Chris Degman
Modern Recording Techniques                              
i.	The Recording Studio
•	The commercial studio is made up of one or more accoustic spaces that are specially designed and tuned for capturing the best possible sound on a recording medium.
•	These facilities are sound isolated, to keep outside noise out, and inside noise in, also called soundproofing. 
•	The most important characteristics of these facilities include:
1. A professional staff
2. Professional equiptment
3. Professional, yet comgortable working environment
4. Optimized acoustics and recording environment
5. Optimized control room mixing environment
•	Studios are designed according to the "designer" or reflects the personal taste of the owner, and these designs include:	
1.	A studio that records a wide variety of music (ranging from classical to rock) might have a large main room with smaller, isolated rooms off to the side for unusually loud or soft instruments, vocals, etc.
2.	A studio designed for orchestral film scoring might be larger than other studio types.  Such  a studio will often have high ceilings to accommodate the large sound buildups that are ofter generated by the large number of studio musicians.
3.	A studio used to produce audio for video, film dialogue, vocals and mixdown might consist of only a single, small recording space of the control room for overdub puposes.
     ii.       The Control Room 
•	A recording studio's control room is usually acoustically isolated from the sounds that are produced in the studio as well as surrounding areas, and serves a number of purposes such as:
1.	A critical listening environment that uses specifically placed monitor speakers
2.	It houses the majority of the studio's recording, control and effects-related equiptment
•	The recording console is at the heart of the control room (also referred to as the board or desk) and can be thought of as an artist's palette for the recording engineer, producer, or artist.
•	The console allows the engineer to combine, control and distribute the input and output signals of most if not all of the devices found in the control room, and allows the engineer to blend the mix of amplitude and signals between channels.
•	Tape machines might be located in the rear of the control room where as digital audio workstations (DAW's) are often located to the side of the console or at the functional center if the DAW serces as the room's main recording or mixing device.
iii.    The changing faces of the music studio business
•	The role of the professional recording studio has begun to change and thus there has been an upsurge in project studios, causing professional studios to change their operational business strategies, often met with some degree of success, these changes include:
1.	Personal production and home project studios have greatly reduced the need for an artist or producer to have constant and costly access to a professional facility. As a result, many pro studios now cater to artists, or project studio owners who might have a need for a larger space or better equipped recording facility (for string overdubs or orchestral sessions). 
2.	Upsurges in the need for audio for video and film postproduction have created new markets that allow professional recording studios to provide services to the local, national, and international broadcast and visual production communities. 
3.	A number of studios are also jumping directly into the business of music by offering advisory. business and networking services to artists and bands, sometimes signing the artists and funding tours for a piece of the business pie
•	Studios can no longer afford to put all their eggs in the same media basket, by tapping into the changes in the market forces, and meeting them with new solutions is an important factor for making it.
iv.      The Project Studio
•	One of the greatest benefits of a project or portable production system centers around the idea that an artist can select from a wide range of tools and toys to generate specific sounds.
•	This technology is often extremely powerful and such a system might include, one or more keyboard synthesiszers, synth modules, samplers, drum machines, a computer(with a digital audio workstation and sequencing package), effects devices and audio mixing capabilities.
•	These studios have such cost-effective power and audio fidelity that they can often match the production quality of a professional recording facility, all it takes is knowledge, care, dedication and patience.
  v.      The portable studio
•	As laptops have grown in powe, it has become a simple matter to load them with your favorite Daw software and audio interface, grab your favorite microphones and headphones, and put them in your backpack and hit the road running.
•	Such a system is literally powerful enough to let you compose produce and mix in the studio, or on the beach of a remote seaside island under battery power.
vi.    Knowledge is power
•	In addition to personal drive and passion, the most crucial aspect to putting to gether a high quality or cost effective project studio requires knowledge, and this can be gained by:
1.	Reading about the equipment choices that ae available to you on the web or in the trade magazines
2.	Visiting and talking with others of like(and dissimilar) minds about their equipment and personal working styles
3.	Enrolling in a recording course that best fits your needs, working style and budget
4.	Getting your hands on equipment before you make your final purchases (for example, checking out the tools and toys at your favorite music store)
5.	Experience, always the best teacher
vii.       Whatever works for you
•	There are hundreds, if not thousands, of choices for recording media, hardware types, software systems, speakers, effects devices, and more.
•	When working with art(even the business of art), there are many choices to combine to make the perfect fitting working environment for you, such as:
1.	Work with a hard disk or tape based system
2.	Choose to use analog or digital (or both)
3.	Are a Mac or PC kind of person (practically a non issue these days)
4.	use this type of software or that...
viii.        Making the project studio pay for itself
•	Other than being able to record when, where, and how you want in a project studio, there are other benefits to working in a personal environment, here are examples of how a project studio could subsidize itself:
1.	Setting your own schedule and saving money while you're at it. Being able to record when and where you want, at any given moment such at practice tracks, or when the mood hits, instead of punching a pro studio's time clock, having to be ready to go at a specific moment, or date.
2.	Being able to write off equpment, building or utilities payments as a tax deductible.
3.	An individual artist, or group might want to preproduce a project in their own project studio, these times and expenses could also be tax deductible
4.	These same artists could want to record all of a project in their project studio and the time or money saved, or deducted, could be spent on a better mixdown facility, production, legal, or marketing.
5.	The signed artist/superstar approach refers to the mega artist who, instead of blowing the advanced royalties on lavish parties, they invest in their own professional grade project studio, after a project has been finished, they will have a tax deductible facility that can be operated as a business enterprise, and when the next project comes along, the artist will still have a personal facility in which to record and can put the advance bucks in the bank.
ix.        Live/on location recording: A different animal
•	Unlike multitrack recording, where overdubs are often used to build up songs over time, live/on location recordings are created on the spot, in real time, or during a single on stage or in the studio performance, with little or no studio postproduction other than a  mixdown.
•	More elaborate live recordings might require the use of a temporary control room or fully equipped mobile recording van or truck that could record to hard disk or tape.
•	A more involved set up would  require a great deal of preparation and expertise, including a combined knowledge of the sound reinforcement and live recording techniques that are necessary to capture instuments in a manter that has enough isolation between tracks, to yield the highest degree of control during mixdown, and still have the live feel.
        x.           Audio for video and film
•	With (MTS) multichannel television sound, and dvd and blu ray surround sound, audio has matured into a respected part of film and vidio media production.
•	MIDI, hard disk recording, timecode, automated mixdowns and advanced processing have become a part of the everyday components of the audio environment.
xi.    People who make it all happen
•	The Artist
1.	The strength of a recorded performance begins and ends with the artist
•	Studio musicians and arrangers
1.	An entire group of studio musicians might be called on to provide the best possible musical support for a high profile artist or vocalist
2.	A project might require musical ensebles (such as a choir, string section or background vocals) for a particular part or to give a piece of fuller sound
3.	If a large ensemble is needed it might be necessary to call in a professional music contractor to coordinate all of the musicians and make the financial arrangements, the project might require a music arranger, who can notate and possivly conduct the carious musical parts
4.	A member of a group might not be available or be up to the overall musical standards that are required by a project, in such situations it's not uncommon for a professional studio musician to be called in.
•	The Producer
1.	Assists in the selection of songs
2.	Helps to focus the artistic goals and performance in a way that best conveys the music to the targeted audience
3.	Helps to translate tha performance into a final salable product (with the technical and artistic help of an engineer and mastering engineer)
•	The engineer
1.	conceptualizes the best technological approach for capturing a performance or music experience
2.	Documents the process for other engineers for future production use
3.	Places the musicians in the sesired studio positions
4.	Choose and place the microphones
5.	sets levels and balances on the recording console or Daw mixing interface
6.	Records the perfomance onto a dard disk or tape
7.	Overdubs additional musical parts into the session that might be needed at a later time
8.	Mixes the project into a final master recording in any number of media and mono, stereo, and surround sound formats
9.	Helps in meeting the needs for acheicing and/or storing the project
•	The Assistant engineer
1.	An engineer in training that might be able to assist the audio engineer
•	Maintenance engineer
1.	Maintains the equipment, makes sure everything is in top shape
•	Mastering engineers
1.	Sometimes the final master will need to be tweaked in level, EQ, or dynamics, to present the final recording in the best possible sonic and marketable light.
•	The DJ
1.	On the air: The dh of the airwaves is still a very powerful voice for getting the word out about a particular musical product
2.	On the floor: This dj form often reinforces the messages from the airwaves or helps to promote the musical word in the mainstream and counter cultural music environments
3.	On the web: Probably one of the more up and coming voices for getting the promotional word out to a large number of specially targeted audiences
•	The vj
1.	The vj is important for bands who like to use music videos on web bassed or on stage performances.
         xii.         Studio Management
•	Management: the studio manager, who might or might not be the studio owner is responsible for managerical and marketing decisions
•	Bookings: this staff person keeps track of most of the details relating to the studio usage and billing
•	Competent secretarial staff: These assisstants keep everyone happy and everything running as smoothly as possible
xiii.       Music Law
•	It is never good for an artist, band, or production facility to underestimate the importance of a good music lawyer, when entering into an important business relationship, it is always a good idea to have a professional ally who can help you, your band or your company navigate throught the treacherous waters  
xiv.     Behind the scenes
•	Without many facets of music business-technology, production, distribution and law, the music biz would be very different, a small sampling of the additional professional fields that help make it happen include:
1.	Artist management
2.	Artist booking agents
3.	A&R (Artist and repertoire)
4.	Manufacturing
5.	Music and print publishing
6.	Distribution
7.	Web development
8.	Graphic arts and layout
9.	Equipment design
10.	Audio company marketing
11.	Studio management
12.	Live sound tour management
13.	Acoustics
14.	Audio instruction
15.	Club management
16.	Sound system installation for nightclubs, airports, homes ect.
17.	....And a lot more  
xv.         Career Development
•	It's a sure bet that those who are interested in getting into the business of audio will quickly find out that it can be a tough nut to crack. For every person who makes it, a large number won't.  So how do you get to the front of the line? Well here is the key:
1.	A ton of self motivation
2.	Good networking skills
3.	An ongoing and open willingess to learn and experiment
•	A good time to start making your dream career starts NOW. Don't wait for it to fall into your lap, go out and make it happen, some tips on how to get started are as follows:
1.	Choose a mentor (sometimes they fall from the sky, sometimes you have to develop the relationship)
2.	Contact companies in your area that might bbe looking for interns
3.	Use your school counselors for intern placement
4.	Pic the areas you want to live in (if that is a factor)
5.	Pick the companies and area that you are interested in and target them
6.	Visit or send resumes or electronic press kits (EPK's) to companies or studios that interest you
7.	Send out lots of resumes
8.	Make a personal web page and a myspace or facebook page
9.	Follow up with a phone call
10.	Visit these companies just to hang out and see what they are like
11.	Follow up with another phone call
xvi.        The recording process
•	In this age of pro studios, project studios ect., it's easy to see how the adage " different strokes for different folks" applies to the music biz, it will vary per person, or company, with the different choices in equipment ect., but if we put that aside, the process of capturing sound onto a recorded medium will generally occur in 8 distinct steps:
1.	Preparation 
2.	Recording
3.	Overdubbing
4.	Mixdown
5.	Mastering
6.	Song sequence editing
7.	Production manufacturing
8.	Marketing and sales
A.	Preparation:
•	one of the most important aspects of the recording process occurs befor the artist and production team step into the studio, preparation, asking questions like the following must be addressed long before going in the studio:
1.	What is the goal?  
2.	What is the budget?
3.	What are the estimated studio costs?
4.	Will there be enough time to work on vocals, mixing, and other important issues before running out of money?
5.	How much will it cost to manufacture the CD's and/or records?
6.	What are the advertising costs?
7.	How will the music be distributed and sold? And to whom?
8.	Is the group practiced enough?
9.	If the project doesn't have a producer, who will speak for the group when the going gets rough?
10.	Are the istruments, voices and attidudes ready for the task ahead?
11.	Are there any legal issues to consider?
12.	How and when will the website be up and running?
B. Recording
•	The first phase in multitrack production is the recording process.
•	Beyond capturing the best performance and sound onto a recorded media, one of the the ideas within multitrack production is isolation.
C. Overdubbing
•	verdubbing allows instruments and/or vocals to be added at a later time to exsisting tracks on a multitrack recording medium
•	in an overdubb session the same procedure is followed for mic selection, placement, EQ, and level as they occured during a recording session.     
D. Mixdown
•	The mix down process occurs by routing the various tracks of a DAW or tape-based recorder through a hardware or DAW virtual mixing console to alter the overall session's program with Relirespects to:
1.	Relative level
2.	Spatial positioning (the physical placement of a sound within a stereo or sourround sound field)
3.	Equalization (affecting the relative frequency balance of a track)
4.	Dynamics processing (altering the dynamic range of a track, group or output bus to optimize levels or to alter the dynamics of a track so that it "fits" better within a mix)
5.	Effects proccessing ( adding reverb, delay, or pitch related effects to a mix in order to augment or alter the the piece in a way that is natural, unnatural or just plain interesting)
•	once ready the console can be placed into the mixdown mode (or each input module can be switched to the line or tape position) and the fader label strips can be labeled. 
•	The channel and group faders should be set to unity gain (0dB) and the master output faders should likewise be set with the monitor section being switched to feed the mixdown signal to the appropriate speakers.
  E. Mastering
•	Once done, the final, edited mixdown of a project might be sent to a mastering engineer so thatr fine-tuning adjustments can be made to the overall recording with respect to:
1.	Relative level balancing between songs within the project
2.	Dynamic level (altering the dynamics of a song so as to maximize its level for the intended media or to tighten up the dynamic balance, overall or within certain frequency bands)   
3.	EQ
4.	Overall level
          F.  Song sequence editing
•	Whenever the various soundfiles of a project are loaded into a DAW, editor or certain CD burning program, each song or program segment can be tailored in a number of ways:
1.	The start and end points can be located and defined for each song
2.	Each song can be individually processed using EQ, overall level, dynamics, ect.
3.	The proper fades and silence gaps can be entered into the edit session.
4.	The completed master can then be transferred to a CD-R or final mastered media.
5.	Long silences between songs help the listeners get out of the mood of the previous song and prepare them for hearing something that might be quite different.
            G. Product manufacturing
•	Whether the final product is compact disc or digital download, this process should be carefully overseen, these manufacturing phases should be carefully scrutinized, checked, and rechecked:
1.	Creating a manufacture master
2.	Art layout and printing
3.	Product packaging
             H. Marketing and sales
•	The following questions shold be all answered long befor the record button is pressed and the first downbeat is played:
1.	Who is my audience?
2.	Will the project be distributed by a record company, or will I try to sell it myself?
3.	What should be the final product look and sound like?
4.	What's my budget and how much is this going to cost me?
xvii.  The transducer
•	Quite simply a transducer is any device that changes one form of energy into another, corresponding form of energy.
Trandsducer                                     From                                                                                 To
Ear			            Sound waves in air		     Nerve impulses in the brain
Microphone		            Sound waves in air		     Electrical signals in wires
Record head		            Electrical signales in wires	     Magnetic flux on tape
Playback head		            Magnetic flux on tape		     Electrical signals in wires
Phonograph Cartridge	            Grooves cut in disk surface	     Electrical signals in wires
Speaker 		            Electrical signals in wires		     Soundwaves in air
Sound and hearing
•	If we start with the idea that sound is actually a concept that describes the brain's perception and interpretation of a physical auditory stimulus, the examination of sound can be divided into four areas:
1.	The basics of sound
2.	The characteristics of the ear
3.	How the ear is stimulated by sound
4.	The psychoacoustics of hearing
i. The basics of sound
•	Sound arrives at the ear in the form of periodic variations in atmospheric pressure called sound pressure waves.
•	An analogy of how sound waves travel in air can be demonstrated by bursting a baloon in a silent room.
•	The air molecules in the balloon are under pressure and packed in a tight area (like people packed in a subway car), while the molecular motion of the rooms atmophere is at a normal resting pressue, but when the balloon is popped the molecules under pressure exert an outward force onto their neighboring lower pressure molecules. When the neighboring molecules hae been compressed, they will continue to exert force outward onto the next set of molecules, in an ongoing outward motion that continues until the molecules have used up thier energy in the form of heat.
       ii. Waveform Characteristics
•	A wave form lets us see and explain the actual phenomenon of a wave propagation in our physical environment and will generally have the following fundamental characteristics:
1.	Amplitude
2.	Frequency
3.	Velocity
4.	Wavelength
5.	Phase 
6.	Harmonic consent
7.	Envelope
A. Amplitude
•	The distance above or below the centerline of a waveform, such as a pure sine wave, represents the amplitude level of that signal.
B. Frequency
•	The rate at which an acoustic geerator, electrical signal or vibrating mass repeats within a cycle of positive and degative amplitude is known as the frequency of that signal.
C. Velocity
•	The velocity of a sound wave as it travels throuh air at 68oF is approx. 1130 feet per second or 344 meters per second.  This speed is temperature dependent and increases at a rate of 1.1(ft./sec.) for each fahrenheit degree increase in teperature.
D. Wavelength
•	The wavelength of a waveform (frequently represented by the greek letter lambda) is the physical distance in a medium between the beginning and the end of a cycle. ( l = V/f) where lambda is the wavelength in the medium, V is the velocity in the medium, and f is the frequency in hertz.
•	 T=1/f, where T is the numver of seconds per cycle
E.  Phase
•	Because we know that a cycal can begin at any point on a waveform, it follows that whenever two or more waveforms are involved in producing a sound, their relative amplitudes can (and often will) be different at any one pint in time.  Two waveforms that are similar in amplitude and frequency but start their cycles at different moments are considered out of phase.
F. Harmonic content
•	An over tone  is an upper partial or a frequency that is an octive above the funamental pitch
•	Because musical instuments produce sound waves that contain harmonics with various amplitude and phase relationships, the resulting waveforms bear little resemblance to the shape of the single frequency sine wave, so musical waveforms can be divided into two categories: simple and complex. 
•	Square waves, triangle waves and sawtooth waves are examples of simple waces that contain a consistent harmmonic structure.
•	Complex waves on the other hand dont necessarily repeat and often are not symmetrical about the zero line. An example of a complex waveform is one that's created by any naturally occurring sound such as music or speech.
G. Envelope
•	The envelope of an acoustic or electronically generated signal is composed of four sections that vary in aplitude over time:
1.	Attack refers to the time taken for a sound to build up to ists full volume when a note is initially sounded.
2.	Decay refers to  how quickly the sound levels off to a sustain level after the peak
3.	sustain refers to the duration of the ongoing sound
4.	Release relates to how quickly the sound will decay once the not is released.
iii. Loudness levels: the decibel
     A. Logarithmic basics
•	All that's really important to help you along are three simple guidelines:
1.	The log of the number 2 is 0.3
2.	When a number is an integral powe of ten, the log can be found by simply adding up the number of zeros
3.	Numbers that are larger than one are positive log values, while numbers below one are negative log values
             B. The decibel
•	The decibel is a logarithmic value that expresses differences in intisities between two levels, most common form  being sound pressure level, voltage and power in watts.
Sound-pressure level
•	Sound pressure level is the acoustic pressure that is built up withing a defined atmopheric area, usually a square centimeter or cm2
•	We can arrive at an spl rating by using the formula:
dB SPL=20logSPL/SPLref 
Voltage
•	Voltage can be thought of as the pressure behind electrons within a wire. As with acoustic energy comparing one voltage level to another level can be expressed as dBvv using the equation:
dBv=20logV/Vref
where V is the voltage, and Vref is the reference voltage (0.775 volts)
Power
•	Powe is usually a measure of wattage or current and can be thought of as the flow of electrons through a wire over time. Unlike SPL and voltage, the equation for signal level whis is ofted expresssed in dBm is:
dBm=10logP/Pref
Where P is the measured wattage, and Pref is referenced to 1 miliwatt(0.001 watt)
     C. The simple heart of the matter
•	The basic concepts of using the unit of power are:
1.	A 1-dB change is barely noticeable to most ears
2.	Turning something up by 3 dB will double the signal's level, (believe it or not doubling the signal level won't increase the perceived loudness as much as you might think)
3.	Turning something down by 3 dB will halve the signal's level ( likewise, halving the signal won't decrease the perceived loudness as much as you might think)
4.	The log of an exponent of 10 can be easily figured by simply counting the zeros. Given that this figure is multiplied by 10 ( 10logP/Pref) turning something up by 10dB will increase the signal's level 10-fold, 20 dB will yeild a 100-fold increase, 30 dB will yeild a 1000-fold increace, etc.
iv. The ear
•	There are four main parts of the human ear, the pinna, the outer ear, the eardrum, and the conchlea.
A. The Pinna is the part of the ear we can see.
B. The outer ear is the canal to the ear drum.
C. The eardrum is a stretched out membrane where sound waves are changed into mechanical vibrations, which are transferred to the inner ear by the way of three bones, the hammer, the anvil, and the stirrup.
D. the conchlea is a tubular snail like organ what contains two fluid filled chanbers liked with tiny hairs.
Threshold of hearing
•	In the case of SPL, a convenient pressure level reference is the threshold of hearing, which is the minimum sound pressure that produces the phenomenon of hearing in mosp people and is equal to 0.0002 microbar. One microbar is equal to 1 millionth of normal atmospheric pressure.
