Fundamentals of Sound

what are the three components of sound

source, path, reciever

what is vibration

pressure waves in a medium creating sound

what is amplitude

the maximum amount of displacement of a vibrating particle from its rest position

what is wavelength

the distance a sound wave travels during one cycle of vibration, distance between adjacent regions where identical conditions of particle displacement occur

what is frequency

the number of occurrences of a repeating event, number of completing vibrations in one second

what effects pitch

wavelengths and frequency

what effects volume

sound pressure level

what changes the speed of sound

material of medium it is passing through

what is sound intensity

sound pressure in decibels

what are three properties of an acoustic surface

reflection, absorption, diffusion

what is the purpose of reflectors

capture and redirect sound energy to increase sound level and clarity

what is absorption coefficent

fraction of the incident sound energy that a material absorbs

what is a porous absorber

sound energy is reduced as air moving through the small pores loses energy through friction

what is a membrane absorber

thin flexible panel or sheet place over an air cavity, panel vibrates when sound hits and converts part of the sound energy into heat

what is a resonanting absorber

perforated panels or slotted openings installed over air cavity, vibrates strongly at a particular frequency

what is scattering coeffiecent

ratio of the non specular reflected sound energy to the total reflected energy

what is sound transmission

passage of sound from one space to another either through air or through building elements

what impacts sound transmission

mass and isolation

what is free field

sound waves spread freely from the influence of reflective surfaces

how many decibels does sound drop when distance doubles in free field

six decibels

what is a reverberant field

an enclosed space where sound reflects

what impacts reverberation time

room volume and shape, amount of absorption, surface materials, frequency of sound, furniture and occupancy

what is reverberation time

length of time required for sound to decay 60 decibels from initial level

what is the calculation of reverberation time

0.161 x V/A

what is noise reduction coefficient

average of the absorption coefficients at octave band frequencies

what causes a flutter echo/acoustic defect

repetitive reflection of sound between parallel or concave surfaces

what are design tools for designing for sound

reverberation time, ray diagrams, acoustic simulation, sound design concept