Sound - sound effects - sound events

 List of sounds in categories for radio drama (below)
 LEARN ABOUT THE PHYSICS (or science) OF SOUND (below)
 Fictionalisation of sound - see Darren Copeland's Ten Questions for a Listener - comments - learning about sound and listening (to another page on this site)
 Listening - how people listen (to another page on this site)
  Film Sound Terminology at
 Randy Thom articles about film sound at
 Acoustics FAQ at


For sound effects in film and theatre, and a general introduction, see (Wikipedia):

Meat safe microphone 1924 - from the side - heavy mic is suspended

List of sounds in categories for radio drama

 vocal sounds - human speech - dialogue - the voice stream
 vocalising from animals and insects, sound-making from insects (barking, mooing, insect shrieking, scratching).
 non-vocalised sounds of human origin (scratching, clothes rustling, footsteps) - these indicate the 'more than words' (or embodying the dialogue) - representing living in the vocal stream (Beck, Radio Acting, 61).
 Non-vocalised sound events of sentient beings which are non-human (animals moving, insects clicking)
 Sound events not originating from living beings, that is originating from nonsentient objects (stones falling, machines, thunder).
 Atmos, background, soundscape, ambient sound, including 'room tone' and the 'aural fingerprint' of locations
 Silence(s). Stearns, 1995 describes silence as: 'A dramatic element. It can be very loud.' (See Shingler and Wieringa, 1998, 54 for a revealing discussion.) See silences - different sorts and Silences and the overall design



Sound requires a medium to exist. There is no sound when a space ship explodes in deep space.

Air molecules provide the necessary element for sound transmission to occur.

BELOW FROM -  Acoustics FAQ at

*** 2.1 What is sound ?

Sound is the quickly varying pressure wave within a medium. We usually mean audible sound, which is the sensation (as detected by
the ear) of very small rapid changes in the air pressure above and below a static value. This "static" value is atmospheric pressure
(about 100,000 Pascals) which does nevertheless vary slowly, as shown on a barometer. Associated with the sound pressure wave is a flow of
energy. Sound is often represented diagrammatically as a sine wave, but physically sound (in air) is a longitudinal wave where the wave motion
is in the direction of the movement of energy. The wave crests can be considered as the pressure maxima whilst the troughs represent the
pressure minima. ....

What makes sound?
Sound is produced when the air is disturbed in some way, for example by a vibrating object. A speaker cone from a hi-fi system serves as a
good illustration. It may be possible to see the movement of a bass speaker cone, providing it is producing very low frequency sound. As
the cone moves forward the air immediately in front is compressed causing a slight increase in air pressure, it then moves back past its
rest position and causes a reduction in the air pressure (rarefaction). The process continues so that a wave of alternating high and low
pressure is radiated away from the speaker cone at the speed of sound.

*** 2.6 How does the ear work ?

The eardrum is connected by three small jointed bones in the air-filled middle ear to the oval window of the inner ear or cochlea, a fluid-
filled spiral coil about one and a half inches in length. Over 10,000 hair cells on the basilar membrane along the cochlea convert minuscule
movements to nerve impulses, which are transmitted by the auditory nerve to the hearing center of the brain.

The basilar membrane is wider at its apex than at its base, near the oval window, whereas the cochlea tapers towards its apex. Different
groups of the delicate hair sensors on the membrane, which varies in stiffness along its length, respond to different frequencies
transmitted down the coil. The hair sensors are one of the few cell types in the body which do not regenerate. They may therefore become
irreparably damaged by large noise doses.

*** 2.9 How does sound decay with distance ?

The way sound changes with distance from the source is dependent on the size and shape of the source and also the surrounding environment and
prevailing air currents. It is relatively simple to calculate provided the source is small and outdoors, but indoor calculations (in a reverberant field) are rather more complex.

If the noise source is outdoors and its dimensions are small compared with the distance to the monitoring position (ideally a point source), then as the sound energy is radiated it will spread over an area which is proportional to the square of the distance. This is an 'inverse square law' where the sound level will decline by 6dB for each doubling
of distance.

Line noise sources such as a long line of moving traffic will radiate noise in cylindrical pattern, so that the area covered by the sound energy spread is directly proportional to the distance and the sound will decline by 3dB per doubling of distance.

Close to a source (the near field) the change in SPL will not follow the above laws because the spread of energy is less, and smaller changes of sound level with distance should be expected.

In addition it is always necessary to take into account attenuation due to the absorption of sound by the air, which may be substantial at higher frequencies. For ultrasound, air absorption may well be the dominant factor in the reduction.

 Human hearing at

 Decibels at






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