Digital Signal Processing Reference
In-Depth Information
Chapter 4
Language as a carrier of information
It is always interesting to see what a short step it is from the fundamental principles of
physics to their practical application. A knowledge of fundamental principles is
absolutely essential. In this context, however, the word "theory" for many people has
unpleasant associations, probably because it is mostly described by means of abstract
mathematical models. This is not the case in this topic.
2,0
Time domain
1,5
1,0
0,5
0,0
-0,5
-1,0
-1,5
-2,0
-2,5
-3,0
........ I .............................
o.........................
u................
-3,5
0.25
0.50
0.75
1.00
s
0,125
Frequency domain
0,100
0,075
0,050
0,025
0,000
250
500
750
1000
1250
1500
1750
2000
2250
2500
2750
3000
3250
3500
3750
Hz
Illustration 67:
The sequence „I owe you“ (IOU) as a one-off signal in the time and frequency domain
Even a short sequence such as "I owe you" has a very complicated structure in both the time and frequency
domains. In the time domain 5 phases are recognizable. The initial "i", the transition phase from "i" to "o",
the "o"-phase, the transition phase from "o" to "u", and the final, slightly longer "u"-phase. The initial
transient phase and the final concluding phase could be added. The frequency spectrum shows us that it
does not make sense to determine the frequencies over the entire length of the word. Many frequency
patterns are interlocking. It is obviously more sensible - as shown in Illustration 51 - Illustration 49 - to
analyse individual sections of the word separately. Special techniques have been developed for this pur-
pose ("Waterfall-analysis", see Illustration 68).
