Silent CD (& MP3s)

What is this?

A CD of silence. (Strictly not a CD of silence, of course, but audio files of silence which one can burn to a CD-R to make a CD of silence.)

The tracks are of 2, 4, 8, 16 & 32 seconds and 1, 2, 4, 8, 16 & 32 minutes duration so they can be combined using the play list feature of a normal compact disk player to give any duration (in even numbers of seconds) from 2 s to an hour (well, up to 1 h 4 min 2 s, to be pedantic).

Uses

  1. Novelty item: This is the main reason I made it. Surreal, silly or stupid depending on your sense of humour.
  2. Inserting blanks: Sometimes one wants gaps between tracks (for example so that one can run between a CD player & a dance floor when one is both dance teacher & DJ, as I have been at times, using an audio system without a remote control) and to have a track break marker between the gap and music track (so that one can skip the blank if needed). To do that, just insert one of these silent tracks between each music track before recording. I've had reports of these silent tracks being used for styles as varied as folk dancing, clubbing, zumba & yoga.
  3. Shutting up an irritating jukebox: If one wants peace & quiet but someone else keeps playing CDs on a jukebox or a CD player to which you have access, replace their CD with this one. It can similarly be used to shut up some irritating mobile telephones by converting a silent track to an MP3 and installing it as the ringtone.
  4. CD player noise test: It can be used to test a CD player, amplifier & speakers for background noise. As there is no sound on the recording, any noise one hears from the system when playing this is noise added by the playing equipment.
  5. Practical joke: I had not intended it as a practical joke but found that one of my friends to whom I gave a silent CD tried playing it in a PC and assumed that the computer was failing when it gave no sound out (despite the CD being clearly labelled 'Silences'). He was going to waste time in a futile attempt to debug his music playing software.
  6. To silence a CD player when using it as an amplifier (e.g. converting a car CD player to aux-in): If one needs to use a CD player as a amplifier for an auxiliary input, such as from an MP3 player, but the amplifier only works with a CD playing then this can be used as a dummy CD to keep the CD player happy without producing unwanted sounds. (This use was invented by a reader of this site, Kane Zhu, who used it to fit an MP3 player to a car stereo system in addition to a CD player when the stereo's only external input was a dedicated CD player one. Years later another reader told me that my silent CDs had become widely used when modding car CD players to add aux-in.)
  7. To silence a smart phone when using it to output sound from apps: Several years later another reader similarly found that an iPhone would only push sound from a satnav application to a car hands-free speaker system when it was playing music and hence used a silent track as the music.
  8. To silence noise cancelling headphones: Another reader told me that he had got noise cancelling headphones for quietness, not music, but found that they needed to be Bluetooth paired to an audio signal source to operate. Hence he likewise used a silent track from here.
  9. To see music player program animations uninfluenced by music: Some music playing computer programs display decorative animations that adapt to the music. To see what they look like when active but free-running without music to control them, play a silent track. Some can look very different to their normal appearance and may even be more aesthetically pleasing.
  10. To skip music player first track: A reader of this site reported a music player with a bug in its random shuffle - it only shuffled after it started playing so the first track was always the same. The solution was to put a short silent track at the start of the playlist to sacrificially take up that unwanted slot virtually unnoticeably. (The reader left no return address so I can't credit them here.)
  11. As a random timer: The same reader used a random playlist of silent tracks plus an alarm track as a substitute for a lost random timer of a board game.
  12. For timing theatre sound effects: A reader told me of using them in a theatre both to time sound effects.
  13. For timing: That reader also used them theatrically to prevent accidental running into the next manually timed sound effect on forgetting to press pause. It was particularly of use lest the sound effects system was accidentally left on during the interval.
  14. To keep track numbering through episode gaps: A reader wanted sequential numbering of a series of tracks but the series had gaps (combined episodes in their case). Filling the gaps with empty tracks caused some old iPods go wrong & overheat (!) but silent tracks worked.
  15. To stop a Bluetooth speaker from going to sleep: Some speakers have time-outs which save power by turning the speaker off after a period with no audio playing over Bluetooth. This can be annoying (the reader who reported it was planning a wedding service which, of course, has talking sections). Playing silence over the Bluetooth link can keep some speakers from timing out.
  16. To avoid the start of voicemail messages being lost: A reader reported that in sending automated announcements to some voicemail systems, particularly on mobile phones, latency can cause the first second or so to be missed. Prefixing the announcement track with a 2 s silent track works around that.
  17. To remove a PC sound driver start-up delay: A reader reported that a Realtek audio driver on MS Windows had a 1s delay on alert beeps, such as when Caps lock was pressed. This was because the driver kept unloading. Playing a long silent track in the background fixed it by keeping the driver loaded.

