DSP 1 CORE EXAM MANUAL QUESTIONS AND ANSWERS
GRADED A+
✔✔Once the signal has been "digitized" it is converted into - ✔✔a binary digit or a bit.
✔✔Digital hearing aids use strings of numbers (AKA...) - ✔✔algorithms
✔✔After the the signal is manipulated it can be... - ✔✔Amplified or filtered or more
complex signal processing.
✔✔After the representation of the signal is in the form we want (via algorithms)... - ✔✔it
is converted back into an analogue signal for delivery to the listener.
✔✔The modified numbers will be converted back into an analog signal using... -
✔✔digital-to-analog (DAC) converter
✔✔Digital hearing aids features: - ✔✔Programmability
-Technical superior to analog but until digital hearing aids used logic capabilities
potential was not available
Multiple Memories
- Great potential for specific improvements
Computer-based fitting
- Retrieving information, digital controls of test stimuli and the programming of hearing
aids
Adaptive adjustments
-Control signal processing in the hearing aid as the acoustic environment changes
Noise Reduction
- Didn't work until we had several microphones and now wireless link between ears
Feedback Cancellation
-Enable adaptive adjustment of both amplitude of both amplitude and phase thereby
allowing for cancellation of acoustic feedback
✔✔Specification of DHA (x6) - ✔✔-Instructions per second
-Sample rate
-Number of bits
-Current Consumption
-Processing delay
-Physical Size
✔✔MIPS definition - ✔✔million instructions per second
, 40MIPS= 40 million instructions per second
✔✔More complex signal processing schemes require - ✔✔a greater number of IPS
Ex: compression more complex than peak clipping
✔✔Increased IPS will increase current consumption and therefore decreases -
✔✔battery life
✔✔A/D Conversion definition - ✔✔the process of obtaining a digital representation of
sound through sampling and quantization
✔✔Sampling - ✔✔the process of measuring the signal amplitude at discrete points in
time
✔✔Quantization - ✔✔measurement of amplitude and assignment of numeric values at
each sample
✔✔D/A Conversion - ✔✔uses strings of numbers that precisely represent the amplitude
of the processed signal
✔✔Methods used in both A/D and D/A - ✔✔oversampling and undersampling
✔✔Sampling Rate AKA sampling frequency - ✔✔is the number of samples per second
(measured in Hz) and is used to define the discrete time intervals of the digital
representation of the sound
✔✔Sampling Period definition - ✔✔the time between each sample (this is the inverse of
the sampling rate)
Example: Sampling FQ is 1000 Hz, the sampling period is 1/1000 samples per second
or 1ms
✔✔Nyquist Theorem definition - ✔✔how fast the sampling rate needs to be to
accurately represent the true signal
✔✔Minimum necessary sampling rate is - ✔✔two times the highest frequency
✔✔Sampling frequency describes how many times per second - ✔✔the hearing aid
samples the input signal
✔✔A hearing aid can only amplify sounds up to about - ✔✔40% to 45% of the sampling
rate (theoretical maximum 50%)
GRADED A+
✔✔Once the signal has been "digitized" it is converted into - ✔✔a binary digit or a bit.
✔✔Digital hearing aids use strings of numbers (AKA...) - ✔✔algorithms
✔✔After the the signal is manipulated it can be... - ✔✔Amplified or filtered or more
complex signal processing.
✔✔After the representation of the signal is in the form we want (via algorithms)... - ✔✔it
is converted back into an analogue signal for delivery to the listener.
✔✔The modified numbers will be converted back into an analog signal using... -
✔✔digital-to-analog (DAC) converter
✔✔Digital hearing aids features: - ✔✔Programmability
-Technical superior to analog but until digital hearing aids used logic capabilities
potential was not available
Multiple Memories
- Great potential for specific improvements
Computer-based fitting
- Retrieving information, digital controls of test stimuli and the programming of hearing
aids
Adaptive adjustments
-Control signal processing in the hearing aid as the acoustic environment changes
Noise Reduction
- Didn't work until we had several microphones and now wireless link between ears
Feedback Cancellation
-Enable adaptive adjustment of both amplitude of both amplitude and phase thereby
allowing for cancellation of acoustic feedback
✔✔Specification of DHA (x6) - ✔✔-Instructions per second
-Sample rate
-Number of bits
-Current Consumption
-Processing delay
-Physical Size
✔✔MIPS definition - ✔✔million instructions per second
, 40MIPS= 40 million instructions per second
✔✔More complex signal processing schemes require - ✔✔a greater number of IPS
Ex: compression more complex than peak clipping
✔✔Increased IPS will increase current consumption and therefore decreases -
✔✔battery life
✔✔A/D Conversion definition - ✔✔the process of obtaining a digital representation of
sound through sampling and quantization
✔✔Sampling - ✔✔the process of measuring the signal amplitude at discrete points in
time
✔✔Quantization - ✔✔measurement of amplitude and assignment of numeric values at
each sample
✔✔D/A Conversion - ✔✔uses strings of numbers that precisely represent the amplitude
of the processed signal
✔✔Methods used in both A/D and D/A - ✔✔oversampling and undersampling
✔✔Sampling Rate AKA sampling frequency - ✔✔is the number of samples per second
(measured in Hz) and is used to define the discrete time intervals of the digital
representation of the sound
✔✔Sampling Period definition - ✔✔the time between each sample (this is the inverse of
the sampling rate)
Example: Sampling FQ is 1000 Hz, the sampling period is 1/1000 samples per second
or 1ms
✔✔Nyquist Theorem definition - ✔✔how fast the sampling rate needs to be to
accurately represent the true signal
✔✔Minimum necessary sampling rate is - ✔✔two times the highest frequency
✔✔Sampling frequency describes how many times per second - ✔✔the hearing aid
samples the input signal
✔✔A hearing aid can only amplify sounds up to about - ✔✔40% to 45% of the sampling
rate (theoretical maximum 50%)
