Mono & Stereo Recording

Mono Recording • Mono simply indicates the use of a single channel. Mono includes

the use of a single microphone used to record a sound, which is then played through a single channel through a speaker.

• The easiest way to check if a sound is a mono recording is through a set of headphones, incidentally, you can easily distinguish whether or not the sound plays through one headphone and not the other.

• Mono recording was typically used before the development of stereo recording.

• All the sound signals recorded are channel through a singular audio channel, therefore mono sound delivers no implication of sound perspective, for instance there is no hint of the direction in which the sound is being recorded from.

Mono Recording

Advantages • Mono file sizes are around half the size of their

stereo counterparts

• High resolution files can be recorded with relatively low file sizes

• High resolution files can be recorded around the same size file as a low resolution stereo file

• It is much easier to mix mono sounds than it is with stereo

• Mono sounds are much easier to manipulate in editing programmes

• Everyone hears the exact same signal

• Mono systems are suitable for reinforcing a sound

Disadvantages • There is no sound perspective

• It is impossible to tell whether or not a sound has been recorded from a distance

• Films that use mono sounds do not provide as much as an impact than if the film was recorded using stereo sounds

Uses of Mono Recording • The main advantage of mono recording is that it is

excellent for reinforcing a sound. This is particularly useful for audio that is heavily based on speech, such as a tutorial.

• Mono sound can reinforce the speaker’s speech, delivering a clear and understandable sound, making it easier for people to recognise and understanding the audio that is being conveyed.

• Mono provides a better quality of sound for a small size than a stereo recording, mainly since stereo uses two types of channels therefore the recording will be two times the size.

Stereo Recording • Whereas mono recording has one independent audio channel, stereo has two channels.

• Signals that are reproduced through stereo recording have an exact correlation with each other, so when the sound is played back through either speakers or headphones, the sound is a mirrored representation of the original recording.

• Stereo recording would be useful in situations that require the use of sound perspective, for instance the clear location of instruments on a stage.

• The stereo systems must have an equal cover over the two audio channels.

Stereo Recording

Advantages• Provides sound perspective

• Gives an idea of the direction the sound is coming from, or how it has been recorded

• Provides better experience when listening to songs or films

• It is possible to tell whether or not the sound has been recorded from a distance

• Offers the possibility of multi-track recordings

Disadvantages • Since stereo files use two audio channels instead of

one, the files sizes are going to be a lot bigger

• High resolution stereo files are relatively big files

• Mono sound files can be recorded at high resolutions for half the file sizes of stereo files

• Stereo files are harder to edit than mono files as there are two channels to work with

• The sound is played equally over two channels, therefore if one channel is broken, the sound quality is not only played through one speaker, it is also halved or some of the audio is missed out altogether

• Stereo is a lot more expensive to set up

Uses of Stereo Recording • Stereo recordings provide sound perception, which indicates that

someone can tell the direction a sound has been recorded, for instance they can tell how far away or how close a sound has been recorded.

• This is particularly useful when trying to develop the experience when listening to a sound. For instance, this may be used when listening to a film’s soundtrack or when playing a game.

• Stereo sounds adds to the experience, although it may not give as good a quality of sound as mono recording would provide, it is still has more popularity than its counterpart.

• Stereo sounds provides the listeners with more audible cues, as it is not just recording the sound of a musical instrument, but it is also recording the area around that instruments, so the listeners can tell how far away or how close it is to the microphones.

Sound Quality • Sound quality measures the worth of an audio recording. Sound quality can also

be a measurement of sound accuracy, especially when considering the value of a digital sound. Sound quality can be a measurement of how accurate a digital system reproduces an original sound wave.

• Whereas these are a measurement of the value of sound, when it comes down to it, it is really up to the listener’s opinion whether a sound has good quality or not.

• Sound quality can be affected by a number of elements, and these can be applied during anytime of producing the sound, for instance faults in equipment could occur during the recording stages, or quality can be reduced by which file formats are used when storing digital sounds.

• Also sound quality is determined by the compression method used to store the files, for instance it depends on the number of audio channels open, i.e. mono, stereo, multi-channel, etc…

Bit Rate • Sounds can be recorded in a variety of formats. However, when choosing

the right formats in which to store the sound, quality and size need to be considered. For instance the smaller the sound file the poor the quality, however this cannot be said for lossless compression, which preserves the quality of sound whilst making the file size small.

• Therefore compression methods need also to be considered.

• Also sound quality is determined by the bit rate. Bit rate is classified by the number of samples a digital recording takes per second. For instance, the less the sample rate the poorer the sound will be represented. Bit rates take samples of the original sound wave, meaning that any sound recorded between these samples is ultimately lost. This is a major disadvantage for digital recordings. However, bit rates can be increased to high resolutions so that they record more samples per second. Incidentally, the greater the sound rate the more accurate reproduction of the original sound wave is being created.

Bit Rate Image Example

Sample Rate• The sample rate defines the number of sample, of a audio frequency, taken per

second. Sample rates are taken from a continuous signal, like an analogue signal. Sample rates are measured in hertz. As well as sampling frequency, there is also a sampling period in which the time between samples are measured.

• In some cases, oversampling and undersampling can be evident. Oversampling is when the sampling rate is twice that of the original signals bandwidth. Whereas undersampling is the reverse.

• Sample rates take pieces of an original analogue recording, in other words the end results in a choppy representation of the original sound. The more frequent the sound rate is, the better the approximation to the original sound is. Unfortunately, the higher the sample rate, the more space the file is going take up on the computer’s hard drive. Incidentally, it is a debate whether to have a better quality sound with a higher sample rate, but large file size, or have a poor quality sound with a low sample rate but a small file size.

