331 Royalty-Free Audio Tracks for "Rise"

Effects recorded from the field of the zoom h6 recorder,and microphone oktava mk-012-01,and then processed. Sound composed of several layers, and then processed with different effect plug-ins in: cakewalk by bandlab. I use software to produce effects:cakewalk by bandlabreaktor 6audio editor wavosaur.

Effects recorded from the field of the zoom h6 recorder,and microphone oktava mk-012-01,and then processed. Sound composed of several layers, and then processed with different effect plug-ins in: cakewalk by bandlab. I use software to produce effects:cakewalk by bandlabreaktor 6audio editor wavosaur.

Effects recorded from the field of the zoom h6 recorder,and microphone oktava mk-012-01,and then processed. Sound composed of several layers, and then processed with different effect plug-ins in: cakewalk by bandlab. I use software to produce effects:cakewalk by bandlabreaktor 6audio editor wavosaur.

Effects recorded from the field of the zoom h6 recorder,and microphone oktava mk-012-01,and then processed. Sound composed of several layers, and then processed with different effect plug-ins in: cakewalk by bandlab. I use software to produce effects:cakewalk by bandlabreaktor 6audio editor wavosaur.

Effects recorded from the field of the zoom h6 recorder,and microphone oktava mk-012-01,and then processed. Sound composed of several layers, and then processed with different effect plug-ins in: cakewalk by bandlab. I use software to produce effects:cakewalk by bandlabreaktor 6audio editor wavosaur.

Effects recorded from the field of the zoom h6 recorder,and microphone oktava mk-012-01,and then processed. Sound composed of several layers, and then processed with different effect plug-ins in: cakewalk by bandlab. I use software to produce effects:cakewalk by bandlabreaktor 6audio editor wavosaur.

Five is four: a polyrhythmic analog-synth loop with ambiguous five or four time signature. Slightly frantic sounding, arpeggiator-like rising pattern a bit like a shepard tone, it's a 5/4 pattern, but accents are distributed in 4/4. 180 bpm, key is a-minor (a-minor then f-major). Two loops marked in wav file, first is the bare synth pattern, loop is samples 0 to 640,000; second is with a pad, loop is samples 960,000 to 1,600,000.

I did a two week artist residency at paradise air (http://paradiseair. Info), in matsudo, chiba, japan. I recorded a lot of sounds in the area, and edited them into a series of thrilling sound effects.

Composed in musescore, synths added with lmms, additional sound done with audactiy. Starts out with bass drums, progresses to synths held on one note, then snares. Double bass creates rising tension. For bone-clicking sound effects, i just shook a handful of pencils. Cymbals at the end for final climax of the sound. Sound design originally for use by twoallnighters comic dub studio on youtube. Released to general public with permission of its creator.

The morning after christmas 2022 on hood canal. There was a king tide that came up over the stone wall. A king tide occurs when the sun, moon, and earth are in alignment and the combined gravitational pull causes water levels to rise dramatically. I took this recording right next to the pilings where the dock is connected. You can hear the water hitting the metal and wood as it knocks it around. The water eventually washed over the road.

Same patch as in electronic minute no 226 and 227 but on my real modular. I'm using a filter. Thats why i call this version subtractive. I'm subtracting harmonics from a square wave. Why are 226 blue? probably because i did it at work. . . Listening in bad earbuds. Makes you rise the bass. Lets see if i can make this wave ble at the end! i will slowly fade out the vco with high pitch. At the very end i'm switching the synth off.

I wanted to make a very gentle wakeup alarm for my android phone. It's a 25-minute long fade in of a pure 3-khz tone. Created with audacity. I encoded this to ogg vorbis for personal use, but i'm sure you can do this better for yourself (maybe you'll prefer other format), so here you have a quality flac file for source.

