---
title: "Short note: Noise and its effects"
subject: "Building Technology"
chapter: 1
key: "semester_6/building_technology:short-noise-effects"
source: https://www.bctengineer.com/q/semester_6/building_technology/short-noise-effects
site: BCT Engineering
---

# Short note: Noise and its effects

Building Technology · Chapter 1: Functional Requirements of Buildings

- Asked in: 2062 Baisakh (old course), 4 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/short-noise-effects
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-1

## Question

Write a short note on noise and its effects.

## Short answer

Noise is unwanted sound measured in decibels, with common sources like traffic, industry, and loudspeakers. Effects include hearing loss above 85 dB, high blood pressure, stress, sleep disturbance, reduced efficiency, speech interference, structural damage, and lower property value. Control uses barriers, insulation, absorption, silencers, and legal limits.

## Answer

**Noise** is unwanted or disturbing sound. It is measured in decibels (dB); for example, a quiet room is about 30 dB, normal talk 60 dB, heavy traffic 80 to 90 dB, and a jet engine 120 dB or more.

#### Sources
Road, rail and air traffic; industry and construction machines; generators; loudspeakers and crowds; neighbours and domestic appliances.

#### Effects of noise
1. **Hearing loss**: Temporary or permanent damage from long exposure over about 85 dB.
2. **Physiological effects**: High blood pressure, rapid heart rate, tiredness and headache.
3. **Psychological effects**: Stress, irritation, anger, anxiety and loss of concentration.
4. **Sleep disturbance**: Poor sleep, less rest.
5. **Reduced efficiency** at work and study, and mistakes or accidents.
6. **Speech interference**: Poor communication.
7. **Social and economic effects**: Reduced property value and loss of privacy.
8. **Structural effects**: Intense noise and vibration may crack glass and weak parts.

#### Control
Site planning with distance and barriers, sound-insulated construction, absorption in rooms, silencers, and law limits on noise. The Nepal Environment Protection Rules set standards for noise levels.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Noise is:
   A. Any sound
   B. Unwanted or disturbing sound
   C. Only loud sound
   D. Ultrasound
   Answer: B. Noise is unwanted sound, measured in dB. (Key point: Definition)

2. Long exposure above about what level can damage hearing?
   A. 30 dB
   B. 85 dB
   C. 50 dB
   D. 10 dB
   Answer: B. Over about 85 dB gives hearing loss. (Key point: Hearing loss)

3. Psychological effects include:
   A. Stress, irritation, loss of concentration
   B. Cracked glass
   C. High pulse only
   D. Deafness
   Answer: A. Stress and anxiety are psychological. (Key point: Psychological)

4. Noise control includes:
   A. Site planning, insulation, absorption, silencers, legal limits
   B. Louder machines
   C. Removing walls
   D. Hard surfaces
   Answer: A. Combine planning, construction and regulation. (Key point: Control)

## Related in other subjects

- [Noise vs interference; minimizing effects; need for modulation](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Anoise-interference-minimize-modulation-need) — Communication Systems, chapter 1
- [Typical noise levels and effects of noise](https://www.bctengineer.com/question.md?key=semester_7%2Fenvironment_and_pollution_control%3Anoise-levels-places-effects) — Environment and Pollution Control, chapter 6
- [Analog vs digital source; atmospheric noise](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aanalog-vs-digital-source-atmospheric-noise) — Communication Systems, chapter 1
- [Noise, interference, distortion; thermal and high frequency noise](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Anoise-effects-thermal-hf) — Communication Systems, chapter 1