Test your basic knowledge |

Digital Audio

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
  • If you are not ready to take this test, you can study here.
  • Match each statement with the correct term.
  • Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. 1.) Bit Rate x Sample Rate (you'll get b/sec) 2.) Multiply by 60 if converting seconds to minutes 3.) Divide by 8 to convert bits to Bytes and get B/min 4.) Divide by 1 -024 to get KB/min and keep doing it until you get desired bit rate specification






2. Single- pin RCA cable or fiber- optic TOSLINK connector used for digital transfer; 75O coaxial - 2- channel unbalanced; 'Consumer' format of AES3






3. AES






4. As sample rate is increased more room is created for a smoother slope of the attenuation band because Nyquist limit extends well beyond range of hearing with each increase






5. Twice as many samples as the highest frequency at minimum; Sampling rate totally controls frequency response






6. Voltage -> Dither -> Anti-Aliasing (Low Pass Filter) -> Sample & Hold Circuit -> Successive Approximation/Quantizer --) 100111010 (PCM Audio File)






7. Data is transmitted over fiber optic lines; Uses a TOSLINK connecter instead of an RCA type; Can transmit multi- channel audio; Not susceptible to ground hum and loops; Able to support far higher rates of data transfer over greater distances than coa






8. Contains all even and odd harmonics associated with a fundamental tone - making it a rich source for modeling other sounds; Amplitude of each overtone decreases exponentially as a ratio of the harmonic's frequency to that of the fundamental






9. Measurement at regular intervals of the amplitude of a varying waveform (in order to convert it to digital form); There must be a minimum of 2 samples for each cycle in a waveform






10. Series of dots and dashes representing the letters of the alphabet; Most common letters are represented by the shortest dots and dashes; Example of entropy coding






11. Overtones that contribute to the timbre of a sound and make up a complex waveform's physical characteristics






12. Signal voltage is relayed to a register from sample- and - hold circuit; Holds reference frequencies in binary form that decrease in value; Finds approximated value & assigns binary number accordingly






13. Computer program or device capable of encoding and/or decoding a digital data stream with the end result being a reduced file size






14. Fractional part of a floating- point number; Also called the mantissa; Defines precision






15. Serial Copy Management System; main difference between AES3 & S/PIDF






16. VBR; Most common & best data reduction technique; Codecs that encode data by determining how dense or sparse areas of the audio are; Can result in buffering issues






17. Father of modern information theory; Solidified the Nyquist Theory by adding the concept that bits per second (binary representation of audio signals) must be at equal intervals to accurately represent data






18. Electromagnetic receptor that detects the radiation known as visible light






19. Reduces A/D sample rate from the oversampled rate to nominal rate by turning series of one- bit samples into a series of multi- bit PCM samples; (ex. => 2.8MHz sample rate converted to 44.1kHz and simultaneously converts 1-Bit samples to multi- bit);






20. A time regulator that makes all samples and bits to align when working with interconnected digital devices; Basically a signal that all of the digital devices refer to when operating.






21. Digital and analog processing capability is combined on a single microchip allowing for 1- bit resolution at high sample rates






22. AAC (Advanced Audio Coding); MP3; RA; WMA; OGG Vorbis; Dolby Digital/AC-3; DTS; ADPCM






23. Measure of sound pressure over the frequency spectrum - for which a listener perceives a constant loudness when presented with pure steady tones






24. Number or variable that represents the number of times the base of a power is used as a factor; Defines magnitude






25. Branch of psychology concerned with the subjective perception of sound






26. The mathematics - algorithms - and the techniques used to manipulate signals after they have been converted to digital form






27. Same as 'aliasing'






28. A situation where a calculated value cannot fit into the number of digits reserved for it






29. Eliminates frequencies above the Nyquist limit from becoming samples; Occurs prior to quantization






30. 7.95 GB; SS/DL






31. Pertaining to hearing or sound; Combination of the intensity of air pressure molecules with amplitude






32. Improper (false) sampling of high frequencies that cause much lower frequencies to be produced when the audio is reconstructed; Foldover happens at higher frequencies as harmonics reach levels that exceed the Nyquist limit.






33. Describes various optical disc characteristics including the size and shape of the disc - the size of pits - the speed at which the disc spins - and a multitude of aspects regarding the specifications of the player itself






34. Reduces the percieved distortion due to quantization error; Low level white noise source is introduced to make the profile of the quantization 'noise' more irregular; Useful when reducing the number of bits per word in a signal (i.e. when converting






35. Snippets of time in which frequency analysis takes place in a perceptual codec






36. 16-Bit; 44.1 kHz; PCM; Stereo






37. Subtract place values from the decimal number and place ones or zeros in the correct places






38. Visual graph that shows how loud a sound is at different frequencies






39. Sample Rate x Bit Depth x # of Channels






40. The set of rules that computers use to move files from one computer to another on an internet






41. Amplitude meter that takes the square root of all instantaneous amplitudes and averages them to find a mean and squares that value; Useful with particularly complex waveforms






42. CobraNet; EtherSound; Dante; AVB (currently under development)






43. A sample- by- sample operation on two signals






44. Allowance of noise floor below that which is required for the final product






45. Smallest interval measurable by a scientific instrument; Defined by bit rate (sample rate x bit depth)






46. Represents the amplitude component of the digital sampling process; Technique of incrementing a continuous analog event into a discrete set of binary digits (bits)






47. The frequency range that is allowed through a filter






48. Waveform of a pure tone showing simple harmonic motion






49. Signal that uses variable voltage to create continuous waves resulting in an inexact transmission






50. Also known as equal loudness curves; Graph that indicates the average ear sensitivity to different frequencies at different SPL levels (as volume increases - these curves flatten out)