Audio and equipment (foun.dig.med) Flashcards
What is digital audio sampling?
The process of transforming a musical source into a digital file. Digital audio recording does this by taking samples of the audio source along the soundwaves at regular intervals.
What is an analogue sound wave?
Moves smoothly. An audio wave recorded/used in its original form with the signals stored as a continuous signal.
What is a transducer?
A transducer is a device which converts energy of some form into energy of another form. Something that coverts one form to another. eg. headphones are made for sound coming out, microphones are made for sound coming in.
eg. Sound waves- microphone transducer – microphone output signal,
What is an analog recording?
Analog recording captures the continuous change in the sound wave from your instrument or voice. It’s like drawing a picture of the sound. This is done with a microphone that changes the sound into an electrical signal. The electrical signal then gets recorded onto a physical medium like a vinyl record or a magnetic tape.
An analog tape draws a waveform and so can record big sounds.
What is a digital recording?
Digital recording stores audio as binary data—just a bunch of 1s and 0s. This data can be stored on a variety of media such as CDs, hard drives, or even in the cloud. Digital recording software allows you to edit and manipulate sounds in ways that were impossible in the analog era.
Can only record up to half the sample rate. Most audio interfaces cut off sounds out of hearing range.
Digital audio interface contains: mic reamplified and analog to digital converter.
What are waveforms?
Captures everything we hear on a single line. If you record multiple instruments, the line will be more jagged. A graph that displays amplitude or level changes over time.
A WAVEFORM ALWAYS MOVES UP AND DOWN.
AC = Alternating current (a digital signal is an AC).
DC= Direct current (eg. Batteries).
What is the nature of a mic pre-amp?
A mic pre-amp doesn’t change the sound, just makes it bigger. This is the first stage of an audio interface.
STAGE 2 OF AUDIO INTERFACE = ANALOG TO DIGITAL SIGNAL.
Snaps to a grid, as close as possible to the line.
The higher the sample rate, the more accurate the sound.
With a lower sample rate, the accuracy of the tone of a sound would suffer.
An accurate waveform is always important when recording.
What are the 4 characteristics of a waveform?
Wavelength
Amplitude
Frequency
Velocity
The meaning of wavelength on a waveform?
The wavelength of a wave is the length in meters from the start to the end of one full cycle of the waveform. Eg. Crest to crest.
The meaning of amplitude on a waveform?
The amplitude is the maximum displacement of a wave from the centerline to the peak, not from peak to peak. The greater the distance from the centerline of a waveform, the more intense the pressure variation will be within a medium, hence the louder it is perceived.
Amplitude is measured in two ways:
1. Zero to peak value which measures the maximum positive or negative signal level.
2. Root-mean-square (RMS) value measures a more meaningful average level, like that at which humans hear.
Meaning of frequency on a waveform?
Frequency is how many complete waves there are per second passing a certain point. The frequency indicates the rate of pressure variations of cycles per second of a wave.
Frequency is measured in hertz. Hertz is a unit of frequency and equals the number of cycles per second.
The frequency of a sound determines the pitch, the sensation of how low or how high a sound is.
Lower frequency sound waves have longer wave lengths and lower pitch.
Higher frequency sound waves have shorter wavelengths and a higher pitch.
The frequency range in which humans can hear is 20Hz to 20,000Hz and is called the audible range, or the audio spectrum.
Meaning of velocity on a waveform?
The velocity is the speed and direction of a soundwave.
Soundwaves travel at different speeds through different speeds through different mediums. Through the air, sound travels at 344 meters per second.
Generally speaking, the denser the medium, the faster sound travels through it.
To find the velocity of a wave, the following equation is used:
Velocity (V) = Frequency (f) x Wavelength (λ)
Analog vs digtial?
ANALOG:
Refers to an audio recording using a “replication method” capturing the original sound waves. (eg. Vinyl records, cassette tapes, and reel-to-reel).
DIGITAL:
Refers to an audio recording using a “sample “ method. The original sound is captured at a specified rate. (eg. CDs, mp3s, and DAT).
