Assignment 12.1.1


a) Amplitude

Amplitude is the total height of a sound wave. A sound wave is a pressure wave. A physical characteristic of amplitude is loudness, a logarithmic measurement call a decibel unit was assigned to amplitude to measure the amount of loudness or sound pressure. The lower the units of decibels (dBs), the quieter the sound. The louder the sound the more damage is done to human hearing. Human hearing becomes damaged at 140 decibels and hearing is permanently damaged at 150 decibels.


b) Wave Length

Wave length is the distance of one sound vibration measured from crest to crest for one second.


c) Frequency

Frequency is the number of complete wave cycles that occur over a set period of time. Measured as Hertz per second, frequency has the physical characteristic as the pitch of sound which can range from low to high. To calibrate the audio in a production, the common frequency tone is 1 kHz or 1,000 Hertz. The movement of the the cycle has three phases: Compression, Rest, and Rarefaction.

Compression occurs as the wave of molecules moves upward, peaking at the crest and has the greatest amount of pressure. At the highest point, when the energy of compression can go no further, rest occurs. Rest only lasts for a micro-second because the energy of the pressure wave is beginning to shift directions due to elasticity of the pressure’s molecules. The molecules then begin to lose their energy and start pulling apart. This loss of energy and separation is the rarefaction phase and the soundwave descends to the lowest point, the trough.

Frequency plays an important part in audio production as this creates the aural impression. The perception of sound by humans is the human frequency spectrum. The normal range for hearing in this spectrum is between 20 Hz to 20,000 Hz. This spectrum’s range is broken into three bands, bass, midrange, and treble. These bands are used determine the audio output in sound systems using a 3-band equalizer.


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