Exam 1998 Question 2
" Frequency response graphs are useful for the description of systems. Explain how they may be used to: (i) assess the quality of audio equipment; (ii) explain the acoustics of speech production."
20 things you should mention:
- Frequency Response
- Frequency response graphs describe how a system:
- changes the amplitude (output cf input)
- of pure tones
- at a range of frequencies
- response is ratio O/I
- and commonly expressed in decibels
- Assess audio
- generate a FR for audio equipment by measuring response to pure tones at a arange of frequencies
- and plotting a graph (gfrequency characteristic)
- ideally audio equipment makes no change
- has a response that is flat
- real systems are also band-limited for practical reasons
- measure bandwidth at 3dB points
- response of chain of systems = product of responses
- Source Filter
- source-filter model
- independence of source and filter
- filter corresponds to frequency response of vocal tract
- shapes the excitation generated by larynx
- filter response a function of articulatory configuration
- and hence responsible for encoding much phonetic information
- diagram
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