Acoustic sensor

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Quick Questions

Shade in the A or B circle for each question.

1. What does an acoustic sensor detect?

A Light

B Sound

2. Which data can an acoustic sensor capture?

A The level of a sound

B The pH of a liquid

3. A burglar alarm uses an acoustic sensor. What is it listening for?

A A sound such as breaking glass or a forced door

B A change in air temperature

4. A school wants to check how loud its canteen gets at lunchtime. Which sensor is the best choice?

A Acoustic sensor

B Pressure sensor

5. Which statement is true?

A An acoustic sensor can only measure the temperature of a room

B An acoustic sensor can detect that a sound is present

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1IF soundLevel > 85 THEN		AAn acoustic sensor detects sound, not humidity, so the data captured is the wrong type
2IF soundDetected = TRUE THEN		BThe acoustic sensor reading is compared with a limit to check whether a noise is too loud
3A noise monitoring system uses an acoustic sensor to measure how loud the sound is		CThe acoustic sensor reports that a sound is present, for example in a burglar alarm
4A glass-break detector sets off an alarm when its acoustic sensor picks up a loud, sharp sound		DIF soundLevel > 90 THEN SoundAlarm()
5humidity ← ReadAcousticSensor()		EThe output does not match the purpose of a noise monitor, which should warn about loud sound not switch on a light
6IF soundLevel > 85 THEN LightOn()		FnoiseLevel ← ReadAcousticSensor()

Definitions

acoustic sensor

Fill in the Blanks

Complete each line of code by filling in the missing parts.

IF soundLevel _ 80 THEN OUTPUT "Too loud" ENDIF

IF soundLevel > 80 THEN ______ "Noise warning" ENDIF

alarm ← FALSE IF soundDetected = ____ THEN alarm ← TRUE

_____ monitoring = TRUE DO soundLevel ← READ_SENSOR(acoustic) ENDWHILE

_____ ← 85 soundLevel ← READ_SENSOR(acoustic) IF soundLevel > limit THEN

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A level ← ReadAcoustic()

B IF level > 80

C OUTPUT "Too loud"

D ENDIF

Question 2

A REPEAT

B sound ← ReadAcoustic()

C IF sound < 60 THEN

D SoundAlarm()

E ENDIF

F UNTIL FALSE

Question 3

A glass ← ReadAcoustic()

B threshold ← 90

C IF glass >= threshold THEN

D OUTPUT Glass break

E ENDIF

Question 4

A WHILE monitoring = TRUE

B dB ← ReadTemperature()

C IF dB > 85 THEN

D OUTPUT "Noise warning"

E ENDIF

F ENDWHILE

Question 5

A reading ← ReadAcoustic

B IF reading > 70 THEN

C OUTPUT "Loud sound"

D ENDIF

Answer Key

Acoustic sensor

Section A: Quick Questions

B — Sound

A — The level of a sound

A — A sound such as breaking glass or a forced door

A — Acoustic sensor

B — An acoustic sensor can detect that a sound is present

Section B: Match the Pairs

IF soundLevel > 85 THEN → The acoustic sensor reading is compared with a limit to check whether a noise is too loud

IF soundDetected = TRUE THEN → The acoustic sensor reports that a sound is present, for example in a burglar alarm

A noise monitoring system uses an acoustic sensor to measure how loud the sound is → noiseLevel ← ReadAcousticSensor()

A glass-break detector sets off an alarm when its acoustic sensor picks up a loud, sharp sound → IF soundLevel > 90 THEN SoundAlarm()

humidity ← ReadAcousticSensor() → An acoustic sensor detects sound, not humidity, so the data captured is the wrong type

IF soundLevel > 85 THEN LightOn() → The output does not match the purpose of a noise monitor, which should warn about loud sound not switch on a light

Section C: Definitions

acoustic sensor — A sensor that detects sound and measures its level. Used in noise monitoring, burglar alarms and glass-break detection to show how loud a sound is or whether a sound is present.

Section D: Fill in the Blanks

IF soundLevel > 80 THEN
  OUTPUT "Too loud"
ENDIF

IF soundLevel > 80 THEN
  OUTPUT "Noise warning"
ENDIF

alarm ← FALSE
IF soundDetected = TRUE THEN
  alarm ← TRUE

WHILE monitoring = TRUE DO
  soundLevel ← READ_SENSOR(acoustic)
ENDWHILE

limit ← 85
soundLevel ← READ_SENSOR(acoustic)
IF soundLevel > limit THEN

Section E: Spot the Error

B — An IF statement needs THEN after its condition. The line should be IF level > 80 THEN.

C — A burglar alarm should sound when the sound level is above the threshold, not below it. The condition should be sound > 60.

D — Text to be output must be in quotation marks. It should be OUTPUT "Glass break".

B — A noise monitor must read the acoustic sensor, which measures sound level. A temperature sensor cannot measure noise. It should be ReadAcoustic().

A — The function call is missing its brackets. It should be ReadAcoustic() so the sensor reading is returned.