Nathan Grisier Emmanuel Villarruel Praja Katel Jackson Lund

 Sound Interference and Overtones  Amplifiers/Speakers  Acoustic Architecture  Line arrays

 Sound  Produced from vibrations  Loud enough for everyone to hear  Interference  Weather  Destructive interference  Opposite vibrations

 Other frequencies besides the fundamental that exist in musical instruments  Different musical instruments produce different overtones  Create individual sound of instruments  Most instruments would sound the same if it weren't for overtones

 An electronic amplifier that amplifies low- power audio signals to a level suitable for driving loud speakers is the final stage a typical audio playback chain

 Lee de Forest  Invented the first audio amplifier, 1909  Triode Vacuum tube  AM radio  Matti Otala  Discovered Transient Intermodulation Distortion (TIM)

 Sound waves are perceived by the microphone and are then converted into corresponding electrical voltage varying in frequency and amplitude according to pressure of the sound vibrations  Many amplifiers have provision for receiving the signals from several microphones or other sources, combining them, and amplifying the combined program to the power required for the audience to hear easily

 Roman Era  Vitruvius  Wrote “De Architectura”, known today as “The Ten Books on Architecture”.  Beginning of acoustic architecture  Renaissance  Opera houses  Concert halls  Churches  18 th Century  Experimentation  20 th Century  Wallace Sabin

 A = Absorb  Reduces reverberation  Porous absorbing materials  drapes, carpets, ceiling tiles, etc.  B = Block  Prevents sound waves from continuing on their path  panels, walls, floors, ceilings and noise barriers.  C = Cover-up  sound masking  white or pink noise

 Regulating sound levels  To much noise can be a health hazard, so rules have been set in place that engineers have to be aware of when building a venue  Noise barriers  Walls that are placed around the venue to try and prevent the sound from escaping to residential areas  Buffer zones  Place commercial/industrial buildings around the venue rather than residential.

 Why and what are line arrays?  Line arrays are a group of speakers, usually or as much as 20, stacked on top of each other and hung at a diagonal angle.  Time delay  Sound is a directional waveform and travels around 1000 ft/sec. causing time the time delay to differentiate between the front row to the middle to the very back row of the venue or concert field.  The job of the sound engineer or technician is to balance

 In order to reach the everyone line arrays are strategically placed on the stage and throughout the audience.  The sound output to the middle row line arrays are put on a time delay  In order to find the right time delay, measure 1 milsec/ft from the middle row

 next time one of you attend a concert, whether inside or outside, you will be able to understand why the speakers and the music sounds clear and full of life