Audio Flashcards
Which aspect of sound is measured in decibels?
Volume
Why are music tracks produced in a MIDI format?
A MIDI file format only records the digital notation of a music track and can be transferred across multiple computer platforms. The sounds and instruments used to play the music can be changed without any loss of quality. Specialised MIDI instruments can be used to produce the music.
What is the formula to determine file size of an audio file in bytes
File Size = Sample Rate (in MHz) x Sample Size / 8 x number of channels x duration (seconds)
The formula used to determine the bit rate of a digital sound file in kbits/s is as follows:
Bit rate = sampling rate x bit depth x number of channels
What would be the file size of a sound file that is recorded at 100kHz at a 16-bit depth in stereo and is 15 seconds in duration?
file size = 100 x 16 / 8 x 2 x 15 = 6000 kb = 6 Mb
How could a .wav file be optimised for use on the web?
To optimise a .wav file for use on the web, it can be compressed to make it smaller. Typically, this may be done by converting the WAV file to an MP3 file format.
What is the unit of measure in which the sampling rates for audio files are measured?
Hertz or Kilohertz
A multimedia company has been commissioned to develop a promotional video for a famous tourist attraction.
(A) Outline factors that can affect sound quality when creating the video.
Sample Answer
Large sampling rates per second of captured sound will result in higher quality sound captured for the video. Also, the bit depth of 8 bit sound will not produce the quality of 16 bit sound as the number of bits of information recorded in each audio sample is greater in 16 bit sound.
Other Answers could include:
- Sampling rate for audio capture
- Quality of microphone use for capturing sound
- Sample depth (bit depth) 8 bit sound to 16 bit sound
- The file type used to store captured sounds may affect the quality as some files, such as MP3 files, are compressed resulting in some sound frequencies being removed.
Explain the importance of sound synchronisation.
Answers may include explanations about:
- Sound synchronisation is the matching up of video and audio
- Playback of video without any audio delay
- Creates a sense of harmony and engagement when audio and video is in sync; for example a countdown timer being displayed as music beat is increasing.
- Without sound synchronisation the audience is not engaged and loses focus on the aim of particular scenes.
A producer chooses to use the WAV file format over MP3.
Explain the benefits of this decision .
WAV is an uncompressed file format, which means the recording is reproduced without any loss in audio quality. They are large in file size, which means they can hold more data over the MP3 format. Compressing a file causes quality loss which can be picked up by listeners. The WAV file is a simple format and are fairly easy to process and edit.
What is the main advantage of using an MP3 file format?
(A) - Higher volume
(B) - High quality
(C) - Prevents piracy
(D) - High compression rate
(D) - High compression rate
An audio file is saved with 2.1 channel sound.
How many speakers are designed to be used in this configuration?
(A) - 1
(B) - 2
(C) - 3
(D) - 4
(C) - 3
What is the difference between analogue and digital audio?
Analogue sound is vibrations of air particles that travels through a medium and can be heard when they reach an animal or human ear. Analogue sound can be represented with a sine wave.
Digital audio is sound that is in digital form. It can be recorded, transmitted or reproduced. Digital audio can be understood by a computer with a series of O’s and l’s.
Which of the following is defined as the number of times an analogue audio signal is measured per second?
(A) - Volume
(B) - Sample rate
(C) - Sample size
(D) - Frequency
(B) - Sample rate
A midi file format would be more beneficial to use over a WA V or MP3 in which of the following scenarios:
(A) - A singer wishes to record their voice for high quality reproduction.
(B) - A pianist wishes to collaborate on the creation of a musical score.
(C) - A rock band wishes to share their music over the internet.
(D) - A tutor needs to upload voice recordings for tutorials online.
(B) - A pianist wishes to collaborate on the creation of a musical score.
Explain how the way MIDI files are stored makes them beneficial to use.
MIDI files are easily editable
It is the standard control/protocol for the interchange of musical information between a variety of different devices. These include musical instruments, synthesizers, keyboard controllers, sound cards and computers.
It is used to create, store and reproduce a musical sequence by using a set of instructions such as Note On/Off, Pitch, Velocity, etc.
These instructions describe what notes are to be played, when they are to be played, how long each note is to be held, with what loudness, at what pitch.
It is a very small file type as it does not contain audio waves but rather instructions on how to create the music.
It is also very easy to change the file by simply altering, adding or removing some of these instructions.
You can adjust the note, pitch, tempo, etc …
The interface connects with a soundbank which can increase its capabilities.
Can carry up to 16 channels of audio
Allows for consistent quality sound