Sound design elements. Effects recorded from the field of the zoom h6 recorder,and microphone oktava mk-012-01,and then processed. Sound composed of several layers, and then processed with different effect plug-ins in: cakewalk by bandlab, pro tools first. I use software to produce effects:ableton livecakewalk by bandlabreaktor 6vcv rack 0. 6. 0pro tools firstaudio editor wavosaur.

What effects the color of the wave here on freesound? i could ask, but here is a little test. Part 1 - a (about) 60hz tone going from sinus to triangle (vcv-rack vco-2)part 2 - same tone. Sinus wave. An accelerating vibrato. Part 3 - now 2 tones. Same 60hz sinus tone plus another sinus tone slowly increasing in frequency creating beating effects. The second, rising, vco has a lower amplitude. All three part has the same peak amplitude (-4db)#colortest.

This wood thrush was recorded around 7:30 in the morning in heavy woods in deep southern illinois. Unlike my earlier posting of the wood thrush singing at dusk, this morning recording has the wood thrush singing with lots of company, although he clearly rises above his neighbors. 17 seconds into the recording you hear the drumming of a woodpecker, and at one-minute 20 seconds into the recording you hear the distinctive-lonely sounding call of the huge pileated woodpecker. Recording made with good-quality stereo microphones so use headphones to get a wonderful experience.

Electronic minute no 30 - 8 tones and tempo change. A patch centered around intellijel quadra + expanderim using the quadra modea sloth lfo is affecting the rise on one envelope generatorjoined eoc triggers sequencera slew, filter and some fm-generated vibratoand i patch up a pan fuctionyou know lfo + two vcas + and inverter. . . I want a vc pan moduleits on my lista little spring reverb as always. Evaluation of patch/soundone cycle is - there are many cycles to consideronly short sounds - no, goodamplitude variation - yep goodpitch variation - controlled by sequencertimbre variation - some, via filtermusical value - maybeentertaining - hmm. . . Interesting.

Soundtrack guitar theme. Suitable for intro. I imagine this guitar theme as an intro for a film about skaters, surfers. A scene with the rising sun in an urban city. Of course, you can imagine and use it for a scene that suits you. I can extend this theme as needed. Contact me for that. If you use this sample you >>>must<<< write my name (mareproduction) as a author of this sample and link to this page. If you like what you hear please consider a small amount (even one dollar is enough) of donations to support my work. Thank you!. Paypall:jazzgitara@gmail. Com.

A short recording of construction work on a ten-storey apartment building in the blackhorse road area of walthamstow, london. General construction noises. This recording was made using a sound devices mixpre6ii and a stereo pair of fel em172 mics. Low cut on the sd which in basic mode is 80hz (i think). There is some processing to this recording to ‘normalize’ the levels and light eq-ing. I do not require any credit or attribution. If any of these sounds have been of help, and you are feeling charitable, please do consider donating to freesound to help keep the site running (a link is also on the home page). Any donations are greatly appreciated!.

48khz-16 bit suburban soundcsape from france on a morning in early autumn. Cold rain in the foreground and the odd solitary bird. In the distance, the sound of a destruction team pulling apart buildings mixes with the phasing sound of the ring-road. Listening positions is against a wall facing a open grassy area and about 50 meters a block of flats bounces the sound back to us. Recorded in mono in november 2014 around 11 am with a akg ck91 cardio capsule / wendt 2x / mbox2 in pt. Http://www. Radio1. Pf/cms/wp-content/uploads/2014/08/le-quartier-du-mirail-a-toulouse_scalewidth_630. Jpg />.

Here is another night of that couple next door. They were active for around 25 minutes. Sounds like they had a really good night. The recorded audio of this was over two hours long and edit down to this length. Many of their conversations before they you know and after they finished were excluded out. At 2:32, sounds like the woman said "wanna go ahead,. . . "starting around at 3:45 was when they probably began to have their fun in bed, but there were still bits of soft chit chat between the couple. At 13:25 is when there are bits of moans coming from the woman. At 14:50 is when the rising action really begins. At 25:00 was when their fun was coming to an end, and you should be able to hear some of the noises from the guy. For those who just want the good parts of the audio: 13:25-25:56.

