User:Sjohns:project 2

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Audio Project

Using 28.8Kbps for dial up downloading speed and 1.5Mbps for DSL downloading speed.

Uncompressed vs. Compressed

Format

File size

Download time (Dialup)

Download time(DSL)

Link to Download

Using Audacity I produced a 44,100hz and 32 bits[WAV] format file which is

31.31 MB

31 Min 59 Sec

55 Sec

Click here to download this version

Using Audacity I produced a MP3 format file which is:

1.85 MB

8 Min 58 Sec

0 Min 10 Sec

Click here to download the MP3 version


Quantization and Sampling Rates

CD quality audios are usually sampled at 44,100 samples per second with a 2 byte quantization level.

Format

File size

Dialup download time

ADSL download time

Download

With Audacity, here is a [WAV] format file which has a sample rate of 44100 samples per second and a quantization level of 32 bits:

31.31 MB

2 Hours 31 Min 59 Sec

55 Sec

Click here to download this version

With Audacity, here is a [WAV] format file which has a sample rate of 44100 samples per second and a quantization level of 16 bits:

15.65 MB

1 Hour 15 Min 58 Sec

27 Sec

Click here to download this version

With Audacity, here is a [WAV] format file which has a sample rate of 8000 samples per second and a quantization level of 16 bits:

16.45 MB

1 Hour 19 Min 51 Sec

1 Min 31 Sec

Click here to download this version


Reflection Questions

  • What's the difference between WAV format and MP3 format and how different formats affect downloading time ? (Hint: file size; compression)
Answer: The WAV format is uncompressed and lossless. However, the MP3 format is compressed and lossy. The different formats greatly affect downloading time. The MP3 format has a smaller file size and faster downloading time compared to the WAV format.
  • Do you know any other audio format? Please list at least two.
Answer: WMA, RA and AIFF
  • How sampling and quantization affect audio quality?
Answer: : Both sampling and quantization affect the audio quality in the same way. If there are fewer quantization levels or a smaller sampling rate, the quality of the sound decreases. In addition, the file size will be smaller if either the sampling rate or quantization levels are decreased.


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