Theory of sound

What is sound?

Sound works by saving a sequence of persistent waves of pressure that penetrates through compressible media such a solid, liquid or gas. Waves can be refracted, attenuated, or reflected. Things that can affect the sound waves is the density and pressure of the object, the motion of the medium if it is moving the sound will be further transported. Lastly the viscosity of the medium it can alter the rate at which the sound is then attenuated. However, at a standard temperature and pressure in air, wavelengths of sound waves had ranged from 17m to 17mm.

When talking about sound waves there are other generic properties within it, such as frequency which is measured in cps (cycles per second) which measures the duration of one cycle in a repeating event, for example if bang a drum at 120 times a minute, its period is half a second. Another property is Amplitude which measures the degree of change whether that’s positive or negative in atmospheric pressure caused by sound waves. The main effect of amplitude that we hear is the loudness.

Measure of sound

Measure sound intensity also referred to as sound power or sound pressure in units called decibels. Decibels (dB) are named in honor of Alexander Graham Bell, the inventor of both the telephone and the audiometer. An audiometer is a device that measures how well a person can hear certain sounds.

Frequency, sometimes referred to as pitch, is the number of times per second that a sound pressure wave repeats itself. A drumbeat has a much lower frequency than a whistle, and a bullfrog call has a lower frequency than a cricket. The lower the frequency, the fewer the oscillation humans can detect sounds in a frequency range from about 20 Hz to 20 kHz. (Human infants can hear frequencies slightly higher than 20 kHz but lose some high-frequency sensitivity as they mature; the upper limit in average adults is often closer to 15–17 kHz.)

What is Diegetic?

Diegetic sound usually refers to a game's sound effects, background ambience and the dialogue which takes place between characters. Any sound that originates from a source within the video game’s world is referred to as diegetic. It is a sound which you would be able to hear if you were inside the game’s world.

Examples of Diegetic Sound

·      In Super Mario, Mario jumps and an iconic sound effect accompanies the jump.

·    Pressing the acceleration button in a racing game leads to the sound effect of a car revving up.

·    A non-player character (NPC) says something to the player and the player hears the recording of a voice actor.

Non diegetic

Non-diegetic sound is a sound whose source is neither visible on-screen nor has been implied to be present within the game’s world. It is external to the in-game world and is only heard by the player. Non-diegetic sounds include the commentary of a narrator, an original soundtrack (OST) or SFX added for dramatic effect.

Examples of Non-Diegetic Sound

•          In Grand Theft Auto, the player is thrown from a car and dies, initiating the ‘wasted’ sound effect
•        In Space Invaders, the background music increases in tempo as enemies approach the player.