Sound effect - bass rumble tension rise (wind river movie). I've looked for this particular bass tension builder sound effect from the movie wind river since it came out!! if you've seen that film and you're familiar with the "standoff" scene, then you'll probably know what sound effect im referring to. . . In the background of that most intense ever scene of all time is this bass rumble or tension builder that gives me goosebumps every time i watch it! i've wanted the original pretty bad because its the best suspense builder(bass rumble) sound ive ever heard! although it doesn't seem to exist online even for purchase. So i tried to recreate it myself! im a movie scene editor all the way, but im less than amature at audio editing, so please excuse the flaws. There are 3 versions in this mp3. All with different tones, speed, and other details trying to recreate as best i could.

English. 1. With both hands i grabbed the rain stick vertically. 2. Lift it about 4 or 5 cm from the plastic mat on the floor3. I moved it up and then down until it hit a mat. The movement was fast, which causes the internal seeds to rise and fall, hit each other, between the walls of the stick and bounce when hit on the mat. The sound was captured with a condenser microphone. It was recorded with ardour 5. Español. 1. Con ambas manos agarré verticalmente el palo de lluvia. 2. Lo levánte unos 4 ó 5 cm del tapéte de plástico que se encuentra en el suelo3. Lo moví hacia arriba y en seguida hacia abajo hasta golpear un tapete. El movimiento fue rápido lo que produce que las semillas internas suban y bajen, golpearse entré si, entre las paredes del palo y rebotar cuando se golpea en el tapete. El sonido se captó con un micrófono de condesador. Se grabó con ardour 5.

. . Inside an intercity express (ice) between stuttgart and mannheim, sitting in an almost empty (three passengers) second-class broad-spaced compartment at around 9 pm. After a shaky first minute an even part follows for around 90 seconds. Interrupted by some road holes the steady sound continues, now with the frequency of the engine sound rising until the beginning of the fourth minute. Here the "main part" begins, starting with several moments of acceleration, deceleracion and breaking. From minute 5:15 to 7:35 the train reaches it's peak velocity, with only few bumps. After a short deceleration the train inceases velocity again, reaching a second peak, this time noticeably bumpier. Once in a while you can hear some element of the fitments rattling nervously along the track, depending on the constitution of the railways and the overall situation. During the last two minutes the train keeps on decelerating slowly and continuously until the end. Recorded in stereo with a portable stereo recorder (zoom); enhanced in audacity using a parallel dynamic eq (tdr nova), a compressor (vos density mkiii) and a binaural spacializer (auburn panagement).

Modern Music from Psalm Singer's Amusement by William Billings (1781). Lyrics: we are met for a Concert of modern invention To tickle the Ear is our present intention Audience are seated expecting to be treated with a piece of the Best with a piece of the best & since we all agree to set the tune on E the Authors darling Key he prefers to the rest let the Bass take the Lead & firmly proceed till the parts are agreed to... let the Tenor succed & follow the Lead till the parts are agreed to... let the Counter inspire the rest of the choir inflamed with desire to... let the Treble in the rear no longer forbear but expressly declare for a... ...fuge away then change to brisker time & up the Ladder climb & down again the mount the second time & end the strain then change the Key to pen five tones & flow in Treble time the Notes exceeding low keep down awhile then rise by slow degrees the process surely will not fail to please Thru Common & Treble we jointly have run we'll give you their Essense compounded in one all though we are strongly attached to the rest six four is the movement that pleases us best that pleases us best six four is the movement that pleases us best & now we address you as Friends to the cause performers are modest & make their own laws although we are sanguin & clap at the Bang the part of the hearer's to clap their Applause to clap their applause the part of the hearer's to clap their Applause

