I would like to do some audio programming for a school project, but I'm not sure how a computer processes audio and reconstructs it in a sound card. I've had a signal processing course that covered standard DSP topics but I'm not sure when or how they are applied to acquire, store, and reproduce audio through a sound card. In trying to find a functional explanation I usually see it explained as sampling a time domain signal, storing the samples, and then reproducing audio wave in the time domain by using the sample to represent a voltage at discrete time intervals. But use of the FFT is always mentioned, but I'm not sure how it all fits together. So I have two "theories" about how it's accomplished.(adsbygoogle = window.adsbygoogle || []).push({});

a) A audio signal x(t) is sampled, which represents signal voltage levels at discrete time intervals x[n]. The time domain samples are stored in memory. Then the time domain samples are used to output a voltage signal by setting a voltage level to the value of the sample x[n] at time intervals of the sampling period.

b) A audio signal x(t) is sampled as before. The samples x[n] are then passed to an FFT then the frequency domain values X[k] are stored in memory. Reconstruction is accomplished by oscillators in the sound card which each oscillate at a discrete frequency (for time intervals of the sampling period) at the magnitude indicated by the value of the sample X[k].

Or, in other words. When you give data to a sound card to output audio, is your data a time domain representation of the signal where each successive data value represents the magnitude of the wave at a time interval x[n], or does the data you give sound card represent discrete frequency values X[k] at time intervals.

I know this question is verbose, but I think the easiest way for me to gain understanding is to explain what I think is going on as I understand, and let somebody else tell me where I'm looking at this wrong. I hope someone can straighten me out on this.

Thanks.

**Physics Forums - The Fusion of Science and Community**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Digital audio from a sound card

Loading...

Similar Threads - Digital audio sound | Date |
---|---|

Where can I find a digital counter for turns? | Oct 27, 2016 |

What is digital bandwidth finder | May 16, 2016 |

Is a sine signal a continous signal (analog signal) or a digital signal (discrete signal)? | Oct 13, 2014 |

Digital scale > laptop data transfer help? | Sep 28, 2014 |

Useful Representations of Log Audio Frequency Spectrum | Jun 20, 2013 |

**Physics Forums - The Fusion of Science and Community**