551 Royalty-Free Audio Tracks for "Surface"

I strapped an h6 to the frame of a rickety fixed-gear bicycle with no shock absorbers on either wheel. I rode this around a shipping container yard near ahmedabad, on a gritty surface made up of interlocking concrete tiles. Close mic-ed.

Foley movement of puzzle pieces being slid around, picked up and clicked into place on a wood surface. I used a zoom h4n and applied some noise reduction to get the room tone out. Very specific sound, hopefully gets some more use out of it.

Microfone- shotgun shure vp89placa de áudio - behringer u-phoria umc404 hdbarulho seco de batida em metal; barulho de uma pessoa pulando em uma superfície de metal. Microphone- shotgun shure vp89audio board- behringer u-phoria umc404 hddry metal sound; noise of a person jumping on a metal surface.

Intended for game creation: sounds of bigger and smaller spaceships and other noises very common in airless space. How i made them:. Rubbing different things on different surfaces in front of 2 x akg c1000s, then processing them with the free kjearhus plugins and some guitaramp simulators.

Captain, we've had reports of a strong signal emanating from the surface of klumpok b. Time to investigate. Pulsating drone from various synth samples from my analog collection. Small amount of reverb and edited/multitracked looped in roxio sound editor.

This a spare recording from a short film i was making. It's a stereos track but all sounds are recorded to the left channel. This was recorded on a zoom h4n and a sennheiser me67. This sound is me walking on several surfaces near a stream in cornwall, uk. I walk in a woodland first, then on a road, then by a stream.

Man taking a piss in a parking lot. The sound of the urine hitting a hard surface, pavement, in a suburban aural context with zipper at end. Recorded with zoom h2; field recording background has insect chirps and distant highway noise.

**pleace, be carefull and reduce volume. **. This is original sound of a razorblade scratching the surface of glas. This noise was created to make a painfull noise. Headphones recommended. Recorded with zoom h2n - slightly filtered and cut of useless frequencys below 2k.

A close up recording of an overheating usb slot-loading cd/dvd drive that repeatedly tries to spin up, but fails and makes some clicking noises. Note on low frequency sounds: i recorded this with a zoom h1n recorder at about 2cm distance from the drive slot. I held the recorder in my hand and rested my hand on the surface the cd drive was resting on, so there is somewhat of a mechanical connection between the drive's vibrations and the recorder. I believe this led to the low frequency parts of the recording. About halfway through the recording, i lifted the drive up with my other hand and held it at a 30degree angle to the surface and recorder. As you can hear in the recording, this made it spin up a little longer before failing and spinning back down.

I´ve found a more than 2 meters high and wide bronze artwork hanging upright. It has several blocks on its surface, looking just like a upright hanging town. On 5 of the "houses" i played a rhythm, using rather hard drumsticks für kettledrums. Recorded with zoom h4n with 2 schoeps ccm4 mics.

Concrete foley performed with hands. Part of my ‘various hits’ pack - foley on concrete, metal pipes, and plastic surfaced objects in a 10 story stairwell. Recorded on iphone. Added fades, eq’s and compression for easy integration.

This was recorded in a university building in melbourne in 2018. It was after hours, in the evening, so the building was mostly empty. I was in a hallway that had lots of hard surfaces including linoleum floors. I could hear a baby crying in a room that was several metres away. This recording is mostly reverb and its very atmospheric. I just recorded it with my smartphone, but it was such a great sound that i had to get it!.

Recorded at a storm sewer grating at shaw st & manchester ave in toronto's seaton village neighbourhood, on 24 apr 2012. The surface drainage in this section of the city was once carried by the lost garrison creek, and so this might be the sound of the lost creek's waters. H4n sound recorder with sennheiser mke400 stereo microphone. .

I started recording a vinyl lp into my computer before realising that i hadn’t set the anti-skate properly and the needle was stuck in the lead-in groove. I trimmed this bit of snap crackle n’ pop and kept it in the hope that it might be useful for me or anyone else. Have fun.

