---
title: "Audio hardware"
subject: "Multimedia System"
chapter: 2
key: "semester_8/multimedia_system:audio-hardware"
source: https://www.bctengineer.com/q/semester_8/multimedia_system/audio-hardware
site: BCT Engineering
---

# Audio hardware

Multimedia System · Chapter 2: Sound / Audio System

- Asked in: 2072 Magh, 5 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/multimedia_system/audio-hardware
- Whole chapter: https://www.bctengineer.com/md/semester_8/multimedia_system/chapter-2

## Question

Explain the audio hardware.

## Short answer

Audio hardware converts analogue sound to digital and back using a microphone, sound card with ADC/DAC/DSP/synthesiser, amplifier, speakers, MIDI devices and storage. Quality is judged by sampling rate, bit depth, signal-to-noise ratio and channel count.

## Answer

Audio hardware is the set of devices that capture, convert, process, store and reproduce sound in a computer system. Its job is to convert between the analogue sound world and the digital data the computer uses.

```text
 Sound -> Microphone -> [Sound card: ADC] -> CPU/Memory/Disk
 Sound <- Speaker <- Amplifier <- [Sound card: DAC] <-
```

#### Main parts

1. **Microphone (input transducer).** Changes air pressure variations into a small analogue voltage. Types: dynamic, condenser, and built-in MEMS microphones.
2. **Sound card / audio interface.** The central unit, which has:
   - **ADC:** samples and quantises the analogue input into digital numbers (sampling rate such as 44.1 kHz, 16 or 24 bits).
   - **DAC:** rebuilds the analogue signal from digital data for playback.
   - **DSP chip:** does effects, mixing and some compression.
   - **Synthesiser (FM or wavetable):** plays MIDI music.
   - **Ports:** mic-in, line-in, line-out, speaker out, MIDI/joystick; modern cards use USB or are built into the motherboard.
3. **Amplifier.** Raises the weak DAC signal enough to drive speakers.
4. **Speakers and headphones (output transducers).** Convert the electrical signal back into sound waves; stereo, 5.1 surround sets are used for better effect.
5. **MIDI devices.** Electronic keyboard, synthesiser or drum machine connected by a MIDI cable or USB to send note data.
6. **Storage.** Hard disk, CD, DVD or flash to hold audio files, which are large (about 10 MB per minute for CD quality).

Quality of audio hardware is judged by its sampling rate, bit depth, signal-to-noise ratio and number of channels.

## Check yourself

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

1. What does the ADC on the sound card do?
   A. Samples and quantises the analogue input into digital numbers
   B. Rebuilds the analogue signal from digital data
   C. Amplifies the weak signal
   D. Plays MIDI music
   Answer: A. The ADC samples and quantises the analogue input; the DAC does the reverse. (Key point: ADC function)

2. Why is an amplifier needed after the DAC?
   A. To digitise the sound
   B. To raise the weak DAC signal enough to drive the speakers
   C. To compress the audio
   D. To store the audio
   Answer: B. The DAC output is weak and must be amplified to drive the speakers. (Key point: Amplifier purpose)

3. What does a microphone do as an input transducer?
   A. Converts digital numbers into sound
   B. Stores sound on disk
   C. Changes air pressure variations into a small analogue voltage
   D. Plays MIDI notes
   Answer: C. A microphone converts air pressure variations into a small analogue electrical voltage. (Key point: Microphone role)

4. Which set is used to judge the quality of audio hardware?
   A. Colour depth and resolution
   B. File extension and player
   C. Frame rate and aspect ratio
   D. Sampling rate, bit depth, signal-to-noise ratio and number of channels
   Answer: D. Quality is judged by sampling rate, bit depth, SNR and number of channels. (Key point: Audio quality measures)

## Related in Multimedia System

- [Audio hardware and audio software](https://www.bctengineer.com/question.md?key=semester_8%2Fmultimedia_system%3Aaudio-hardware-software) — Multimedia System, chapter 2