2 physics of sound

45 0 0
  • Loading ...
1/45 trang

Thông tin tài liệu

Ngày đăng: 01/12/2016, 23:28

Physics of Sound Part Sound waves How they are generated and travel Sound Waves  Generation and Propagation  Sound wave = changes in pressure caused by vibrating object    Sound needs a medium to “vibrate”   Compression = High pressure Rarefaction = Low pressure Usually air, but could be anything Speed of sound depends upon the medium Air = 1130 ft/sec Water = 5000 ft/sec Steel = 13000 ft/sec Measuring sound waves  Sound waves are longitudinal waves    Vibrating object compresses the air around it Pushes air away leaving an area of low pressure Vibrating object then compresses more air to create a “chain” Measuring methods Cycle  A single push and pull of the vibrating object    One are of compression followed by one area of rarefaction An initial increase in atmospheric pressure from the norm, followed by a drop below the norm and then a return to normal Mathematically displayed by a sine curve   Pressure on Y axis Time on X axis Measuring methods Period (T) and Frequency (f)   Period - The time it takes to create one cycle Frequency - The number of cycles in one second f = T  Measured in Hertz (Hz) or cycles per second Measuring methods Example It takes ¼ sec to create one cycle What is the sound wave’s frequency? f = = cycles per second 25 Measuring methods  Frequency will determine pitch    High frequency = high pitch Low frequency = low pitch Octave – a doubling of halving of the frequency Measuring methods  Human hearing range  Low range between 15 to 30 Hz   With enough power lower than 15 Hz can be felt, but not heard as “sound” High range varies with age and gender    Women - up to 20 kHz Men – between 15 to 18 kHz High frequency range will lower with exposure to high levels of sound and age Tuning  Traditional orchestra would tune First Chair Violin A first     Remaining instruments would tune relative to that A above middle C was tuned to about 420 Hz As halls grew larger it was found to be desirable to tune sharper 1939 A was established to be 440 Hz   Corresponds to the 49th key on a full size piano Tuning is not a science The relative frequency difference is what is important Measuring methods Wavelength  The distance from one area of compression to the next or one area of rarefaction to the next v λ= f l=wave length V = velocity of sound in medium usually 1130 ft/sec f = frequency Interaction of Sound with other Show Elements  Script Identification of motivational cues - sounds listed in the script (cues that actors react to)  Identification of environmental cue opportunities – locations, time of day, season, era,  Identification of emotional cue opportunities – What you want to say about actor, situation  Interaction of Sound with other Show Elements  Acting  Collaborate on what is “heard” on stage - Actors need to understand what sounds are part of the physical environment shared with the set and props Some sounds are there for them to react to (Motivational) Some sounds need to be originated by a performer’s action (ring a bell, turn on a radio, etc ) Monitoring of stage action to off-stage locations  Placement of wireless mics and stage monitoring / fold back  Interaction of Sound with other Show Elements  Costumes   Musicals – wireless mics that need to be accommodated within costumes and hair Scenic Location of on-stage devices (speakers, mics)  Collaboration on scene shifts (needs/opportunities to cover transitions using sound cues – “Functional” sound cues)  Identification of cues that support each other (sound used to reinforce scenic element that would normally make noise (car, train station, rain, etc .)  Interaction of Sound with other Show Elements  Props   “Active” on-stage devices that may be props Lights  Identification of cues that support each other Thunder and lightning, Day time or night time, Lights used to represent outdoors and other items/times that would normally have a recognizable sound associated with it  Identification of transitions where cues should go together Interaction of Sound with other Show Elements  Music direction Vocal reinforcement (micing)  Music reinforcement (micing, direct feeds and mixing)  Vocal/music monitoring for performers and/or band   Choreography Music cues  Reinforcement of foot fall (Mic cues for tap dancing)  Music monitoring for dancers  Interaction of Sound with Other Show Elements  Stage Management Cueing  Monitoring of stage action to booth  Intercom systems  Use of Sound in the Theatre What Audience Hears – Company Hears  Elements that are part of the show  What an audience hears   Cues, Aural Reinforcement Support for the Overall Production  What the company hears Monitoring, Communications  Recording  Use of Sound in the Theatre What Audience Hears – Company Hears  Sound Cues - “created” sounds that advance the story Sound effects, music transitions and underscoring  Produced / reproduced through mechanical or electronic means  Mechanical – real sounds (sheet metal for thunder, crash box for breaking glass, ½ coconuts for horse galloping, actors making bird calls) Also called practical Electronic reproduction Sounds stored as signals on CDs, Minidisks, computer files Use of Sound in the Theatre