Editing Sound reinforcement system (section)

==Applications==
Sound reinforcement systems are used in a broad range of different settings, each of which poses different challenges.

===Rental systems===
[[File:Sound System.jpg|thumb|right|200px|Staff set up sound system speaker cabinets for an outdoor event.]]
Audio-visual rental systems have to be able to withstand heavy use and even abuse from renters. For this reason, rental companies tend to own speaker cabinets that are heavily braced and protected with steel corners, and electronic equipment such as power amplifiers or effects are often mounted into protective road cases. Rental companies also tend to select gear that have electronic protection features, such as speaker-protection circuitry and amplifier limiters.

Rental systems for non-professionals need to be easy to use and set up and they must be easy to repair and maintain for the renting company. From this perspective, speaker cabinets need to have easy-to-access horns, speakers, and crossover circuitry, so that repairs or replacements can be made.

Many touring acts and large venue corporate events will rent large sound reinforcement systems that typically include one or more audio engineers on staff with the renting company. In the case of rental systems for tours, there are typically several audio engineers and technicians from the rental company that tour with the band to set up and calibrate the equipment. The individual that mixes the band is often selected and provided by the band, as they are familiar with the various aspects of the show and understand how the band wants the show to sound.

===Live music clubs and dance events===
[[File:FOH Pete Keppler with digidesign VENUE Profile live digital mixer and Genelec monitoring.jpg|thumb|right|200px|A front-of-house sound engineer with a Digidesign D-Show Profile live digital mixer and a computer monitor.]]

Setting up sound reinforcement for live music clubs and dance events often poses unique challenges, because there is such a large variety of venues that are used as clubs, ranging from former [[warehouses]] or music theaters to small restaurants or basement pubs with concrete walls. Dance events may be held in huge warehouses, aircraft hangars or outdoor spaces. In some cases, clubs are housed in multi-story venues with balconies or in L-shaped rooms, which makes it hard to get a consistent sound for all audience members. The solution is to use fill-in speakers to obtain good coverage, using a delay to ensure that the audience does not hear the same reinforced sound at different times.

The number of [[subwoofer]] speaker cabinets and power amplifiers dedicated to low-frequency sounds used in a club depends on the type of club, the genres of music played there, and the size of the venue. A small [[coffeehouse]] where traditional folk, bluegrass or jazz groups are the main performers may have no subwoofers, and instead rely on the full-range main PA speakers to reproduce bass sounds. On the other hand, a club where [[hard rock]] or [[heavy metal music]] bands play or a [[nightclub]] where [[DJ]]s play [[dance music]] may have multiple large subwoofers, as these genres and music styles typically use powerful, deep bass sound.

[[File:Groovy 2007 IMG 8290 (1310587792).jpg|thumb|left|200px|A DJ gets his decks ready as the speaker cabinets are set up and readied for a dance event.]]

A challenge with designing sound systems for clubs is that the sound system may need to be used for both prerecorded music played by [[DJ]]s and live music. A club system designed for DJs needs a [[DJ mixer]] and space for [[record player]]s. In contrast, a live music club needs a mixing board designed for live sound, an onstage monitor system, and a multicore snake cable running from the stage to the mixer. Clubs that feature both types of shows may face challenges providing the desired equipment and set-up for both uses. Clubs can be a hostile environment for sound gear, in that the air may be hot, humid, and smoky. In some clubs, keeping power amplifiers cool may be a challenge.

===Houses of worship===
[[File:Iglesia Los Olivos.jpeg|thumb|right|200px|The Iglesia Los Olivos church. P.A. speakers are mounted on the ceiling to reproduce the speech of the priest.]]
Churches and similar houses of worship often pose design challenges. Speakers may need to be unobtrusive to blend in with antique woodwork and stonework. In some cases, audio designers have designed custom-painted speaker cabinets. Some facilities, such as [[sanctuaries]] or chapels are long rooms with low ceilings and additional fill-in speakers are needed throughout the room to give good coverage. Once installed, church systems are often operated by amateur volunteers from the congregation, which means that they must be easy to operate and troubleshoot. To this end, some mixing consoles designed for houses of worship have automatic mixers, which turn down unused channels to reduce noise, and automatic feedback elimination circuits which detect and notch out frequencies that are feeding back. These features may also be available in multi-function consoles used in convention facilities and multi-purpose venues.

===Touring systems===
[[File:Meyer DSC 5476-01EC.jpg|thumb|right|200px|A Meyer line array of speaker cabinets is moved into position at an outdoor concert.]]
Touring sound systems are available in many different sizes and shapes as they have to be powerful and versatile enough to cover many different halls and venues. Touring systems range from mid-sized systems for bands playing [[nightclub]] and other mid-sized venues to large systems for groups playing [[stadium]]s, arenas and [[outdoor festival]]s. Tour sound systems are often designed with substantial redundancy features, so that in the event of equipment failure or amplifier overheating, the system will continue to function. Touring systems for bands performing for crowds of a few thousand people and up are typically set up and operated by a team of technicians and engineers who travel with the performers to every show.

