UPSC Prelims 2006 Q86: Science & Technology – Computer & Information Technology
What does the term ‘Dolby B’, or ‘Dolby C’ printed on tape recorders and other sound
systems refer to?
- (a) Frequency modulated system
- (b) Amplitude Modulated system
- (c) Noise reduction circuit
- (d) Both DC and AC power can be used
Answer: (c) Noise reduction circuit
Explanation
Dolby B and Dolby C
| Option | Verdict |
|---|---|
| Frequency modulated system | No |
| Amplitude modulated system | No |
| Noise reduction circuit | Yes — Dolby B and C reduce tape hiss |
| Both DC and AC power can be used | No |
Dolby B and Dolby C are noise reduction systems used on cassette tape recorders to cut the background hiss.
Answer: (c) Noise reduction circuit.
Why each option is right or wrong
- (a) Incorrect. Dolby is not a frequency modulation system.
- (b) Incorrect. Dolby is not an amplitude modulation system.
- (c) CORRECT. Dolby B and C are noise reduction circuits for tape hiss.
- (d) Incorrect. Dolby does not refer to power supply options.
Key point
Dolby B and Dolby C are noise reduction systems used in tape recorders.
Remember
Dolby B and C: noise reduction circuits.
Common mistakes
- Mixing Dolby with FM and AM radio modulation.
- Thinking Dolby marks the power supply.
- Not knowing Dolby systems reduce hiss on cassettes.
Exam tip
Dolby A, B, C, S = noise reduction on tape; Dolby Digital = cinema surround sound.
Sources
- Dolby Laboratories — Dolby noise reduction (Dolby A, B and C types)
- Encyclopaedia Britannica — Dolby