This is a first attempt to record sound underwater, i build a small hydrophone according to the instruction gave us by digifishmusic, i could probably make it better but all considered i'm pleased whit it. The hydrophone was placed in a small river near where i live, just below the water surface but unfortunately it kept bouncing against the rocks so it's a bit noisy. Enjoy!.

This is a reverse ricochet accent i made from scratch. I took the classic “h-b cartoon ricco” and modified it to make it look like an approaching bullet is coming to shoot a glass object or hit a hard surface. You can use this sound however you want. Just give me credit!.

Hey everyone,. I love freesound so i thought i'd contribute my first sample. I found that people love dropping coins on every surface imagineable except for grass. Recorded on a zoom h4n for use in this dota 2 short film - https://www. Youtube. Com/watch?v=wdv1mia1_1k.

I hadn’t had sex for so long but this guy was so hot i let him fuck me on every surface in my apartment. Had trouble getting him inside my tight ass at first but then he bred me bareback.

This mp3 contains a series of sounds that can be divided into individual elements if needed. I set down a full, unopened can of beer several times on a hard surface. Then i opened the can of beer. Then i placed it down again and flexed the aluminum a bit. Finally, i took a long gulp of beer and let out a satisfied "ahhhhhh!" now i'm drinking the beer as i upload this file. Mmmmmm. . . Beer.

Lead in groove of a 7" single @ 45 rpm. Recording chain:. Pro-ject primary turntable with an ortofon om 5e cartridge→ onkyo stereo amplifier→ behringer uca202 audio interface→ laptop using audacity. Notched out some motor noise and selectively eliminated or lessened some other noises for aesthetic reasons.

Stopped in a tiny museum in kansas and the curator turned on the 1900s edison photograph for me and let me record the classic sound of music with all the hums and associated scratches. The music sounds like an old turn of the century carnival to me. Recorded on my cellphone and cleaned up in audacity. Production-now. Com - shout-outs welcome.

Perfect walking sound effect. Sound of several people walking buy on a hard surface with hard shoes. You can hear the sound reverberating off the walls and solid flooring.

I really needed something that sounded like a group of horses galloping in the distance and couldn't find anything. So i busted out my zoom h6 and set it on my futon comforter and then just tapped my fingertips on the surface right next to the stereo mics. Then i put that track in premiere and made four layers, all offset to get different rhythm and i thought it turned out pretty good so wanted to share it.

Https://www. Youtube. Com/channel/ucneirnarxcfnpvwzlwg2pzg. 빗자루로 눈 쓰는 소리를 만들어봤습니다. ----------------------------------------------------------------------------------you can use the sound freely ( i made it )if you interest my sounds, please visiting my youtube channel!!!--------------------------------------------------------------------------------. 누구나 쓸수 있는 무료음원입니다. 사운드가 도움이 되셨다면,저희 유투브 채널 한번 방문 와주시면 감사하겠습니다 ^^. 무료효과음, 무료bgm 꾸준히 업로드 하고 있으니 제 채널 한번 보고 가세요!!감사합니다.

Cell phone vibrating on a hard surface, recorded from within. I put a nokia 6060 on top of a turned-over plastic ikea bin and a zoom h2 under it. This sound is cc0 but i highly recommend that you include a link to this page when using it, to avoid misunderstandings. Http://farm9. Staticflickr. Com/8070/8213683889_517a10ef52_o. Pngon flac and ogg vorbis audio file formats. Contact me if you have interest in specific sounds for open source or commercial purpose.

A drain after a water flow: the water seems to build up a physical-mechanic surface tension kept mass in the tube, opens and closes this bubble-entity producing a specific rhythm in the plughole resp. The drainage pipe. It pulses with various plops and splashs, starts off with a firework kind of beat but then one hears a differentiated rhythm of 4-strokes sequences with slugs before these etc. Getting slower. Many minutes later it ends (beyond this track). The (hearable) cut is just the censorship of a small abortive piece -- left in to document the recording as recording.

