UNIT 25

Digital Audio

Digital audio is

technology that can be used in sound recording and reproduction systems. 

It will record,store,generate,manipulate and reproduce sound using audio signals encoded in digital form

Analogue

wave is recorded or used in it's original form

an analogue recording is one where a property or characteristic of a physical recording medium is made to a vary in a manner analogous to the variations in air pressure of the original sound

What is an audio signal path/flow

signla flow is the order of operations a sound goes through

when you record an instrument, the sound goes through different stages before you hear it through speakers/headphones

process of recording

sound goes through the microphone

audio lead goes through the recorder input

recorder input goes through the record pre ampilfer

adc to the recording medium

Process or replaying

Recroding medium (Disk,hard drive, SD) goes through the digital to analogue converter(DAC) and then through the replay pre-amplifer) to the power/headphone amplifer and then to the loudspeaker/headphones and to the sound

recording levels 

When you are recording, audio level should stay on the negative side of the number scale and never go above 0 (db). Anything above this results in disortion,which wil make your audio torture to listen to, it suggested to keep your level at around -10 to -12, but this can vary depending on your project and yuor subject.

Odb doesn't mean "no sound". Instead, it refers to the highest level that a digital system can handle without clipping the signal 

Sound file formats

audio coding formats or audio codecs are those strange files names you next to your favoutire songs.

Metadata

is what makes it easy for us to browse our music without investing hours of time alphabetizing and folder creating. It involves information such as...

Artist

Album 

track

Genre

a codec is a device or program that compresses data for transmission and dcompresses the received data. In the case of audio, codecs affect your listening experinence, whether you're using headphones,earbuds or Bluetooth speakers 

Mono and Stereo recording

the difference between monophonic (mono) and sterophanic(stereo) sound is the number of channels used to record and playback audio. Mono signals are recorded and played back using a single audio channel, while stereo sounds are recorded and played back using two audio channels. As a listener, the most noticeable difference is that stero sounds are capable of prodcuig the perception of width,whereas mono sounds are not

Compressed files

Advantages

Their size which is about 1/10 the file size of data CD's

small file format because files are so small, they can be easily distrubed over the internet, and huge libaries stored on computers or handheld devices and because of this they can become the consumer standard for purchasing music

easy to convert WAV or CD to MP with free software

compresses files with small difference to the overall sound quality

Disadvantages

to compress the file audio quality is then sacrificed through its very MP3 encoding is not perfect 

compression can result in odd audio "artefacts" that are dertrimental to audio quality particularly to higher frequencies

This audio inaccuracy means that the MP3 are not suitable for pro audio work. In addition many DJ's make sure that they use only higher quality 320kps files, as big sounds systems will tend to make lower rate files sounds and lower rate

Uncompressed audio files

advantages

promises a better listening experience than any other streaming service on the market 

remains when the same when it records

the quality of the digital audio remains intact as it's unchanged 

disadvantages

File size as your music take up a lot of space if you store it all uncompressed and unless you plan on editing the audio 

some of the data is unnecessary and this is where lossless compress in 

Lossless audio files

advantages

no loss of quality

slight decreases in file sizes

Disadvantages

larger files than if you were to use lossy compression.

Lossy Compression

advantages

lots of tools

lots of software

lots of plugin

disadvantages

quality degrades with a higher ratio of compression

can't get back to original after compression

 

Microphone types, accessories, mounts, applications and placement

 

mono microphone

single microphone element.

The microphone element is normally placed at the back of a barrel

has connection vents on both sides

 

Condenser

microphones are commonly used for studio recording

especially on vocals and instruments such as acoustic guitar or piano

good condenser mic can pick up much more tonal variation and nuance than most dynamic microphones.

but they also tend to cost more and more fragile.

they pick up more sonic detail than dynamic mics, condensers require special handling

 

 

RF Condenser

they fulfil the very highest demands on sound quality and versatility and are renowned for their high quality, highly accurate sound reproduction, ruggedness, all weather operation wide frequency response and extremely low inherent self noise

 Electret condenser

variation of the condenser microphone

Instead of requiring an external voltage source to change the diaphragm, an electret microphone uses a permanently charged plastic element (electret) placed in parallel with a conductive metal black plate

 Dynamic

can capture loud sounds without distortion which makes them useful for projecting vocals over a band, or milking drums or guitar amps. when used properly, 

they can add presence or edge to the sounds they pick up. They're built for physical demands of live performance, so they're less likely to break then other microphones. 

