---
title: Ascertain the principle by which noise-cancelling headphones reduce… — Bangs and loud sounds: firecrackers an… · tree and pragmatics
description: Ascertain the principle by which noise-cancelling headphones reduce ambient noise. Exam question 4 of lesson 19 «Bangs and loud sounds: firecrackers and ears» of the physics course of Mova's primary school, with the dependency tree and pragmatics of the question and of each option; Mova's choice was
---

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# Exam question 4 · Bangs and loud sounds: firecrackers and ears

<!-- .ven lang=en -->
Ascertain the principle by which noise-cancelling headphones reduce ambient noise.

<!-- .vintro -->
**Mova's choice:** option 1 · **The right answer:** option 1 · right ✓ · **Who acts:** you, cancelling headphones · **What happens:** ascertain, reduce · **To what, where:** principle, ambient noise

<!-- .vabout -->
This is exam question 4 of lesson 19 «Bangs and loud sounds: firecrackers and ears» of the physics course of Mova's primary school, asked in stiff, formal language. The page gives the question's syntax tree — a dependency tree in the style of Universal Dependencies — and its pragmatics clause by clause, then the 4 options as the student saw them, each with its tree and pragmatics. Every text is parsed by Mova itself. How the student answered it, with the score of every option and why: [the test at school](https://md.mova.elamur.ai/free/en/school-run/physics/19-bangs-and-loud-sounds-firecrackers-and-ears/#e4).

## The question {#question}

```conllu
# sent_id = question:physics:19-bangs-and-loud-sounds-firecrackers-and-ears:e4:1
# text = Ascertain the principle by which noise-cancelling headphones reduce ambient noise.
1	Ascertain	ascertain	VERB	VB	Mood=Imp|VerbForm=Fin	0	root	_	_
2	the	the	DET	DT	Definite=Def|PronType=Art	3	det	_	_
3	principle	principle	NOUN	NN	Number=Sing	1	obj	_	_
4	by	by	ADP	IN	_	5	case	_	_
5	which	which	PRON	WDT	PronType=Rel	10	obl	_	_
6	noise	noise	NOUN	NN	Number=Sing	8	compound	_	SpaceAfter=No
7	-	-	PUNCT	HYPH	_	6	punct	_	SpaceAfter=No
8	cancelling	cancelling	NOUN	NN	Number=Sing	9	compound	_	_
9	headphones	headphone	NOUN	NNS	Number=Plur	10	nsubj	_	_
10	reduce	reduce	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	3	acl:relcl	_	_
11	ambient	ambient	ADJ	JJ	Degree=Pos	12	amod	_	_
12	noise	noise	NOUN	NN	Number=Sing	10	obj	_	SpaceAfter=No
13	.	.	PUNCT	.	_	1	punct	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **ascertain** | imperative | you *not said here* | the principle |  |  |  |  | vn discover-84 «NP V NP»: agent=Agent principle=Topic |
| 2 | **reduce** | present | cancelling headphones | ambient noise |  |  |  | by the principle | vn limit-76 «NP V NP»: agent=Causer noise=Patient |

<!-- .note -->
One row per clause the reader finds. «not said here»: a role filled from the clause above. «roles by»: a VerbNet class and frame when one fits the verb, else the reader's rules on the tree.

## The options {#options}

### Option 1 · ← Mova's choice · ✓ the right answer {#o1}

<!-- .ven lang=en -->
A wave opposite to the incident noise is generated so that the two cancel

