1. A method for automatically detecting sentiments in an audio signal of an interaction held in a call center, comprising: receiving the audio signal from a logging and capturing unit associated with the call center; performing audio analysis on the audio signal to obtain text spoken within the interaction; segmenting the text into context units; extracting a sentiment candidate context unit from the context units; extracting features from the sentiment candidate context unit or from the audio signal; determining in accordance with the features whether the sentiment candidate context unit is valid or erroneous; and determining sentiment polarity and intensity for the sentiment candidate context unit.