This song is about a buddhist who returns to the monastery, where he was abbot centuries before (in a previous life). While walking along the path with torches, the memories come to the surface. First, it is difficult to see it without understanding it. After a while he can let it come to him, without exercising control. As a result, he learns the life lessons that he was not yet ready for. Through the light at the end of the path he experiences what enlightenment is:"dare to expose everything without judgment and learn from it to become more loving instead of always needing control".

Cell phone vibrating on a hard surface, recorded from within. I put a nokia 6060 on top of a turned-over plastic ikea bin and a zoom h2 under it. This sound is cc0 but i highly recommend that you include a link to this page when using it, to avoid misunderstandings. Http://farm9. Staticflickr. Com/8070/8213683889_517a10ef52_o. Pngon flac and ogg vorbis audio file formats. Contact me if you have interest in specific sounds for open source or commercial purpose.

A steady rain falls silently through the still december night air, then splatters all over the tile and cement surfaces of a back yard, splashing in standing water. A hint of space from brick/stucco fencing and house bounding all sides. Akg perception 400 large diaphragm mid-side stereo pair in omni+fig8 mode > sound devices mixpre-6 @ 24/96. See also: musical dsp processed version of above:https://soundcloud. Com/chromakei/watercolor.

Stopped in a tiny museum in kansas and the curator turned on the 1900s edison photograph for me and let me record the classic humming, scratchy sound of a turntable turning. The steady rhythm had a very "bioshock infinite" feel to me, and i loved it. Nice to put under music to make it sound old. Recorded on my cellphone and cleaned up in audacity. Production-now. Com - shout-outs welcome.

Create thằn lằn khổng lộ sound from amhola's’s «crashing-waves-into-rocks-3" sound. I need splash for big animal in ocean but can't find whale splash (maybe see if find us navy have submarine video with should of submarine fly and splash on ocean surface). Audacity:. • cut 24. 443s to 29. 286s. • file→new. • paste. - effect→change speed. . . Speed multiplier: 0. 450. • select from 7. 790s to 10. 763s- effect→fade out. • select from 0. 000s to 1. 637s- effect→fade in.

Cell phone vibrating on a hard surface, recorded from within. I put a htc wildfire smartphone on top of a turned-over plastic ikea bin and a zoom h2 under it. This sound is cc0 but i highly recommend that you include a link to this page when using it, to avoid misunderstandings. Http://farm9. Staticflickr. Com/8070/8213683889_517a10ef52_o. Pngon flac and ogg vorbis audio file formats. Contact me if you have interest in specific sounds for open source or commercial purpose.

25 footsteps (walk) on different surfaces. You can find : dirty ground (x5) // tile (x5) // barefoot water (x5) // average depth water (x5) // snow (x5). More footsteps sounds : https://freesound. Org/people/nox_sound/packs/29889/. Unity devs, footsteps - essentials sound pack for free in the assets store: https://assetstore. Unity. Com/packages/audio/sound-fx/foley/footsteps-essentials-189879. You can edit it with reaper/audacity/etc. Gear : rode ntg4+ // tascam dr-05file: 48khz, 24 bit, mono, wav.

Two contact microphones recording an engine from a mini cooper s in sport mode. Surprisingly aggressive-sounding. Intended to use for a race car asset. Contact microphones are stethoscope-like mics that you place onto a surface to record vibrations. This way, i was able to record the raw engine without wind or perspective. The left channel is the chassis and the right is the engine block. . . Blending the two together produces a great sound. Free to use.

I wanted to find a good creative commons 0 sound effect of fingernails scratching on a wooden surface but i could find the exact thing i was looking for. So i recorded myself scratching my bedroom door with my fingernails using a recording app on my phone and edited it in audacity to remove breathing sounds, and to make the sound feel more heavy/deep, including some very faint reverb. Since i really wanted this i thought it might be useful for someone else! i hope someone else out there like me finds this somewhat useful. Theres a bit of a clicking noise at the end - i think from the recording process.