This is a reading from the second chapter of "nathaniel's nutmeg: or, the true and incredible adventures of the spice trader who changed the course of history", by giles milton. It is also intended for the freesound sound museum to represent books as what is fading rapidly into obsolescence. By the time you read this, you may not even know what a books is. Books are when the written word is compiled onto sheets of paper in a long-form volume. You may not know what paper is. Paper is commonly used to write on or make oregano cranes with, being flat and thin rectangles made from trees. You probably won't remember what a tree was. That is a very sad thing. They are all gone now, destroyed in feckless deference to paper. When the paper runs out, there will be nothing left to write our collective histories on, what we desperately need. When this occurs, it will stand as the moment our past was truly lost, leaving us lost the same, drifting in circles. Until another man or woman rises up to invent trees again, thus beginning the cycle anew. It's a beautiful idea. We should always be moving towards the future, not lost in syrupy memories of old forests not seen for what they really are: petrified wood and amber. Leave that with the other fossils and relics. Let it be the final page written on the last book until it crumbles to dust. Let it go. The file was recorded using a mid/side stereo technique at 24bits, downsampled to 16bits under the loving care of gaussian dither. The room was treated as best i could to be acoustically pleasing and quiet. I think you will find the noise floor to be particularly well balanced and textured, suitable for post-production tasks, or just for relaxing with at home. .

This is a quick fire sound i made using qubodup's "swing 25" public domain/cc0 upload on this site. It's a bamboo stick swinging, which i layered and toyed with to get the results here. For those curious, here are the steps. * i took the file into reaper, and slowed the file's playback rate to 31% of the original. * i then duplicated the file three times, for a total of 4 tracks. * track 1 (lowish gas-burner sound):- reverb (drum-room impulse response, a medium-sounding reverb with a slight deadness to it. In free impulse loader reverberate le, stretched impulse to 150% and set attack time to 0. 218s). - eq (-8db bandpass near 200hz, rising back to 0 by the 1k mark. Low-pass applied at 5. 8khz). * track 2 (lowest of sounds, like a bassy gas-burner):- chorus effect. That's it. (specifically acon digital multiply, a free plugin, set to the "romantic" preset). * track 3 (not as low as track 2, but closer to track 2 than 1)- reverb (a large hall impulse response. No adjustments, ie. No increased attack or stretching like for track 1. ). -chorus doubler (free plugin duet, preset: "basic doubler. " same effect as if i had doubled the track and pitched one up 6 cents. ). - chorus (free plugin acon digital multiply, preset: "romantic. "). * track 4 (most flame-thrower, whooshy of tracks. )- reverb (impulse response says "hall medium," but it's a thick, even echo from start to finish. Makes the sound go from its default "whoosh" to a flamethrower noise. - chorus doubler (duet again, preset: basic doubler). - chorus (acon digital multiply, preset: "romantic. "). Master bus:. - compressor (tdr kotelnikov mastering compressor, the free successor to the tdr feedback compressor ii. Preset: punchy. Thresh: -20. 9, soft knee: -1. 5, ratio: 2:0:1, attack: 7. 0 ms, release peak: 70 ms, release rms: 165 ms, makeup: 1. 5 db, output: 2. 0 db. That's it.

Hi. This soundfile was recorded on 03. 06. 2017 in szczecin, nw poland (gumience district to be precise). The time of this recording is from around 3 a. M. (when the sun was allready rising) till around 7:30 a. M. What's funny about that, is that i turned my recorder on and layed it on the windowsill (display up) on altitude around 5 meters (first floor), (the recorder is facing ne direction) because the birds were allready going crazy!, and after some time i felt asleep, and the recorder was left on. There are many many kinds of birds around, cause there is a big cementery near by, with lots of trees, and some wild fruit orchard too. I had this one moment, when the birds were so active, that let's say they spinned it me around, and worked me up to a beautifull spiritual moment with their sounds, and then i felt asleep. Later through the recording you can hear me snoring, you can hear my alarm clock going on (and that haven't woken me up too;). The bass resonance of cars passing by makes this recording a bit heavy in some places, and the wind made it's mark too, but that shoudn't be a big of an issue here. As i listen to it now, so much things happened while i was asleep. . . [ 3:30 a. M. !: some people are singing and speaking, and you can clearly hear one of them saying: "kurwa, grubo", which means - "f**k, heavy". Later on, the neighbours weren't sloppy too;). Hearing such recordings doesn't give you the liminous feeling of the place where it was recorded. You only get audio here, not the vision, the light, the brightness, the movement, the actions, and the space, the physical elements, only the best can imagine (so if you don't have such an imagination, pm me and i can send you a photo of the place where all this took place). Anyway, i hope that the birds will keep rockin' their solos, and the bees will keep visiting all the flowers around forever! (who knows, i might become one of them sometime;). Thanks and have a good listening session. Szymon.