What Audience Hears – Company Hears  Reinforcement of aural elements of production    Mic cues for vocal and musical performance Orchestra Mics Instrument direct feeds Use of Sound in the Theatre What Audience Hears – Company Hears  Monitoring – Providing performers and members of the company a portion of the sound from the performance to assist with their performance  Stage monitors for singers to hear the band – and themselves – Fold back  Pit monitors for band to hear vocals – and themselves  House monitoring for crew positions, back stage and dressing rooms so company can hear “what’s going on” Use of Sound in the Theatre What Audience Hears – Company Hears  Communications   Intercoms for cueing and communications among the company Recording  Live feeds of performance for film, video and audio recording Paper work, paper work, paper work… Paper work, paper work, paper work… Paper work, paper work, paper work… For Next Class  Read  The Spaghetti Factor!, Coleman  Patches and Facility Panels, Coleman Soldering and Soldering PDF   Study for Quiz [...]... the sound to drop from its sustain level to inaudibility after vibrating object stops supplying energy Sound Design  How, what and why of a show Interaction of Sound with other Show Elements  Script Identification of motivational cues - sounds listed in the script (cues that actors react to)  Identification of environmental cue opportunities – locations, time of day, season, era,  Identification of. .. reflections from walls, ceilings and other structures which do not absorb sound NOT echo  Echo consists of individual, non-blended sound images Reverb time is related to  The time it takes for a sound to reduce to an inaudible level  Loudness of sound relative to background noise  Ratio of loudness of reverberant to direct sound Short reverb time (less than 1.5 sec) is better for speech or drama... frequency sound relative to mid frequency Too much low frequency sound is said to be “Boomy” Acoustic attributes  Loudness of direct sound    Inverse square law Loudness of sound will decrease by one quarter every time the distance from the source is doubled Definition or Clarity   Good definition when sound is clear Related to intimacy, liveness, loudness of direct and reverberant sound Acoustic... Relates to the orientation of reverberant sound   Where is the reflected sound coming from It is preferable to have reverb sound coming from all directions Intensity    Like pitch, loudness is a sensation in the consciousness of a listener To produce a sound twice as loud requires 10 times the power Inverse square law  Sound level is reduced by a factor of the square of the distance away from... loud the sound is “loudness” is relative to frequency and dependant on the listener Timber and Harmonics   Harmonics – multiples of a base frequency Timber – the characteristics of a particular sound or instrument  Different harmonics combined in different levels Physics of Sound Part 2 Basic Acoustics Inverse square law Reinforcement/cancellation Interference  Phase     measurement of where... 1 Meter 120 dB Jet takeoff (20 0 ft) 110 dB Rock Concert 100 dB Train passing up close 90 dB Heavy traffic 80 dB Hair Dryer 70 dB City street 60 dB Noisy bar or restaurant 50 dB Open plan office environment 40 dB Normal conversation level 30 dB Library, Soft Whisper (5 Meter) 20 dB Quiet domestic environment 10 dB Broadcasting Studio, Rustling Leaves 0 dB Threshold of hearing in young adult Sound Envelope... Interaction of Sound with other Show Elements  Acting  Collaborate on what is “heard” on stage - Actors need to understand what sounds are part of the physical environment shared with the set and props Some sounds are there for them to react to (Motivational) Some sounds need to be originated by a performer’s action (ring a bell, turn on a radio, etc ) Monitoring of stage action to off-stage locations... individual cycles of sound waves Attack – Time it takes for sound to rise from nothing to its greatest intensity Usually short Decay – Time it takes for a sound to fall from its attack level to its sustaining level Decay time is usually short Sustain – The time during which the initial vibrating source continues to supply energy to the sound Usually perceived as the duration and intensity of the sound Release... Placement of wireless mics and stage monitoring / fold back  Interaction of Sound with other Show Elements  Costumes   Musicals – wireless mics that need to be accommodated within costumes and hair Scenic Location of on-stage devices (speakers, mics)  Collaboration on scene shifts (needs/opportunities to cover transitions using sound cues – “Functional” sound cues)  Identification of cues that... different frequencies interfere Often used in tuning Standing waves    When sound waves bounce off of obstructions, they can interfere with themselves Tends to reinforce some frequencies and attenuate others Prevented by using    Non- Parallel walls, ceilings Convex surfaces Multi-level ceiling sections Reverberance (Reverb)      Consisting of multiple, blended sound images caused by reflections
- Xem thêm -

Xem thêm: 2 physics of sound , 2 physics of sound , 2 physics of sound

Gợi ý tài liệu liên quan cho bạn

Nạp tiền Tải lên
Đăng ký
Đăng nhập