I'm currently working on some musical ideas for a good friend's cartoon series and thought i'd upload this little experiment with an old vinyl of some mozart. I recorded the output of my deck and messed with the speed and pitch, as well reversing the audio and adding some distortion and other effects once it was in my daw. Sounds pretty creepy! if this proves popular i will upload some more of my "musical" experiments! enjoy!. My soundcloud: https://soundcloud. Com/mattcmusic.

The sound of the bottom of a ceramic mug, dragged over the metal grating of a coffee machine. It sounds like a sword drawn from a scabbard. Recorded using a zoom h6 in the kitchen. Applied a filter to remove unwanted low and very high frequencies. Also corrected the volume level to adjust all four recordings to the exact same level. There are some minor distracting noises - i assume from my shirt while moving the mug over the surface. Also a fan is very faintly audible in the background. If you are interested in a very clean recording of this sound, please let me know.

Around 2010, i circuit-bent a motorola cellphone and added a control surface to control the bends. Then i added an atari paddlewheel so its big potentiometer could be used to do pitchbends, and the result is an instrument i called the "sonic electronic ball breaker". It's got knives, quarterstaves, thor's lightning, sharp sticks, nuclear machineshotguns, and even some claws that come out to jab 'em. In this sample i'm going through and playing with the controls to see what i get. These sounds are pretty abrasive, but they work well when run through a bunch of effects.

Stereo recording of the lp "dance hall of shame"a silent record released by virgin records protesting censorship in music. From the sleeve:"if there is one lesson to be learned through our history, it's that freedom of speech has inevitable risks. But the alternative is slavery of mind, in a society empty of thought. If we value the progress of music and expression, we must accept that there will be music we dislike and lyrics that offend. Our responsibility lies in promoting legitimate argument and persuasion. If we do more than this, overstep our bounds with labeling and censorship, then our unwillingness to accept the risk of freedom leaves only one future to our children: no thinking. No talking. No music. ".

I noticed there were no dry ice on oven rack sounds here so here is a recording of dry ice interacting with a steel oven rack. As the dry ice melts it creates vibrations on the metal that evolve as the material travels across the surface. It is an awful sound resembling a combination of saxophone, violin, bagpipe and screaming (any species). This was recorded on halloween 2018. It was a tradition in my family when i was a kid to get some dry ice on halloween and fill beakers with colored water to surround the candy display. The addition of dry ice on oven rack sound effects developed later and truly scared a lot of kids because it is so loud and terrible. These days we make some dry ice kief as well which makes the holiday even more festive and weird.

(recorder: zoomh4npro 2018)(microphones: zoomh4npro 2018 on-board microphones). This is a recording of illegal fireworks being launched all over los angeles on the 4th of july, 2020. All surface to air fireworks are illegal but, due to covid-19 cabin fever, people just didn't care this year. This recording is almost 99% voice free. There was a couple on a balcony that are barely heard muttering something in just a minute or two of this recording. For the most part, it's clean. I kept the peaks very low to maintain a natural sound. All of my sounds recordings are provided free of all charges. I give all rights to the down-loader for any purpose either personal or commercial. Enjoy!. Christopher c. Courter.

It's a recording of a calcium-sandoz® forte/fuerte 500 mg effervescent tabled falling into a glass of water and dissolving. You can hear the tablet dropping into the water and water droplet hitting water surface back. After w while - co2 buubles start to appear creating noisy sound. The recording has a long natural fadeout and unfortunately some background noise. I leaved "silence" before the sound starts so you can de-noise the recording to your needs (i prefer audacity for denoisig). Recorded inside of my wardrobe for acoustic isolation using zoom h2 on a mic-stand. Recoded as 96khz/24-bit wav. Normalized, truncated and convertet do 16-bit flac using audacity. I've converted this to 16-bit as it still has plenty of noise and 24-bits would not be any better after normalization.