Mainstream bands that are going to perform in mid- to large-sized venues during their tour schedule one to two weeks of technical rehearsal with the entire concert system and production staff, including audio engineers, at hand. This allows the audio and lighting engineers to become familiar with the show and establish presets on their digital equipment (e.g., digital mixers) for each part of the show, if needed. Many modern musical groups work with their [[front of house]] and monitor mixing engineers during this time to establish what their general idea is of how the show and mix should sound, both for themselves on stage and for the audience.

This often involves programming different effects and signal processing for use on specific songs, to make the songs sound somewhat similar to the studio versions. To manage a show with a lot of effects changes, the mixing engineers for the show often choose to use a [[digital mixing console]] so that they can save and automatically recall these many settings in between each song. This time is also used by the system technicians to get familiar with the specific combination of gear that is going to be used on the tour and how it acoustically responds during the show. These technicians remain busy during the show, making sure the SR system is operating properly and that the system is tuned correctly, as the acoustic response of a room or venue will respond differently throughout the day depending on the temperature, humidity, and number of people in the room or space.

===Live theater===
Sound for live theater, operatic theater, and other dramatic applications may pose problems similar to those of churches; theaters may be in heritage buildings where speakers and wiring is required to blend in with the architecture. The need for clear [[Sightline (architecture)|sightlines]] may make the use of regular speaker cabinets unacceptable; instead, slim, low-profile speakers are often used instead.

In live theater and drama, performers move around onstage, which means that [[wireless microphone]]s may be necessary. Some of the higher-budget theater shows and musicals are mixed in surround sound live, often with the show's sound operator triggering sound effects that are being mixed with music and dialogue by the show's mixing engineer. These systems are usually much more extensive to design, typically involving separate sets of speakers for different zones in the theater.

===Classical music and opera===
[[File:20070919 Pritzker Pavilion speakers.JPG|left|thumb|the first permanent LARES outdoor speakers at a concert venue named [[Jay Pritzker Pavilion]]]]

A subtle type of sound reinforcement called [[acoustic enhancement]] is used in some concert halls where classical music such as symphonies and opera is performed. Acoustic enhancement systems add more sound to the hall and prevent ''dead spots'' in the audience seating area by "...augment[ing] a hall's intrinsic acoustic characteristics." The systems use "...an array of microphones connected to a computer [which is] connected to an array of loudspeakers." However, as concertgoers have become aware of the use of these systems, debates have arisen, because "...purists maintain that the natural acoustic sound of [Classical] voices [or] instruments in a given hall should not be altered."<ref>[http://harada-sound.com/sound/handbook/intro2.html Why do you need a Sound System?]</ref>

Kai Harada's article ''Opera's Dirty Little Secret'' states that opera houses have begun using electronic acoustic enhancement systems "...to compensate for flaws in a venue's acoustical architecture." Despite the uproar that has arisen amongst operagoers, Harada points out that none of the opera houses using acoustic enhancement systems "...use traditional, Broadway-style sound reinforcement, in which most if not all singers are equipped with radio microphones mixed to a series of unsightly loudspeakers scattered throughout the theatre." Instead, most opera houses use the sound reinforcement system for acoustic enhancement, and for subtle boosting of offstage voices, onstage dialogue, and sound effects (e.g., church bells in [[Tosca]] or thunder in Wagnerian operas).<ref>LiveDesignOnline.com. Kai Harada, Mar 1, 2001. [http://livedesignonline.com/mag/show_business_operas_dirty_little/ ''Opera's Dirty Little Secret''.] Retrieved on March 24, 2009.</ref>

These systems use microphones, computer processing "with delay, phase, and frequency-response changes", and then send the signal "...&nbsp;to a large number of loudspeakers placed in extremities of the performance venue." Another acoustic enhancement system, [[VRAS]] 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.<ref>Entertainment Design, Mar 1, 2001   {{cite web |url=http://industryclick.com/magazinearticle.asp?releaseid=5643&magazinearticleid=66853&siteid=15&magazineid=138 |title=PRIMEDIA Business Magazines & Media Inc |access-date=2007-10-25 |url-status=dead |archive-url=https://web.archive.org/web/20131031082324/http://industryclick.com/magazinearticle.asp?releaseid=5643&magazinearticleid=66853&siteid=15&magazineid=138 |archive-date=2013-10-31 }}</ref>

===Lecture halls and conference rooms===
Lecture halls and conference rooms pose the challenge of reproducing speech clearly in 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.

Another challenge with doing live sound for individuals who are speaking at a conference is that, in comparison with [[Lead singer|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]].

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 that are not being spoken into, to reduce unwanted background noise and reduce the likelihood of feedback.

===Sports sound systems===
[[File:Haut parleur Nou Camp.JPG|thumb|right|200px|A speaker array mounted in the rafters in a camp sports facility.]]
Systems for sports facilities often have to deal with substantial echo, which can make speech unintelligible. Sports and recreational sound systems often face environmental challenges as well, such as the need for weather-proof outdoor speakers in outdoor stadiums and [[humidity]]- and splash-resistant speakers in swimming pools. Another challenge with sports sound reinforcement setups is that in many arenas and stadiums, the spectators are on all four sides of the playing field. This requires 360-degree sound coverage. This is very different from the norm with music festivals and music halls, where the musicians are on stage and the audience is seated in front of the stage.