Thanks to all the readers who have sent me new uses they found for the silent tracks! Only the first 5 were originally from me.

CD Limitations

If you burn the tracks to a audio CD formatted to play in a normal old audio CD player then there are 2 restrictions imposed by the original CD spec:

  1. All tracks must be >=2 s long. Therefore the 1 s second track must be omitted. (I've included it in the download for completeness anyway though.)
  2. Although one need not have gaps between the tracks on a CD, it does require a 2 s gap before the first track. This will add about 2 s to the total timing of silence when playing in a conventional CD player (but the spin-up time adds to that as well).

Additionally I have come across (just) one CD player that mistakenly reported that the whole CD was of zero length. Maybe it tried to automatically skip the silences!

CD Burning Advice

If using the ready-made image rather than individual WAVs, then only the CD-R not CD-RW is relevant as I have already done the rest in making the image.

Compressing Nothing

Silence losslessly compresses very well. However the common file compression algorithms are not designed for pathological cases like this (six hundred million identical zero bytes!) so it needed two passes. The original 646 MiB of WAV files compressed a thousand-fold to a 640 kiB .tar.gz file. Compressing this again reduced it to a minuscule (by CD standards) 3.55 kiB .tar.gz.gz file. This is an astounding 186 000 to 1 compression ratio overall.

Indeed it compresses better by lossless Gzip or PKzip than by lossy MP3. At the lowest quality MP3 encoding that Apple iTunes player offers (16 kibit/s mono), it came to 3.7 MiB, over a thousand times what lossless compression can do. Although those MP3s can then be zip compressed (as the they mainly consist of just duplicate block headers), fully lossless is still smaller. Most audio players however would need lossless audio stored uncompressed & some don't even handle anything but the old de facto standard of MP3, I've included the MP3s here as downloads too.

Even better, the 663 MiB CD image compressed down to 2.36 kiB, a 280 000 to 1 compression ratio.

It is not often that one can download an hour long CD over a 56 kibit/s modem in under half a second!

Warning

In trying to hear sound from this CD, one is likely to turn the volume up high. Remember to turn it back down to a sensible level before later playing a normal CD.

Copyright Issue

I think it is okay for me to give away this silence for free (released under Gnu Public Licence). There has been one notorious case of the estate of J. Cage suing M. Batt for selling a silent recording, Cage having been an avant garde composer who had previously published a famous silent piece. However it was reported that the suing was because Batt had jokingly credited Cage with joint composership of the track without asking permission first & profited from the publicity of that creditation without paying royalties. The suing was not merely because it was silent as the general concept of silences in performances & broadcasts pre-dates both Cage & Batt. Anyway, it was eventually revealed to have been primarily a publicity stunt arranged between the two sides.

Furthermore, both Cage's & Batt's silences were both based on the specific novelty of being 'performed' on classical musical instruments whereas the silences downloadable here are purely computer generated (in Syntrillium Cool Edit) loads of zeros.

My actual inspiration for a joke silent recording came from David Nobb's 'The Return of Reginald Perrin' in 1977. In that humorous story, a fictional company included in its deliberately useless product range silent vinyl records with titles such as 'Trappist Monastery Chants' & 'Laryngitis from Many Lands'. It was twenty six years before I got around to making one!

Download

Download silent tracks:

By Andrew Hardwick.
Distributable under GPL or CC-by-sa freeware licences.
Silent tracks made 2003/8/01. Page written 2005/3/6. Updated 2006/1/7, 2008/12/31, 2009/5/30, 2012/4/4, 2013/1/28, 2013/8/18, 2014/10/4, 2018/5/12, 2018/7/13, 2019/9/7, 2020/12/15, 2021/10/6 and 2024/7/19.
Available on-line at http://duramecho.com.