Sharpening knife : sharp sound. The sound was post-processed to make the sound of the knife seem more scary. Afiando faca : som afiado. O som foi pós-processado para fazer o som da faca parecer mais assustador. Dragging a knife : shaky sound of a knife being dragged on an irregular surface. Arrastando uma faca: som trêmulo de uma faca sendo arrastada em uma superfície irregular. Girl yelling : high pitched sound. The sound was post-processed to seem like the sound happened in a room full of echo. Garota gritando : som agudo. O som foi pós-processado para parecer que o som aconteceu em uma sala cheia de eco. Gravados com um microfone shotgun shure vp89 e uma placa de som behringer u-phoria umc404 hd. Gravado no estúdio da escola ort no rio de janeiro, em fevereiro de 2022.

Several years back my older brother stumbled upon a bunch of old family reel to reel films and sat down one evening to project them on a wall and digitize them. This is the sound of that process. What you can hear, i imagine, is the noise of the projector in the left channel and the sound of the reels in the right channel. I've been obsessed with the sounds of the infinite variation in old analog hardware. As a sound designer, that infinite variation is often sought after but rarely, or accurately, reproduced through digital files in various libraries. Of if they are, they're often too short to cover whatever scene i am trying to fill. On the surface it's just noise but if you listen closer it's this wonderful cacophony of overlapping and repeating sounds that are always looping but never quite identical on each rotation. It was ripped from youtube using audio hijack at 48khz/16bit, but due to youtube re-encoding things as youtube does, it's nowhere near the source. It's still, in my opinion, a sound worth sharing. Enjoy!.

Zoom h4n - onboard microphones. This recording was captured in the city of orange in orange county, california. This is located just below los angeles and less than a mile from disneyland in anaheim. This is an extremely clean recording of a sudden cloudburst that turned in to a torrential downpour on december 28, 2020. The peaks are all very close to 0db. I opened the sliding glass door to our balcony and placed my zoom h4n as close as possible to the rain without destroying the recorder. What resulted is an amazingly layered rain track. This is because rain can be heard striking multiple surfaces such as a tree, a metal table, the cement balcony, etc. . . There is not much thunder (that's rare in this area) but if you need a few dramatic thunder claps they can be found at the following times one the file is downloaded. Note: that the rain decreases in intensity near the end. 8:09 - 9:37 - 10:31 - 11:20. - christopher.

Pistol fired outdoors with ricochet. Single shot, fairly close, with fast fadeout. Narrow stereo image, no panning, almost monophonic. Wholly synthesized. No weapon was fired in the making of this sound. It's an emulated sound effect of a sidearm gunshot with a cliche ricochet sound, like in the vintage western movies and ww2 films that they showed on tv when i was a kid. Can be used in a game, perhaps, or a none-too-serious vidclip. The sound of the pistol cartridge explosion is default flstudio kick, clap and snare slowed right down. A single tap of delay is added to lend an impression of echo off a middle distance hard surface. The ricochet noise was made with sytrus running as a vsti inside flstudio. It took an entire day of head scratching, oscillator tweaking and envelope mangling to get something that reasonably resembles a sound that i recall from the old movies. I think i'll shoot myself before i try something like this again. :). Plus the usual flstudio compressors, eq, reverb and delay - nothing tricky, just standard stuff.

