1
00:00:00,440 --> 00:00:03,520
Speaker 1: Welcome to brain Stuff from how Stuff Works dot com

2
00:00:03,520 --> 00:00:08,080
Speaker 1: where smart Happens, Hi Marshall Brain. It used to be

3
00:00:08,119 --> 00:00:11,520
Speaker 1: that answering machines all used tapes, and some still do,

4
00:00:11,960 --> 00:00:15,320
Speaker 1: but today most answering machines are digital. They use the

5
00:00:15,360 --> 00:00:18,279
Speaker 1: same kind of technology that a CD or MP three

6
00:00:18,320 --> 00:00:21,520
Speaker 1: player uses. The first step in the process is an

7
00:00:21,560 --> 00:00:26,040
Speaker 1: analog to digital converter. This device samples the voice maybe

8
00:00:26,079 --> 00:00:29,640
Speaker 1: eight thousand times per second, and gives a digital value

9
00:00:29,680 --> 00:00:33,640
Speaker 1: to the intensity of each sample. A micro controller stores

10
00:00:33,680 --> 00:00:37,200
Speaker 1: all the samples in low power RAM or flash memory.

11
00:00:37,280 --> 00:00:39,640
Speaker 1: So let's say that a caller leaves a ten second

12
00:00:39,680 --> 00:00:44,400
Speaker 1: message that might translate into eighty thousand bytes of digitized data.

13
00:00:44,840 --> 00:00:48,280
Speaker 1: Those bites are stored at a specific address in RAM.

14
00:00:48,320 --> 00:00:51,239
Speaker 1: To play the message back, the micro controller reads the

15
00:00:51,280 --> 00:00:53,880
Speaker 1: eighty thousand bites from RAM and plays them through a

16
00:00:53,960 --> 00:00:57,800
Speaker 1: digital to analog converter. RAM or flash memory is a

17
00:00:57,880 --> 00:01:01,120
Speaker 1: high speed memory device, so the micro controller can erase

18
00:01:01,240 --> 00:01:04,080
Speaker 1: one of the messages, it can easily move the other

19
00:01:04,200 --> 00:01:07,360
Speaker 1: messages forward into the freed up space, or it can

20
00:01:07,400 --> 00:01:10,720
Speaker 1: store a new message in the blank space. Do you

21
00:01:10,760 --> 00:01:14,160
Speaker 1: have any ideas or suggestions for this podcast? If so,

22
00:01:14,280 --> 00:01:17,000
Speaker 1: Please send me an email at podcast at how stuff

23
00:01:17,000 --> 00:01:19,760
Speaker 1: works dot com. For more on this and thousands of

24
00:01:19,760 --> 00:01:24,280
Speaker 1: other topics, go to how stuff works dot com.