43:
and sent electronically over the network. The analogue signal is re-created at the receiving end of the network. When one of the parties does not speak, background noise is picked up and sent over the network. This is inefficient as this signal carries no useful information and thus, bandwidth is
97:
needs to be generated to compensate for the lack of background noise. The ingress end must therefore signal the egress end that silence suppression is in effect. For best results, the level of comfort noise being generated on egress should match that of the background noise at the ingress end.
47:
Given that typically only one party in a conversation speaks at any one time, silence suppression can achieve overall bandwidth savings in the order of 50% over the duration of a
62:(VAD) which dynamically monitors background noise and sets a corresponding speech detection threshold. This technique is also known as speech activity detection (SAD).
111:
Thus, silence suppression is generally an optional feature on telephony devices. In some cases, it is automatically turned on based on the characteristics of a call.
88:
Background noise detection may be difficult in some circumstances (relatively low speech level, or relatively high background noise level, for example).
142:
91:
When silence suppression is active, the line appears to have gone dead at the other (egress) end of the call. For this reason, so-called
39:
Voice is carried over a digital telephone network by converting the analog signal to a digital signal which is then
70:
25:
143:
Silence suppression and comfort noise generation (International
Engineering Consortium on-line education topic)
130:
59:
108:
Speech activity detection does not work well on non-speech calls (fax or modem communication, for example).
66:
51:. (While both parties may sometimes speak at the same time, there are times when both parties are silent.)
33:
157:
77:
55:
102:
40:
48:
29:
151:
120:
93:
125:
54:
Silence suppression is achieved by recognizing the lack of speech through a
21:
76:
For further bandwidth gains, silence suppression is normally done after
24:
to describe the process of not transmitting information over the
101:
Speech activity detection must occur very quickly, otherwise
8:
28:when one of the parties involved in a
7:
32:is not speaking, thereby reducing
14:
73:in GSM mobile telephone systems.
65:A similar principle is used for
1:
174:
71:discontinuous transmission
131:Voice activity detection
60:voice activity detection
67:Discontinuous Reception
18:silence suppression
78:echo cancellation
58:mechanism called
56:speech processing
165:
173:
172:
168:
167:
166:
164:
163:
162:
148:
147:
139:
117:
86:
12:
11:
5:
171:
169:
161:
160:
150:
149:
146:
145:
138:
137:External links
135:
134:
133:
128:
123:
116:
113:
85:
82:
49:telephone call
30:telephone call
13:
10:
9:
6:
4:
3:
2:
170:
159:
156:
155:
153:
144:
141:
140:
136:
132:
129:
127:
124:
122:
121:Comfort noise
119:
118:
114:
112:
109:
106:
105:might occur.
104:
99:
96:
95:
94:comfort noise
89:
83:
81:
79:
74:
72:
68:
63:
61:
57:
52:
50:
45:
42:
37:
35:
31:
27:
23:
19:
110:
107:
100:
92:
90:
87:
75:
64:
53:
46:
38:
17:
15:
20:is used in
41:packetized
158:Telephony
126:Talkspurt
84:Drawbacks
34:bandwidth
22:telephony
16:The term
152:Category
115:See also
103:clipping
44:wasted.
36:usage.
26:network
69:and
154::
80:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.