The same as my other fire whoosh sound, but i used a hi-pass eq at the 50hz mark to take out some of the "mud. ". --. This is a quick fire sound i made using qubodup's "swing 25" public domain/cc0 upload on this site. It's a bamboo stick swinging, which i layered and toyed with to get the results here. For those curious, here are the steps. * i took the file into reaper, and slowed the file's playback rate to 31% of the original. * i then duplicated the file three times, for a total of 4 tracks. * track 1 (lowish gas-burner sound):- reverb (drum-room impulse response, a medium-sounding reverb with a slight deadness to it. In free impulse loader reverberate le, stretched impulse to 150% and set attack time to 0. 218s). - eq (-8db bandpass near 200hz, rising back to 0 by the 1k mark. Low-pass applied at 5. 8khz). * track 2 (lowest of sounds, like a bassy gas-burner):- chorus effect. That's it. (specifically acon digital multiply, a free plugin, set to the "romantic" preset). * track 3 (not as low as track 2, but closer to track 2 than 1)- reverb (a large hall impulse response. No adjustments, ie. No increased attack or stretching like for track 1. ). -chorus doubler (free plugin duet, preset: "basic doubler. " same effect as if i had doubled the track and pitched one up 6 cents. ). - chorus (free plugin acon digital multiply, preset: "romantic. "). * track 4 (most flame-thrower, whooshy of tracks. )- reverb (impulse response says "hall medium," but it's a thick, even echo from start to finish. Makes the sound go from its default "whoosh" to a flamethrower noise. - chorus doubler (duet again, preset: basic doubler). - chorus (acon digital multiply, preset: "romantic. "). Master bus:. - compressor (tdr kotelnikov mastering compressor, the free successor to the tdr feedback compressor ii. Preset: punchy. Thresh: -20. 9, soft knee: -1. 5, ratio: 2:0:1, attack: 7. 0 ms, release peak: 165 ms, release rms: 165 ms, makeup: 1. 5 db, output: 2. 0 db. That's it.

This sound was created using audacity. First of all i chose a frequency of 432 hz ( a number which includes the golden rule/proportion), then i created a gradual rise in the first 4 seconds, leading into a peak which descends so it can go up again, creating an effect of confusion. At the end, the sound raises gradually and rapidly to reach its peak once again. This sound recreates, for me, a fast- moving ufo (unidentified flying object) and includes the notion of conspiracy in our society- the changing of the frequency of the tone “la “ from 432 hz to 440 hz in 1953 by the nazis. La règle d’or- 432 hertz. Le ton « la » est une pointe centrale dans le réglage des instruments musicaux. Le ministre de la propagande en allemagne pendant l’époque des nazis a fait un décret général avec lequel il a changé la tonalité « la »de 432 hz en 440 hz. On utilise cette hauteur à partir de 1939 jusqu’à nos jours. Il y a eu des protestes de la part de professeur dussault de la conservatoire parisienne qui a fait une pétition signé par 23 000 artistes françaises mais sans aucun résultat. L’organisation internationale de standardisation(iso) a accepté en 1953 les changements et on utilise la valeur de 440 hz depuis. Des recherches montrent que ce changement a des effets incontournables sur le corps et le cerveau humain- les gens entrent dans un chaos. Ce changement a été caché du monde entier parce que c’est le point de la balance dans la nature. 432 hz est la vibration qui inclue aussi le règle d’or (ou la proportion de dieu). Quand on écoute de la musique en 440 hz la première chose qu’on remarque c’est une fatigue, aucun envie de faire n’importe quoi et beaucoup d’autres ( y inclus le mouvement de notre adn) une étude récent montre que l’utilisation de 440 hz crée des mouvais effets dans la nature et dans toutes les êtres vivantes. Cette article m’a inspirée à recréer un son avec une fréquence de 432 hz qui monte et baisse graduellement. C’est un son seul de type complexe(nodal). Il est de type v( continu varié), il est éclatant,clair et lisse. L’attaque du début est graduelle et violente. Le son varie en « hauteur » de plus fort au moins fort et l’inverse, recréant un effet d’un ovni qui passe à côté de vous.

