Sounds

Humans can hear sound frequencies normally in this range:

"approximately 20 to 20,000 hertz"

As we get older we hear less of the higher frequencies .....more so if you are male!

I wonder why headphones are made that start from 5Herts to 35Khz ?

we hear sounds all the time. Sounds has been recorded for many years. Many formats, from the the mechanical phonograph cylinder, invented by Thomas Edison in 1877 to the digital technology used to-day has been used to capture a great variety of sounds. Some examples...vinyl discs, magnetic tape and compact discs. With the ability to convert analouge audio to digital equivalent storing the music has become easier and many file formats are used to store the result.

MP3 has been the portable media format commonly used on most portable devices and mobile phones.

MPEG Audio Layer III (MP3). Compression is greatly used in mp3 tracks reducing the content by a great amount.

This does affect the sound quality to some degree.

Waveform Audio File Format.This standard is used for storing an audio bitstream on a computer. Data is uncompressed audio stored in a digital format. Audio CDs do not use WAV but the data is stored in a 44100 Hz, 16-bit stereo format encoded in PCM.

Pulse-code modulation (PCM) : A PCM stream is a digital representation of an analog signal used in a multitude of devices for example telephone systems, CDs , BLU-RAY discs and DVDs.

Lossless Audio:

FLAC stands for Free Lossless Audio Codec. Very similar to MP3 but there is no loss in the compression so lossless, meaning that audio is compressed without any loss in quality.

Apple Lossless Audio Codec, ALAC a type of audio compression created by Apple Inc.

Sampling Bit Rate:

If a sample of an audio note is taken and measured on a 8 bit scale it can have a value of 0-63 low resolution quality.

With 12 bit the note can have a value of 0-1024 (used by early recording equipment).

16 bit Audio CD quality , decent quality with 65,536 possible levels.

24 bit audio- high quality - with 16,777,216 possible levels

A CD-quality stereo stream uses two (channels) x 16 (bits per sample) x 44,100 (samples per second) = 1411.2 Kb/s