Mud volcano field, davis-schrimpf seep field, salton sea, california. Lat: 33. 20070326716746lon: 244. 42179501054162. The davis-schrimpf onshore seep field site in the salton sea geothermal system is the result of shallow magmatic intrusions in a sedimentary basin. The ssgs is situated in the salton trough in southern california, an area with abundant surface manifestations of hydrothermal activity. The hydrothermal system in the salton trough occurs in a pull-apart setting where rifting and associated magmatic intrusions are responsible for the strong heat flow. One of the most concentrated and well-expressed onshore seep fields is the davis-schrimpf field, where more than 50 individual seeps are located in this area. Gas venting from gryphons and pools is vigorous with a continuous bubbling activity. Water and mud mixtures are continuously expelled down the flanks of the gryphons. Carbon dioxide produced from de-volatilization reactions involving sedimentary carbonate is the main driver for the seep activity. The morphological features of the davis- schrimpf seep field are strikingly similar to seep fields on dormant mud volcanoes however, the davis-schrimpf seeps are not related to mud volcanism, as mud volcanism normally implies large-scale mud breccia eruptions and a low temperature seep stage. From the; journal of geophysical research, vol. 114, b09201, doi:10. 1029/2008jb006247, 2009.

Individual gryphons, davis-schrimpf seep field, salton sea, california. Lat: 33. 20070326716746lon: 244. 42179501054162. The davis-schrimpf onshore seep field site in the salton sea geothermal system is the result of shallow magmatic intrusions in a sedimentary basin. The ssgs is situated in the salton trough in southern california, an area with abundant surface manifestations of hydrothermal activity. The hydrothermal system in the salton trough occurs in a pull-apart setting where rifting and associated magmatic intrusions are responsible for the strong heat flow. One of the most concentrated and well-expressed onshore seep fields is the davis-schrimpf field, where more than 50 individual seeps are located in this area. Gas venting from gryphons and pools is vigorous with a continuous bubbling activity. Water and mud mixtures are continuously expelled down the flanks of the gryphons. Carbon dioxide produced from de-volatilization reactions involving sedimentary carbonate is the main driver for the seep activity. The morphological features of the davis- schrimpf seep field are strikingly similar to seep fields on dormant mud volcanoes however, the davis-schrimpf seeps are not related to mud volcanism, as mud volcanism normally implies large-scale mud breccia eruptions and a low temperature seep stage. From the; journal of geophysical research, vol. 114, b09201, doi:10. 1029/2008jb006247, 2009.

This is a collection of "small room reverb" impulse responses that i sampled in a new england home known as butternut lodge, built and owned by actress bette davis back in 1940. It consists of all wooden rooms with many non-parallel surfaces, rugs and furniture and includes 3 round-shaped "silo" rooms! these rooms sound clean and do not have the irritating "ping" of many rectangular rooms. Short history/pictures of butternut (https://www. Airbnb. Com/rooms/24692769?source_impression_id=p3_1659215694_liuasyfxoceab5fn). Although these round shapes (and some of the other very small rooms) could potentially wreak havoc with phase at specific frequencies when summed to mono, i recorded this using the mid/side mic technique; therefore, the "side" channels fully cancel out, leaving a clean monaural reverb signal. These irs are stored as flac files. They can be used directly by any daw without conversion and have the added feature of being id3 tagged with a photo of the room each ir is taken from. After downloading, select view -> large icons in the folder to view the rooms. I sampled each room using a swept sine wave into a jbl flip 6 bluetooth speaker; recorded through a tascam tm-st1 m/s stereo microphone, feeding a tascam dr-07 recorder @ 24-bits 44. 1 khz and deconvolved using reaper. As of this post, i've been using these rooms for about 2 weeks. So far, i've found the "garage" to sound fantastic on drums! the drum sound! also, many of the other smaller rooms have a great effect on guitars, keys, and hand percussion. Each room varies in tone and brightness, so i've found that selecting/tuning the reverb send works well if approached like an eq. Increase the effect send until the instrument "feels" right (then perhaps back off slightly). A close-miked acoustic guitar, for instance, will take on a nice brightness and 3-d quality; not particularly reverberant, just big. At that point, i recommend applying any eq, compression, and bigger-sounding reverb effects. Hopefully you enjoy this. Please let me know how you like it and if you have any suggestions. Cheers!. Ken.

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.