A few cycles of my dad's home oxygen machine with a ticking battery operated clock in the background recorded in the early morning in the living room with lifecam hd3000 webcam at the end of about 16 feet of usb cable dragged out of my bedroom. He's about 6 feet away, i was with my back to the room with my camera pointed at my chest so he wouldn't think i was filming. It would seem this is the first and only oxygen machine on freesound. A full cycle seems to last from between 7 to 10 seconds. From wikipediaoxygen concentrators typically use pressure swing adsorption technology and are used very widely for oxygen provision in healthcare applications, especially where liquid or pressurised oxygen is too dangerous or inconvenient, such as in homes or in portable clinics. Oxygen concentrators are also used to provide an economical source of oxygen in industrial processes, where they are also known as oxygen gas generators or oxygen generation plants. Oxygen concentrators utilize a molecular sieve to adsorb gasses and operate on the principle of rapid pressure swing adsorption of atmospheric nitrogen onto zeolite minerals and then venting the nitrogen. This type of adsorption system is therefore functionally a nitrogen scrubber leaving the other atmospheric gasses to pass through. This leaves oxygen as the primary gas remaining. Psa technology is a reliable and economical technique for small to mid-scale oxygen generation, with cryogenic separation more suitable at higher volumes and external delivery generally more suitable for small volumes. [1]at high pressure, the porous zeolite adsorbs large quantities of nitrogen, due to its large surface area and chemical character. After the oxygen and other free components are collected the pressure drops which allows nitrogen to desorb. An oxygen concentrator has an air compressor, two cylinders filled with zeolite pellets, a pressure equalizing reservoir, and some valves and tubes. In the first half-cycle the first cylinder receives air from the compressor, which lasts about 3 seconds. During that time the pressure in the first cylinder rises from atmospheric to about 1. 5 times normal atmospheric pressure (typically 20 psi/138 kpa gauge, or 1. 36 atmospheres absolute) and the zeolite becomes saturated with nitrogen. As the first cylinder reaches near pure oxygen (there are small amounts of argon, co2, water vapour, radon and other minor atmospheric components) in the first half-cycle, a valve opens and the oxygen enriched gas flows to the pressure equalizing reservoir, which connects to the patient's oxygen hose. At the end of the first half of the cycle, there is another valve position change so that the air from the compressor is directed to the 2nd cylinder. Pressure in the first cylinder drops as the enriched oxygen moves into the reservoir, allowing the nitrogen to be desorbed back into gas. Part way through the second half of the cycle there is another valve position change to vent the gas in the first cylinder back into the ambient atmosphere, keeping the concentration of oxygen in the pressure equalizing reservoir from falling below about 90%. The pressure in the hose delivering oxygen from the equalizing reservoir is kept steady by a pressure reducing valve. Older units cycled with a period of about 20 seconds, and supplied up to 5 litres per minute of 90+% oxygen. Since about 1999, units capable of supplying up to 10 lpm have been available.

