The Cocktail-Party-Effect

Deutsche Fassung

Extraction of one Sound Source

The term Cocktail-Party-Effect describes the ability of the human auditory system to focus on the signals of a sound source when multiple sound sources are simultaneously active. Thus, at a cocktail party where many people speak simultaneously, a listener is able to concentrate on only one speaker and disregard the other speakers.

Comparing the personal listening experience in "cocktail party" situations with microphone recordings of the same situation, so the microphone recordings appear much more strongly disturbed by noise sources (other speakers) than your hearing. Due to the Cocktail-Party-Effect the human auditory system can achieve an enhancement of the signal-to-noise-ratio of 9..15 dB. That is, a human listener can reduce the perceived loudness of interfering sound sources by a factor of 2..3.

Reduction of Echo and Reverberation

At the hearing in enclosed rooms a listener is capable to suppress distracting reflections and reverberation considerably. Comparing the personal listening experience in a room with microphone recordings from the same room, microphone recordings sound much more reverberant.

Inside enclosed rooms the sound of a sound source is reflected at the walls again and again. A wall reflection has the same effect on the sound field as the introduction of a corresponding "mirror sound source" behind the wall. Analogous to the wall reflections, these "mirror sound sources" would then be distributed over all directions.
A Cocktail-Party-Processor, which is able to suppress sound from directions, which are different to the direction of a desired sound source, can also be used to reduce the effect of echoes and reverberation. Since all those "mirror sound sources" are suppressed, whose directions do not match to the direction of desired sound source, the total number of perceived mirror sound sources is reduced. As a result, the perceived sound will contain less echoe and reverberation.

Separation of Sound Sources

The human auditory system uses several methods to separate a desired sound source from interfering sound sources.

Types of Cocktail-Party-Processors

There are several approaches to extract the signals of a desired sound source from a mixture of sound signals. Depending on the number of used sound receivers, Cocktail-Party-Processors can be classified as follows:

Properties of Cocktail-Party-Processors

The properties of a Cocktail-Party-Processor depend on its type.

Combining Cocktail-Party-Processors

To achieve good results for broadband signals, it is useful to combine different types of cocktail-party processors, such as:


Depending on the type of Cocktail-Party-Processor, different types of algorithms are used to extract the signal of the desired sound source.

The evaluation algorithms for monaural and binaural Cocktail-Party-Processors can also be classified to at least two types: