AcousticsAcoustics 1 - sound and energythe physics of sound-what is sound?sound is an energy created by vibrations that travels periodically through a medium and this is when the vibrations causes movement in the air particles and then these particles bump into more particles close to them this causes them to vibrate and bump into more particles, they carry on doing this till they run out of energy this reaction is called sound waves and if your ear is in range of the vibrations you will hear the sound. This reaction is similar to the waves created when water is disturbed, picture a stone falling into a still body of water and the ripples it makes this is similar to when a sound is made, and so we use the term sound wave.

when the vibrations are fast you hear a high note and when the are slow you hear a low note.

How do musical instruments work?most musical instruments require two basic elements, a generator which get the vibration going which is needed to create sound and a resonator which amplifies and modifies the sound of the instrument.Guitar - before a guitar string is plucked its in a stable state, when the instrument is played by pressing down on the strings and plucking it and this causes the string to be stretched and then released this causes them to vibrate because the string is trying to get back to its previous state but its moving to fast to stop so it stretches itself in the other direction and this will repeat till it runs out of energy and this energy is lost because its pushing air out of the way.the strings dont move in a perfect curve and if they did you would hear its fundamental frequency which is the lowest frequency that object can make but for this to happen we would have to start from a curve.

However we are starting from a straight line and so when plucking all parts of the string will race off with energy and the same time but not from the same place and this causes the strings from slowly swinging to and fro and wiggling up and down and this is how a complex waveform is created.different sounds are created by where the guitar is plucked so if the string is short it will vibrate at a higher frequency and depending on the thickness of the string, the thicker the string the lower the frequency.

Tom drum- sound in the drum is caused by vibrations or a movement created by force some of the vibrations cause the air to move and creates the sound wave we hear, so sound from the drum is created when the drum head is struck this causes the drum head to get pushed down and then the drum head then vibrates back and forth and this is amplified as they echo throughout the hollow chamber.the pitch of the sound relies on how fast the object vibrates the volume of the sound depends on the amount of force we apply.

flute- the mouth hole where the players breath is directed and when the breath meets the edge it divides into two separate air streams and this creates a rapid vibration at the head of the tube.

Once the air in the flue is vibrating this energy is radiated as sound and this comes out at the end or through any open holes the rest of the tube is the resonator the amplifies and modifies the sound. To change the pitch of the flute you lift up fingers or cover more holes. to make the tone louder you need a larger air flow and to make the tone softer its the opposite.Sound in airsound waves - sound waves are longitudinal waves the must pass through a medium like air, they look like stretched springs. The vibrations are in the same direction as the direction of travel. and a compression is a region in a longitudinal wave where the particles are closest together, a rarefaction is a region is the wave where the particles are further apart.

A sound wave is a visual representation of what is really an outwardly pulsating sound bubble.

Wavelengths - The wavelength in a longitudinal wave is the distance between two consecutive points like to each compression. Each frequency has its own Wavelength. High frequencies are more easily absorbed than low frequencies

Speed of sound - the speed of sound varies in the air itself and is not dependent on amplitude, frequency or wavelength but speed of sound at sea level is 340.29 m/s.the speed of sound changes in different temperatures, this is a good thing for musicians to know as they can change up the sound of there instruments by changing the temperature.Reverberation/Echo - An echo is produced inside a large hall, the sound bounces back from the walls of the structure and this sound reflected back is known as the echo. The amplitude of the echo is always lower than the original sound. the echo can also create a secondary echo from bouncing off other walls. An echo is usually clear and understandable so if to say you said a sentence and it echoed you would understand what it meant. Reverberation is caused by overlapping of multiple echoes, reverberation is also known as reverb and a reverb is not going to be as clear as the original sound, reverb is usually experienced in closed spaces.Soundsound energy- sound energy is omnidirectional so sound moves away from a sound source with equal energy in every direction. a microphone can be omnidirectional and will pick up sound from all around it, in all directions.-pitching forks : When Pitching Forks vibrate they create regular periods of high and low pressure. These are known as the compressions and rarefactions of the air molecules, and will produce a frequency-Frequencies : Frequency describes the number of waves that pass a fixed place in a given amount of time. One compression with one rarefaction is called a cycle. The number of these cycles that occur within one second is called frequency. Frequencies are measured in Hertz. Nearly everything we hear is a complex combination of multiple frequencies. The frequency of a wave is the number of waves produced by a source each second. It is also the number of waves that pass a certain point each second. The unit of frequency is the hertz (Hz). -frequency spectrum : Our frequency spectrum which is the perfect human hearing range from the lowest pitch to the highest is 20 Hertz (Hz) to 20,000 Hertz (20KHz). This range diminishes over time.Acoustics 2 - The Brain - complex waveformshuman hearing-As music technologist if we're exposed to high levels of sound we could get an injury of the ear called tinnitus this causes us to hear a constant ringing or rumbling you could even get deafness or partial deafness also caused by explosion of high levels of sound is can also occur through age often this could effect the clarity of sound or loss/reduced hearing

-How do we hear : Sound waves travel into the ear canal until they reach the eardrum. The eardrum passes the vibrations through the middle ear bones or ossicles into the inner ear. The inner ear is also called the cochlea. Inside the cochlea, there are thousands of tiny hair cells. Hair cells change the vibrations into electrical signals that are sent to the brain through the hearing nerve. The brain tells you that you are hearing a sound and what that sound is. Each hair cell has a small patch of stereocilia sticking up out of the top it. Sound makes the stereocilia rock back and forth. If the sound is too loud, the stereocilia can be bent or broken. This will cause the hair cell to die and it can no longer send sound signals to the brain. In people, once a hair cell dies, it will never grow back. The high frequency hair cells are most easily damaged so people with hearing loss from loud sounds often have problems hearing high pitched things like crickets or birds chirping. We need both ears to hear well, and to tell our brain where the sound is coming from.Psychoacoustics-psychoacoustics : This is the scientific study of sound perception so how we perceive sound so as a sound passes below the threshold of 16hz we stop hearing tone and start hearing a beat and when two tones are slightly different in frequency and have just about the same amplitude this will create an effect of a repetitive volume surges this shows thats beats are a result of the ears ability to separate closely pitched notes.The term psychoacoustics is what we use to explain our response to everything we hear it's one of the biggest factors in acoustic concerns because it's our only response to sound in our environment that the brain thinks fundamentally matters.-envelope : Envelope is a crucial characteristic of a waveform ADSR (attack, decay, sustain, release.-sound in space : Sound travels by making molecules vibrate. So, in order for sound to travel, there has to be something with molecules for it to travel through. On Earth, sound travels to your ears by vibrating air molecules. in deep space, the large empty areas between stars and planets, there are no molecules to vibrate. There is no sound there.-Auditory illusions : is a illusion of hearing, much like visual illusions the brain is capable of performing auditory illusions. The listener hears either sounds which are not present.-sound localization : Is the location or origin of a detected sound in direction and distance this happens though very slight differences in sound intensity and timing to allow us to determine where a sound has come from. -auditory masking : occurs when the perception of a sound is affected by the presence of another sound and the brain can appear to cancel out a sound when something louder comes along..-cocktail party effect : the cocktail party effect is when we have the ability to focus on one sound or one person when there are other background noises/conversations. -how do we tell instruments apart? : many instruments can generate the same frequencies but the shape and material of the instrument will effect the frequencies it produces (most notably the harmonics). The envelope of an instrument will also allow us to differentiate one instrument from another. -Equalization : is a piece of software that will let us control the amplitude of various frequencies this allows us to correct specific problems in a recording of a mic or and instrument this allows contrasting sound to blend together better in a mix. you can alter a sound purley for musical or creative reasons

Acoustics 3 - what is music?-what is a musical note? : A musical note is a repeating cycles of frequency . Noise on the other hand is a complex amalgam of the ripples caused by the disruption of air molecules.Recording studio designWhen designing a recording studio the bigger the room the better this allows more musicians to fit in a room and a place to fit all the gear and it sounds better. Chose the quietest room as when recording you forget how much everyday noise there is and when its recorded in a microphone is amplified and this will ruin your recording.To stop unwanted nose from getting in your recordings soundproofing a room is a good way, it blocks outside noises from coming in and inside noises from going out and it makes your recording sound better by absorbing excessive ambience, this will stop reverberation which is caused by the direct signal reflecting off surfaces, so a very reflective surface would mean less energy absorbed and the reverb time would last longer. To soundproof a room you need to add mass/density like adding material to the walls or if building from scratch use many layers.

To make a better recording having hard flooring and adding bass traps and acoustic panels to a room will absorb low and high frequencies but too much absorption can be bad for mixing purposes.

Parallel walls in a studio can cause standing waves in a recording these happen when sound is reflected back along its own path causing phase differences to interfere with a rooms amplitude response. To stop this from happening you can change the shape of the room.