Atmospheric Pressure
 The force exerted against an object by the weight of the air above it to the top of the Earth’s atmosphere.
 Hertz
 Cycles per second
 Frequency
 The number of occurrences of a repeating event per unit of time (measured in hertz)
 Wavelength
 The distance travelled to complete one cycle of a wavelength
 Amplitude
 The magnitude of change in the oscillation of a sound wave (how high and low the wave goes.) This translated to how loud we hear the sound.
 Phase
 The comparison of where in a wave cycle two sine waves of the same frequence are at the same point in time. It is measured in 360 degrees.
 Specular Reflection
 Mirror like reflection. The angle that the sound wave first strikes the surface is the same angle with which it reflects back.
 Diffusion
 The breaking up of sound by reflection back in many directions
 Diffraction
 The ability of sound to move around physical barriers and through small opening in barriers with little to no effect on the wave energy
 Fundamental
 The lowest frequency in a complex tone
 Partial
 Any sine waves that make up a complex tone
 Harmonic
 Partials that are whole integer multiples of the fundamental
 Acoustic Envelope
 The amplitude change over time of a complex sound. Broken down into 3 parts– attack, internal dynamics, decay
 Transducer
 Any device that converts one form of energy to another
 Decibel
 A ratio measured against a constant reference point– in sound, the reference could be voltage, SPL, of full-scale digital clipping for example.
 SPL
 Sound Pressure Level. The pressure of sound vibration measured at a specific distance.
 Threshold of Hearing
 The quietest sound a human could hear
 Threshold of Pain
 The point at which sound pressure causes pain in the human hearing mechanism
 Reverberation TIme (RT)
 The time it takes for the reverberation to decrease by 60 dB from its original level
 Transmission Loss (TL)
 THe reduction of SPL of a sound source as it passes through a physical barrier.
 Electrical Insulators
 Materials that can’t conduct electricity very well
 Electrical Conductors
 Materials that conduct electricity very well
 Voltage
 The difference in charge (electrons) between two points. The greater the difference, the more the charge wants to move (more potential energy).
 Conduction
 How well charged particles (electrons) can move through a given material.
 Impedance
 A measurement of total opposition to the flow of current in a circuit
 Electromagnetic Induction
 A changing magnetic field will induce a current in a circuit.
 Electromagnetic Interference
 EMI- electromagnetic induction that occurs accidentally or creates a current that we don’t want (or corrupts the signal that we do want)
 Dynamic Range
 The difference between the noise floor and the maximum volume before the distortion of the signal is considered too much. The total potential useable range.
 Signal-to-Noise (SNR)-
 This is an active measurement of how much difference there is between a signal as it is moving through an amp and the noise floor. The actual range as it is happening.
 Amplifiers
 Any device that changes (usually increases) the amplitude of a signal. An amplifier circuit is usually created using one of the 3 following components: tubes, transistors, op-amps
 Binary
 Composed of two piece and is the language used to represent digital data of any kind.
 Fourier Transform
 Every complex sound is made up of a bunch of sine waves (single frequencies). ANY complex sound can be broken down into these individual frequencies and then reconstructed.
 Nyquist-Shannon Sampling Theorem
 If you know the highest frequency present in a complex sound, as long as you have any two evenly spaced samples charted along that wave, you can reconstruct the complex wave perfectly.
 Quantization
 The process of mapping a large set of input values to a smaller set. In digital audio, this is the technique used to represent dynamic range.
 Sampling rate
 How many ‘snapshots’ are taken of an analog signal over time. Ex: (44.1khz (CD), 48.kHz (DVD and vid)…)
 Bit Depth
 a Measurement of dynamic range in digital audio where one bit equals roughly 6db increments. Ex: 16bit (CD), 24bit (DVD Blu Ray), 32bit (used for extra headroom when changing volume digitally)