audio resources

Basics terminology

Bit Rate

In simple terms bit rate represent the resolution. The higher the bit rate, the better the quality of sound. It is a similar concept to the resolution on your computer monitor - you can choose to set your monitor at 8 bit, 16 bit or 24 bit and as you increase the bit the more colors it can display on your monitor. In sound, the higher resolution translates as a better representation of the waveform, resulting in better sound. So a 16 bit recording has better sound than a 8 bit however because it is higher quality it is a larger file.

Sampling Rate

Sampling rate is all about how many times the wave pattern of the sound is sampled per second. CD quality music is normally recorded at 44.1 kHz (= 44,100 hz); this means that for or every second of sound, the digital recording stores 44,100 "snapshots", or samples, of the original waveform. If the recording is in stereo then the digital recording will actually store double that number of samples, or 88,200 samples per second for a sampling rate of 44100. The more times the original wave is sampled per cycle (ie the faster the sampling rate) the more faithful the digital recording will be to original sound.

Mobile devices that record sound normally have a sampling rate of 8 mHz, 22.05 mHz or 44.1 mHz. The higher the sampling rate the better the recording but the larger the file size.

So how does that relate to recording sound for a podcast: the better the quality of sound recorded initially the superior the sound of the podcast will be. If your initial sound recording is poor you can't improve it. WARNING: The type of recorder is only part of the story, if you want good sound you also need to consider attaching a good microphone to your recording device.

File Size

Approximate file sizes of sound recorded for one minute at the different rates:

Sound Quality	Stereo 16 Bit	Stereo 8 bit	Mono 16 bit	Mono 8 bit
CD (44.1 kHz)	10 MB	5 MB	5MB	2.5 MB
FM Radio (22.05 kHz)	5 MB	2.5 MB	2.5 MB	1.25 MB
AM Radio (8 kHz)	1.8 MB	900 kB	900 kB	450 kB

File Format

Just to confuse the issue sound is also recorded in different file formats. The most common recording formats are wav and mp3. Wav is standard Windows digital audio whereas mp3 is a compressed audio format (compressed means that the sound has been made smaller the more compression the poorer the sound quality but the smaller the size). Normally when we podcast sound we upload as a mp3 file

Confused

To understand more and get a better idea of the context i got what I think is a good audio resource

http://aquaculturepda.wikispaces.com/ipods3