Threshold of feeling
•	An SPL that causes discomfort in a listener 50% of the time is called the threshold of feeling, it occurs at a level of about 118 dB SPL between the frequencies of 200Hz and 10kHz
Threshold of pain
•	The SPL that causes pain in a listener 50% of the time is called the threshold of pain and corresponds to an SPL of 140 dB in the frequency range between 200Hz and 10kHz
Taking care of your hearing
•	There are different types of hearing loss which are:
1.	Acoustic trauma: this happens when the ear is exposed to a sudden, loud noise in excess of 140 dB. Such a shock could lead to permanent hearing loss.
2.	Temporary threshold shift: The ear can experience temporary hearing loss when exposed to long-term loud noise.
3.	Permanent threshold shift: extended exposure to loud noises in a specific or broad hearing range can lead to permanent hearing oss in that range. In short, the ear becomes less sensitive to sounds in the damaged frequency range leading to a reduction in perceived volume.
•	Here are a few hearing conservation tips that can help reduce hearing loss due to long term exposure of sound over 115 dB:
1.	Avoid hazardous sound environments; if they are not avoidable, wear hearing protection devices such as foam plugs or in ear monitors
2.	Monitor sound pressure levels at or around 85 dB
3.	Take 15 minute quiet breaks every few hours if youre being exposed to levels above 85 dB.
4.	Musicians and other live entertainment professionals should avoid practicing at concert hall levels whenever possible
5.	Have your hearing checked by a licensed audiologist
v. Psychoacoustics
•	The area of psychoacoustics deals with how and why the brain interprets a particular sound stimulus in a certain way.
      vi. Auditory perception
•	It's important to realize that the ear is a nonlinear device, the ear's frequency response(it's perception of timbre) changes with the loudness of the perceived signal.
•	The fletcher-Munson Equal-Loudness contour curves indicate the ear's average sensitivity to different frequencies at various levels. These indicate the sound-pressure levels tht are required for our ears to hear frequencies along the curve as being equal in level.
•	As a result of the nonlinearities in the ear's response, tones will often interact with eachother rather than being perceived as being separate, Three types of interation effects can occur:
1.	Beats
2.	Combination tones
3.	Masking
A. Beats
•	Two tones that differ only slightly in frequency and have approximately the same amplitude will produce an effect know as beats
B. Combination tones
•	Combination tones result when two loud tones differ by more than 50 Hz. In this case the ear perceives an additional set of tones that are equal to  both the  sum and the difference between the  two original tones, as well as being equal to the sum and difference between their harmonics, the simple formulas for computing the fundamental tones are:
Sum tone=f1+f2
Difference tone=f1-f2
D. Masking
•	Masking is the phenomenon by which loud signals prevent the ear from hearing softer sounds, the greatest masking effect occurs when the frequency of the sound and the frequency of the masking noise are close to each other.
vi. Perception of direction
•	Allthough one ear can't discern the direction of a sound's origin, two ears can. This capability of two ears to localize the sound source within an acoustic space is called spatial, or binaural localization, this effect is the result of three acoustic cues that are recieved by the ears:
1.	Interaural intensity differences
2.	Interaural arrival-time differences
3.	The effects of the pinnae ( outer ears)
vii. Perception of space
•	When a sound is generated, a percentage reaches the listener directly, without encountering any obstacles. A larger prtion, however is propagated to the many surfaces of an acoustic enclosure, if these surfaces are reflective, the sound is bounced back into the room and toward the listener, if the surfaces are absorptive, less energy will be relfected back to the listener, three types of reflections are commonly generated within an eclosed space:
1.	Direct sound
2.	Early reflections
3.	Reverb
A. Direct sound
•	When sound travels through air, it's at a constant speed of about 1130 feet per second, so a wave will follow the shortest path to the listener.
B. Early reflections
•	Early reflections give us clues as to the reflectivity, size and general nature of an acoustic space.
C. Reverberation
•	Whenever a room reflections continue to bounce off of room boundaries a randomly decaying set of sounds can often be heard after the source stops in the form of reverberation.
viii. Doubling
•	By repeating a signal using a short delay of 4 to 20 msec, the brain can be fooled into thinking that the appparent number of instruments being played is doubled.