Emphasis
Filtering applied to an audio signal before storage or transmission to improve the signal-to-noise ratio at high frequencies.


Encoder
An embodiment of an encoding process.


Entropy
Entropy, the average amount of information represented by a symbol in a message, is a function of the model used to produce that message and can be reduced by increasing the complexity of the model so that it better reflects the actual distribution of source symbols in the original message.
    Entropy is a measure of the information contained in message, it's the lower bound for compression.


Entropy coding
Variable length lossless coding of the digital representation of a signal to reduce statistical redundancy.


EFM (Eight to Fourteen Modulation)
EFM is a storing scheme developed by Philips and Sony. It provides redondance of data in order to increase reliability. It is used in DVD.