1. Forward Until Sound Program

2. NXT Sound Sensors

3. NXT Sound Sensors
How does the Sound Sensor detect sound? The Sound Sensor has a diaphragm membrane that is struck by sound waved, and vibrates them. The vibrating diaphragm contains magnets, whose vibrations induces (creates) an electrical current in a surrounding coil of wire. The NXT detects this current and interprets it into a Sound Sensor reading.

4. Forward Until Sound Program

5. Establishing The Threshold
On the NXT
Select the View Mode
Select Sound DB
Select Port 2
Position the robot in an area that is quiet to acquire the two sound readings as shown in the next two slides

6. Establishing The Quiet Threshold

7. Establishing The Clap Threshold

8. Calculate The Threshold

9. Motor Block One Details

10. Sound Sensor Block Two Details

11. Motor Block Three Details

12. Test Your robot. Will it stop when you clap?

13. Forward Until Silence

14. Forward Until Silence Sound Sensor Block Two Details
Wait for the Sound Sensor on Port 2 to get a Silent reading
Silence/Quiet=Sound Sensor value<Threshold value

15. Test your robot does it go Forward Until Silence

16. Calculating Thresholds Quiz
Would the robot classify the following Sound Sensor readings as Sound or Silence?
Sensor = 25 with Threshold = 40
Sensor = 65 with Threshold = 40
Sensor = 47 with Threshold = 54
Sensor = with No talking =30 and Whisper = 70
Sensor = with No Clap = 43 and Clap = 100

17. Calculating Thresholds Quiz Answers
a. Sensor = 25 with Threshold = 40
Sensor value is less than Threshold therefore it is silence
b. Sensor = 65 with Threshold = 40
Sensor value is greater than Threshold therefore it is sound
c. Sensor = 47 with Threshold = 54

18. Calculating Thresholds Quiz Answers
d. Sensor = with No Talking =30 and Whisper = 70
The threshold is (30+70)/2=50 The Sensor Value is less than Threshold, therefore it is No Talking. Intuitively - the Sensor value is closer to No Talking than Talking, therefore it is No Talking
e. Sensor = with No Clap = 43 and Clap = 100
The threshold is (43+100)/2=72 The Sensor Value is greater than Threshold, therefore it is a Clap. Intuitively - the Sensor value is closer to Clapping than No clapping therefore it is clap.