Recorded in my dad's bedroom with lifecam hd3000 webcam. This is a much better recording than my previous oxygen concentrator file, as i hauled my desktop into the bedroom at the other end of the apartment where the machine now is, when i was home alone. The webcam is on the bed about 3 or 4 feet from the machineat the beginning of the file you hear me flip the big switch and the machine comes on with a long on beep and thumps. I edited it to start then. At 00:1. 8 what i suspect is the water pump comes on, though i may be wrong. That's when the gurgling starts though. The machine has a small reservoir for distilled water to moisten the airflow. A cup or two lasts several daysyou'll hear various hisses and thumps in a 15. 6 second cycle as it runs. At 03:03 i flip the big switch to shut the machine off, and it bubbles and gurgles away for the rest of the file, as water i assume slowly perculates back into the reservoir, the bubbling getting quieter and quieter until it doesn't even sound like bubbling anymore, until it finally ticks to a stop. At 03:16 you hear me step as i get my foot loose from the mic cord lol. At 04:13 the furnace shuts down as a car finishes going by outside in the bass register, faint traffic noises and the furnace being the only background noises you'll hear aside from my moving around a couple times, and a faint bluejay at the end. At about 07:00 you can barely hear the machine anymore, but i could hear a faint ticking with my own ears. At 07:04 the furnace comes back on. At 07:08 you'll hear a bluejay faintly calling outside and a car going by outside after, which finishes the file at 07:20. I edited out my walking to the computer to shut the recording down. From wikipediaoxygen concentrators typically use pressure swing adsorption technology and are used very widely for oxygen provision in healthcare applications, especially where liquid or pressurised oxygen is too dangerous or inconvenient, such as in homes or in portable clinics. Oxygen concentrators are also used to provide an economical source of oxygen in industrial processes, where they are also known as oxygen gas generators or oxygen generation plants. Oxygen concentrators utilize a molecular sieve to adsorb gasses and operate on the principle of rapid pressure swing adsorption of atmospheric nitrogen onto zeolite minerals and then venting the nitrogen. This type of adsorption system is therefore functionally a nitrogen scrubber leaving the other atmospheric gasses to pass through. This leaves oxygen as the primary gas remaining. Psa technology is a reliable and economical technique for small to mid-scale oxygen generation, with cryogenic separation more suitable at higher volumes and external delivery generally more suitable for small volumes. [1]at high pressure, the porous zeolite adsorbs large quantities of nitrogen, due to its large surface area and chemical character. After the oxygen and other free components are collected the pressure drops which allows nitrogen to desorb. An oxygen concentrator has an air compressor, two cylinders filled with zeolite pellets, a pressure equalizing reservoir, and some valves and tubes. In the first half-cycle the first cylinder receives air from the compressor, which lasts about 3 seconds. During that time the pressure in the first cylinder rises from atmospheric to about 1. 5 times normal atmospheric pressure (typically 20 psi/138 kpa gauge, or 1. 36 atmospheres absolute) and the zeolite becomes saturated with nitrogen. As the first cylinder reaches near pure oxygen (there are small amounts of argon, co2, water vapour, radon and other minor atmospheric components) in the first half-cycle, a valve opens and the oxygen enriched gas flows to the pressure equalizing reservoir, which connects to the patient's oxygen hose. At the end of the first half of the cycle, there is another valve position change so that the air from the compressor is directed to the 2nd cylinder. Pressure in the first cylinder drops as the enriched oxygen moves into the reservoir, allowing the nitrogen to be desorbed back into gas. Part way through the second half of the cycle there is another valve position change to vent the gas in the first cylinder back into the ambient atmosphere, keeping the concentration of oxygen in the pressure equalizing reservoir from falling below about 90%. The pressure in the hose delivering oxygen from the equalizing reservoir is kept steady by a pressure reducing valve. Older units cycled with a period of about 20 seconds, and supplied up to 5 litres per minute of 90+% oxygen. Since about 1999, units capable of supplying up to 10 lpm have been available.