amount of gain that the amplifier adds. To change the gain faster than the patient can change it using the volume control. To change the gain adaptively based on the changing input to the hearing aid. All of above
2. Which is true of Expansion? Expansion is a part of a total input dependent compression system that includes AGC-O and AGC-I Expansion monitors the output of the hearing aid and adjusts the gain accordingly. Expansion adjusts the gain to maintain comfortable audibility for soft and average input signals Expansion is a separate function unrelated to AGC-I and AGC-O compression
3. Which is not a characteristic that is shared by Expansion, AGC-I and AGC-O? Each utilizes input dependent gain changes in response to environmental changes. All utilize compression kneepoints and ratios to dictate when the compression commences and how much compression is applied. All have the same job of increasing gain as the input decreases. All have an effective range above and/or below the kneepoint where signals are managed differently.
4. Which is true regarding the basic jobs of compression? AGC-O's job is to make sure that loud sounds do not get too loud. AGC-I's job is to make sure that soft and average sounds are loud enough Expansion's job is to make sure that very soft sounds such as refrigerator hum or circuit noise remain audible a. and b. are true
5. Which is NOT true of the expansion kneepoint? It defines the point below which gain for very soft sounds receive less gain. It defines the point where the AGC-I linear range begins. The expansion kneepoint should remain at least 4 dB apart from the AGC-I kneepoint. The effective compression range for expansion is above the expansion kneepoint.
6. When adjusting compression function, the professional should consider: Avoiding higher expansion kneepoints to avoid suppressing critical speech cues. That the goal of expansion is to make sure that the hearing aid does not amplify very soft ambient sounds or circuit noise that the listener may not wish to hear. That whether a patient hears the circuit run or not can depend on how much gain for soft sounds the amplifier is generating and the degree of hearing loss. As long as the patient does not complain of microphone noise, or very low inputs, the expansion should be set as low as possible or off. All of the above
7. Which is true regarding the different compression functions? Each part of the total compression system has the same goal and job for managing gain. The compression system starts with the expansion range affecting very low inputs The expansion threshold marks the beginning of the AGC-I linear range At the expansion kneepoint, the gain being added will be the same as the gain for 50 dB inputs. b., c., and d. are true
8. he AGC-I compression range: Begins at the expansion kneepoint Begins at the AGC-I kneepoint Increases gain as the inputs increase Continues up to the AGC-O kneepoint b. and d. are true
9. When managing tinnitus using hearing aids with expansion the following is (are) true. Tinnitus patients already have sounds in their ears. The last thing they need is to hear a circuit noise or soft environmental sounds being amplified by the hearing aid. Higher expansion kneepoints can provide useful relief from tinnitus by quieting the circuit more aggressively. Continued amplification of circuit noise and soft ambient sounds can provide a masking effect for tinnitus. None of the above are true.
10. Which of the following questions should be asked when considering adjustment of the compression/expansion functions? Does the patient want or not want to hear the sound? What is the ultimate goal of the adjustment? What is the job that I want the compression to do? All of the above None of the above. These questions are irrelevant.