A good general purpose dynamic mic like the Classic SM58 and starts around $100

Ribbon Mic

actually a type of dynamic microphone, instead of a dynamic microphone's diaphragm, that is attached to a moving coil that vibrates within a magnetic field, ribbon mics feature on extremely thin strap of metal suspended in a strong magnetic field

advantages of a dynamic condenser mic 

they are cheap

do not require a power source to run

provide good sound quality in all areas of microphone performance

rugged and able to handle high sound pressure levels like those delivered by a kick drum

disadvantages of a dynamic condenser mic

lower sensitivity and power output

slower response time

not the best choice for maximum audio quality

large and heavier

advantages of a condenser mic

more sensitive

better audio quality

can be extremely small

disadvantages of a condenser mic

higher self-noise

more fragile

more expensive

prone to weather problems RF interference    

Pick Up Patterns

the omnidirectional microphone picks up sound in every direction the font the back and the side.

this microphone is good if the sound source comes from a variety of directions and is moving from one side to another in front of the mike.

The cardioid or omnidirectional microphone picks up sound primarily in a heart shape from the front of the microphone including little from the sides but doesn't pick up from the back. This pickup pattern is excellent for voice mikes and making musical instruments 

The hypercardioid ,microphone picks up only sound from the front and is very directional

excellent fr isolating sound sources like bird calls,individual actors taking in a drama or isolating one voice in a sea of voices

The bidirectional microphone picks up sound from two distinct sides of the mike. You would use a mike with this pickup pattern primarly to record two voices talking into the same microphone  

stereo microphone have two microphone element and are designed to give you a wider more immersive sound field than mono microphones

wide pickup pattern is preferable for most live events and when shooting outdoors e.g. radio microphones

Mount

Floor stands

Table Stands

Camera Mounted

 Lavalier                                                                                                                                                        

Boom/dolly mounted

Windshield

Unit 25- Sound recorders,Connectors and Connecting procedures

Types of sound recording set ups

Portable/Battery operated

(Field/Location recording interior and exterior, custom recorders)

Studio/Mains operated application

(Studio recording recording software for computers)

Field Recording

used for an audio recording produced ooutside a recording studio, the term applies to the recording of both natural and human produced sounds. 

The sound recorder used is called Digital recorder

Lavalier microphone is the best type 

Location recording

act of making a high quality complex audio recording of a live concert performance or any other location recording that then uses multitrack recording techniques outside of a recording studio.This is good as it can be recorded place or another time.

Examples

Audacity

GarageBand 

Logic

Pro-x

These softwares are very good especially Audacity it is the easiest one to use

recroding level measurement

VU meter measures db and can also help with tune in vocals

VU meter displays the average level of an audio signal

PPM displays the volume level at a peak

for a steady state stine tone, the differene between

Frequency repsonse defines the range of sound that a microphone can reproduce amd how it's output varies within that range. This frequency and how it's output varies within that range. The frequency response  is the most siginifcant factor in determining the sound signature of a microphone.

Mono Jack

guitars and amplifiers

Stereo Jack

guitar amp

RCA Phono plug

gets a stereo signal

attached in pairs

video input and output

3 xlr

Microphones 

di boxes

tracking of the sound

most connection on one end

Speakon Connector

connecting speakers to amplifiers

scrudulous connections

Problems with recording outdoors is that it creates a load of muffle and if you don't have a dolly it will be harder as it will be poor sound. Another problem would be permission and being able to use th person's voice. Buy a muffler as wind will effect

ambient sound it will be for an omnidirectional as this helps to pick up audio in all directions

Reverb

(short for reverbnation) is the acoustic environment that surrounds a sound. Natura; reverb exists everywhere, whether tje space that is being described is a bathroom or a gymnasium, the essential characteristics remain the same.