Sound questions and answers
Q1. Explain what a microphone does.
A1. When you speak or play music into a microphone, the microphone takes the sound waves and converts them into a voltage. As the sound waves vary, so the voltage varies
Q2. Explain what a sound card does in relation to recording sound.
A2. The microphone is connected to a computer's sound card. The sound card samples the microphone's voltage at intervals. How many times it does this in a second is known as the 'sample rate'. Each time the voltage is sampled, it is converted into a binary number by the sound card's Analogue to Digital Converter (ADC) and stored. The collection of samples creates a sound file.
Q3. Explain what a sound card does in relation to playing a sound file.
A3. To play back a sound file through some speakers, the sound file is passed back to the sound card, into which the speakers are connected. The Digital to Analogue Converter (DAC) on the sound card takes the digital signals that make up the sound file and converts them back into analogue signals. They are then passed out to the speakers and the sound is played.
Q4. Explain what is meant by the term ‘sample rate’.
A4. How many times the sound card samples a microphone’s voltage in a second.
Q5. What is used to convert an analogue signal into a digital one?
A5. An ADC.
Q6. What is used to convert a digital signal into an analogue one?
A6. A DAC.
Q7. What is meant by the 'sample interval'?
A7. This is the time between samples.
Q8. If you decrease the sample interval, what happens to the file size?
A8. It increases. You are taking more readings in any particular time so the file size increases.
Q9. If you decrease the sample interval, what happens to the quality of the recording?
A9. It increases. You have more samples so can more closely match the original recording.
Q10. If you increase the sample interval, what happens to the quality of the recording?
A10. It decreases. You have less samples so can less closely match the original recording.