Ask MetaFilter questions tagged with audio and noise

free sonics

philip-random — Wed, 27 May 2009 08:12:25 -0800

What sort of free online resources are there for quality audio samples? I'm looking for a reasonably well cataloged library of random conversations, sound effects, good old fashioned noise etc for application to some sound collage projects I'm working on. I realize that somebody recently asked if there was an audio Youtube out there ... but I'm hoping for something easier to search and of a generally higher audio quality.

How can I make a book that sings?

gwpcasey — Fri, 15 May 2009 06:42:23 -0800

How can I make a book with sounds for a baby? I would like to make a book for a baby that plays a different sound on each page. It would have to be a sound that I can record. I have found very limited resources on the web but suspect it's because I'm not searching effectively.

What would be the best way to do this? Are they existing solutions out there already? Should I just build it myself from the ground up? I want to be able to have 8-12 sounds/clips per book (one per double-page spread) and be able to illustrate and write on the pages as well.

I have a number of different books that I want to make so I won't bore you with the details (animals, music, voices of distant family members etc) but I need to be able to record the sound and/or load it onto something.

I don't mind if we have to push something on the page to make the sound play rather than it playing automatically when we turn the page.

Thanks in advance.

Lite Rock, Less Talk? I'd like neither, please.

strangecargo — Thu, 15 Jan 2009 00:59:16 -0800

(Electronics|Stereo)filter: What is causing this infuriating noise in my preamp and how do I fix it? Links to sound files and long list of symptoms in extended. I have this preamp and ever since moving to my current apartment in San Francisco, it generates a really loud noise that sounds like a combination of 60 Hz hum and FM radio broadcasts. The noise is loudest when the volume knob is turned all the way down, but it doesn't go away when you turn the volume up. And this is what it sounds like when you go from zero gain to full gain and back. The noises don't sound that loud when played back on a computer, but that level of noise is pretty dang loud when sent to the input of a power amp.

The maybe pertinent facts (numbered because there are a lot of them):

1. I recorded the linked sound files by plugging in the output of the preamp into the line in of a MacBook Pro. No mixing or diddling with the file other than that.

2. You can clearly hear the station identifier for KOIT in the first sound file I linked. This is an FM station. What the heck? I was under the impression that FM was way too complicated for equipment to randomly pick up unless it was designed specifically to, you know, receive FM radio.

3. Changing the vacuum tubes inside the preamp doesn't change the nature of the noise.

4. I have other audio equipment (both solid-state and tubed) that doesn't make this sort of noise.

5. The noise is generated independent of what I have connected as an input or output (or if there's anything connected at all).

6. I can't seem to reproduce this noise outside of my apartment (friends' places, hifi shops, etc). Whenever I try, the preamp is noiseless and dead silent.

7. Physically moving the preamp around my apartment doesn't seem to change the noise either.

8. I live in an old apartment without grounding in most of the electrical sockets, but the noise doesn't change if I plug the preamp into a grounded outlet. I've checked that the grounded outlets in my apartment are indeed grounded with one of these devices.

9. I live sort of near Sutro Tower (but who in SF doesn't?). Wikipedia tells me that KOIT broadcasts from Sutro Tower. I also live right next to the N Judah MUNI line. Sometimes my lights dim when it goes by. I suspect the power is probably kind of dirty.

10. Using a different power cable doesn't do anything.

11. For what it's worth, here's a look at the circuitry inside the preamp.

I've been investigating this problem on and off for the last year or so and I still haven't figured out what's causing the problem. Do any electrical engineer types have an suggestions for further testing or solutions to this problem? I have a digital multimeter and oscilloscope at my disposal for the collection of further data.

I'm quite attached to this preamp (more so when it isn't making this noise), so please don't tell me to replace it.

Hmmmmmmmmmmmmmmmmmmmmmmm

vernondalhart — Thu, 07 Aug 2008 09:43:43 -0800

I seem to be getting a regular ground hum-type noise when I record onto my Macbook. I have two older analog synths, both plugged into a mixer, which is then hooked up to the macbook.

Clearly, the noise is coming from the one synth: If it isn't plugged into the mixer, I get no noise; if it is, I get noise. However, if I plug headphones into either the synth or into the mixer, I don't get any noise; I can only hear it when I'm listening to the final result through the macbook.

Why is this? This doesn't seem to make much sense to me.

As an aside, it wouldn't be quite so bothersome if Audacity would be able to remove this noise; it's clearly a very regular ground-hum type noise; but if I get a noise profile from before recording, and use that to eliminate the noise, it doesn't do anything noticeable to the resulting audio.

Any ideas? I've tried using different cables, I've tried pluggin the synth directly into the macbook to no avail. It'd be nice to be able to record from the keyboard, but as it stands, I seem to be out of luck.