Sample Rate Example

Uncompressed File Formats • Uncompressed formats are files that have not been altered to make

smaller, meaning they have no compression. Audio date stored as these types of files are relatively large file sizes. .WAV files are an example of an uncompressed file.

• Popular uncompressed file formats include:– .WAV – PCM– .AIFF– BWF

• .WAV and AIFF file formats are flexible formats designed for storing any audio files of any combination of bit rates and sample rates. Consequently, this flexibility makes these types of files storing original sound recordings.

• BWF files were created to be the successor to uncompressed .WAV files.

Uncompressed Formats Comparison.WAV Files• The most popular uncompressed file format is the Microsoft Wave Format (.WAV). The .WAV format was

specifically designed for the Windows operating system, however it has no integrated onto other systems, meaning it has a wide familiarity with audiences.

• .WAV files can store a high-quality audio recordings, and has few limitations. One of these few limitations include the inability to store metadata used to describe its audio content.

• .WAV file sizes are limited to 4GB. This limit is caused by a 32-bit address header, which imposes a limit of 4GB.

BWF Files • BWF files were designed as a successor to the old .WAV files. In terms of functionality, it is practically

identical to it .WAV counterpart. Perhaps the only difference that it includes is an extra header file, containing metadata.

• BEXT is a format used to add metadata to a .WAV file format. • Unfortunately .BWF files are limited to 4GB for the same reasons as .WAV files.

AIFF• AIFF files were created by Apple, and it stands for Audio Interchange File Format. It works similarly

to .WAV, however it uses different methods of dividing data into manageable chunks. • It is available for a wide range of platforms. • AIFF files can store loop points, meaning that they are capable of playing back musical samples.

Best Uncompressed File Format.WAV• Even though .WAV files have a limitation of 4GB, it is still a relatively large file size.

4GB will allow up to 6 hours of audio recording, which, in some case, would be quite difficult to exceed. Even though they have a limitation, the maximum size is still a large file size that most users won’t even come close to reaching.

• .WAV files can be converted into a format of “lossless” compression, which means that the file won’t lose any of its quality when it is stored. Incidentally, this has an advantage over MP3 files, which are a form of “lossy” compression.

• Since .WAV files are generally such big files, this means that they can have high bit and sample rates. Originally, .WAV files were designed to store a variety of audio formats, which used a combination of different bit and sample rates.

• Also .WAV files can be edited easily, so they can be easily used in audio editing software. In comparison to other files, such as MP3, .WAV are a lot more diverse.

• .WAV files are perhaps the most popular audio file formats used today, even in comparison to compressed file types and other uncompressed formats.

Compressed File Formats Lossless Compression • Lossless compression formats indicate that no quality of the original recording is lost when it is stored.

However, lossless compression requires a lot more processing power for the files to be compressed when stored, and uncompressed when played back, than other compression techniques.

• Lossless compressions allow the original audio recording to be reproduced as accurately as possible. Common formats include:

– Apple Lossless – WavPack– FLAC

• Lossless file compression have a compression rate of around 2:1, meaning that they take up half as much room on the hard drive than the original uncompressed files.

Lossy Compression • Lossy compression is the alternative compression technique when compared to lossless. Lossy

compression enable a greater compression rate than its lossless counterpart. However, lossy compression cannot be accomplished with reducing audio quality. File size reduction is accomplished by subtracting some of the original data, meaning that when the file is compressed some of the data is lost.

• Popular lossy compression files include:– MP3– AAC

• Lossy compression files are generally measured by the size of their bit rates. The lower the bit rate, the smaller the file, meaning the less quality is lost through compression.

Compressed Formats ComparisonThe best compressed audio format is decided based on the needs for the file.

For instance, with users demanding high quality sounding audio, then a file with a lossless compression method, such as FLAC is probably the best option.

Yet for some looking for cheap sound effects, then they are possibly looking for a small file size rather than a good quality one.

Purpose Suggested Format

Turning that once-in-a-while CD you listen to into MP3 format

You won't need top-quality sound; you can record it in MP3 128 bit, WMA 96, or Ogg Vorbis 96 with a clean conscience.

A CD you listen to once or twice a month

Variable bitrate compression using Ogg Vorbis is ideal, usually around a 96-bit median. This is still excellent quality at the right size.

A CD you listen to weeklyVariable bitrate compression using Ogg Vorbis is ideal, usually around 128-192 bit median. For most listeners, this will be indistiguishable from CD-qualtiy.

Your favorite album FLAC is advised for top quality.Table from: http://infoanarchy.org/en/Best_Compressed_Audio_Format

Best Compressed File Format MP3• Music can become portable as MP3 can compress files into manageable

sizes. Can be transferred to portable music players.• MP3 files can be easily shared and streamed across the internet, since

they are so easy to store and manage. • CDs can be made from collections of MP3 files. • Easy to transfer over the internet since MP3 files can be compressed to

relatively small sizes, so they won’t reduce bandwidth. • MP3 files can reproduce an original sound recording up to twelve times

small than the original file size. For instance a CD worth up to 5 minutes of music can take up to 40MB of hard drive space, whereas MP3 files of the same CD could only take up 3-5MB.

• MP3 have a worldwide distribution. Most websites provide MP3 files to be downloaded instantly off their servers without having to compression or make sure that the file is compatible with the operating system.

• MP3 offers a wide range of versatility.