```conllu
# sent_id = question:physics:19-bangs-and-loud-sounds-firecrackers-and-ears:e4:o1:1
# text = A wave opposite to the incident noise is generated so that the two cancel
1	A	a	DET	DT	Definite=Ind|PronType=Art	3	det	_	_
2	wave	wave	NOUN	NN	Number=Sing	3	compound	_	_
3	opposite	opposite	NOUN	NN	Number=Sing	9	nsubj:pass	_	_
4	to	to	ADP	IN	_	7	case	_	_
5	the	the	DET	DT	Definite=Def|PronType=Art	7	det	_	_
6	incident	incident	NOUN	NN	Number=Sing	7	compound	_	_
7	noise	noise	NOUN	NN	Number=Sing	3	nmod	_	_
8	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	9	aux:pass	_	_
9	generated	generate	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
10	so	so	SCONJ	IN	_	14	case	_	_
11	that	that	SCONJ	IN	_	10	fixed	_	_
12	the	the	DET	DT	Definite=Def|PronType=Art	14	det	_	_
13	two	two	NUM	CD	NumForm=Word|NumType=Card	14	nummod	_	_
14	cancel	cancel	NOUN	NN	Number=Sing	9	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **generate** | present · passive |  | a wave opposite to the incident noise |  |  |  | so the two cancel | vn birth-28.2-1 «NP V NP»: subject=Patient |

### Option 2 {#o2}

<!-- .ven lang=en -->
The noise is absorbed by foam exclusively

```conllu
# sent_id = question:physics:19-bangs-and-loud-sounds-firecrackers-and-ears:e4:o2:1
# text = The noise is absorbed by foam exclusively
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	noise	noise	NOUN	NN	Number=Sing	4	nsubj	_	_
3	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	aux:pass	_	_
4	absorbed	absorb	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
5	by	by	ADP	IN	_	6	case	_	_
6	foam	foam	NOUN	NN	Number=Sing	4	obl	_	_
7	exclusively	exclusively	ADV	RB	_	4	advmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **absorb** | present · passive | foam | the noise |  |  |  | exclusively *property* | vn absorb-39.8 «NP V NP»: agent=Goal subject=Theme |

### Option 3 {#o3}

<!-- .ven lang=en -->
The noise is masked by music of greater volume

```conllu
# sent_id = question:physics:19-bangs-and-loud-sounds-firecrackers-and-ears:e4:o3:1
# text = The noise is masked by music of greater volume
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	noise	noise	NOUN	NN	Number=Sing	4	nsubj	_	_
3	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	aux:pass	_	_
4	masked	mask	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
5	by	by	ADP	IN	_	6	case	_	_
6	music	music	NOUN	NN	Number=Sing	4	obl	_	_
7	of	of	ADP	IN	_	9	case	_	_
8	greater	great	ADJ	JJR	Degree=Cmp	9	amod	_	_
9	volume	volume	NOUN	NN	Number=Sing	6	nmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **mask** | present · passive | music of greater volume | the noise |  |  |  |  | vn fill-9.8 «NP V NP»: agent=Theme subject=Destination |

### Option 4 {#o4}

<!-- .ven lang=en -->
The noise is converted into light

```conllu
# sent_id = question:physics:19-bangs-and-loud-sounds-firecrackers-and-ears:e4:o4:1
# text = The noise is converted into light
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	_	_
2	noise	noise	NOUN	NN	Number=Sing	4	nsubj	_	_
3	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	aux:pass	_	_
4	converted	convert	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	_
5	into	into	ADP	IN	_	6	case	_	_
6	light	light	NOUN	NN	Number=Sing	4	obl	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **convert** | present · passive |  | the noise |  |  |  | into light *result* | vn turn-26.6.1-1 «NP V NP.patient PP.result»: subject=Patient into light=Result |

<!-- div src -->

**Text:** the tests of Mova's primary school, written for Mova (`world/data/school/`), as the course runner gave them to the student. **Trees:** Mova's own parse — the `en` model on the CPU, when the site is built — not checked by a teacher; they may be wrong. **Frames:** Mova's frames reader (`prag`), each text read on its own. Elamur Cosmic License.

<!-- /div -->

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- ← previous: [Bangs and loud sounds: firecrackers an…, exam 3](https://md.mova.elamur.ai/free/en/corpora/questions/physics/19-bangs-and-loud-sounds-firecrackers-and-ears/e3/)
- next →: [Light and shadows, test 1](https://md.mova.elamur.ai/free/en/corpora/questions/physics/20-light-and-shadows/t1/)
- ↑ back to [Bangs and loud sounds: firecrackers and ears](https://md.mova.elamur.ai/free/en/corpora/questions/physics/19-bangs-and-loud-sounds-firecrackers-and-ears/)