<P> Acoustic enhancement systems include LARES (Lexicon Acoustic Reinforcement and Enhancement System) and SIAP, the System for Improved Acoustic Performance . These systems use microphones, computer processing "with delay, phase, and frequency - response changes", and then send the signal "...to a large number of loudspeakers placed in extremities of the performance venue ." Another acoustic enhancement system, VRAS (Variable Room Acoustics System) uses "...different algorithms based on microphones placed around the room ." The Deutsche Staatsoper in Berlin and the Hummingbird Centre in Toronto use a LARES system . The Ahmanson Theatre in Los Angeles, the Royal National Theatre in London, and the Vivian Beaumont Theater in New York City use the SIAP system . </P> <P> Lecture halls and conference rooms pose the challenge of reproducing speech clearly to a large hall, which may have reflective, echo - producing surfaces . One issue with reproducing speech is that the microphone used to pick up the sound of an individual's voice may also pick up unwanted sounds, such as the rustling of papers on a podium . A more tightly directional microphone may help to reduce unwanted background noises . </P> <P> Another challenge with doing live sound for individuals who are speaking at a conference is that, in comparison with professional singers, individuals who are invited to speak at a forum may not be familiar with how microphones work . Some individuals may accidentally point the microphone towards a speaker or monitor speaker, which may cause audio feedback "howls". In some cases, when an individual who is speaking does not speak enough directly into the microphone, the audio engineer may ask the individual to wear a lavaliere microphone, which can be clipped onto a lapel . </P> <P> In some conferences, sound engineers have to provide microphones for a large number of people who are speaking, in the case of a panel conference or debate . In some cases, automatic mixers are used to control the levels of the microphones, and turn off the channels for microphones which are not being spoken into, to reduce unwanted background noise and reduce the likelihood of feedback . </P>

Music system in store perhaps about last in range