How do I stop the noise from my motherboard coming through my speakers?

Grod — Sat, 16 Feb 2008 19:27:33 -0800

I have an old bose acoustic wave radio serving as my PC speakers. Powered but not connected to the computer the speakers produce a gentle hissing. When plugged in (via a 3.5mm to RCA cable) I hear noisy static -- not pure white noise, far more annoying -- and an intermittent whine that changes pitch depending on what's going on in the computer. For example, if the processor is under greater than 30% load all the noises go away. This does not happen with headphones so I think it is some combination of noise in the computer circuits and the amp built into the radio. My question is how do I make it stop? This is my only audio equipment and doubles as my alarm clock. Most of the time I can ignore the sound but sometimes it gets inside my skull and drives me nuts. There are all sorts of odd sounds I can't describe, when there are lots of read/writes to the ram I can tell by the sound. Very irritating. (Sometimes, like now, I end up with ringing in my ears which may or may not be related. Testing that is another reason I want to eliminate these noises.)

That awful noise.

tmcw — Thu, 04 Oct 2007 12:42:51 -0800

How do I tackle feedback with a piezo pickup on a very small instrument (ukulele), running it through guitar amps or PA systems? So I have a concert ukulele, and I've hooked it up with a K&K Big Shot piezo pickup, positioned right behind the bridge. I've been running it through either a Fender Princeton 112+ or Peavey Classic 30 guitar amp, and I've found that any high volume will cause almost unavoidable feedback - even when I'm holding all of the strings still. The problem seems to be reduced when I cut off the mid & bass at the amp level. I know that distance is pretty key here - I need to be further from the amp - but it's still pretty bad. Is there anything that performers do about this that I don't know about? I'd really like to get this thing in action and on stage someday.

Thanks!

Removing video cross-feed from the audio mix

Pronoiac — Sun, 15 Jul 2007 16:58:46 -0800

At a recent lecture, I taped from the soundboard & from some microphones. I meant to record these to separate channels, but I accidentally left it in low quality mode - mono, 22khz. It sounds like video got thrown into the mix. Can I salvage the audio? This three-minute excerpt is all I really need. It's from a backup recording device, & this is the only gap from the main recording.

Want a quick listen? Here's an mp3 (1.4 meg), with frequencies below ~100hz & above ~5khz removed to try to be nicer to speakers.

If you're brave, here's the original, uncompressed, excerpt. (8 meg wav file)

Compressing Dolphin vocalizations and Boat noise?

Racergirl — Mon, 25 Jun 2007 00:37:53 -0800

Hi there, I am doing an honours project on the effects of boat noise on dolphin communication and my supervisor had this idea of using compression to analyse this. He basically suggested that we record dolphin vocalizations in the presence and absence of boat noise, and then compress the files and determine which compresses more (dolphin sounds with the boat noise, or dolphin sounds without the boat noise). His thinking was that less complex sounds should compress less...so he thinks that boat noise will compress less than dolphin vocalizations. Thus, if dolphin vocalizations happen to compress more in the presence of boat noise than they do without the boat noise...this would sort of imply they are "losing information" so to speak. Does this make sense? I asked on another forum, and most people seem to think the opposite - that boat noise will compress less than dolphin sounds because it is more random. This makes sense to me...because i guess boat noise has a lot of different frequencies making it hard to compress. I mentioned this to my supervisor, and he suggested maybe cutting out the random high frequencies in the boat noise to make it more level with the dolphin sounds and then compress from there and compare them.

I was wondering what all your opinions are on this in general? Do you the idea would work?? If not, why? And do have suggestions for something else i could do? I have no experience with audio related things, so this is completely new to me. I am really interested in hearing what you have to say and ANY advice would be greatly appreciated. Thanks!!

P/s: I will be using a lossless compression program like Flac to compress the raw files. I have been out in the field and so far just have a recording of dolphin sounds in the presence of boat noise ...so i still need to get a recording of dolphin sounds *without* the boat noise to test it out.

Which flash-based, non-iPod audio players have the lowest self-noise (lowest noise floor)?

lorimer — Fri, 13 Apr 2007 12:12:50 -0800

Which Flash-based, non-iPod audio players have the lowest levels of self-noise (lowest noise floors)? My mp3 player is good but old, so despite being very well-engineered in other ways it has self-noise that can still be detected over quiet or non-continuous music. Please suggest a replacement with unusually low self-noise if you know what I'm talking about.

I've read that the Archos hard drive-based players have extremely low noise floors (see the last graph on this page), but I'm looking for a light/Flash device.

Numbers like that would be great and subjective reports would also be great (like, "Of all the players I've tried, x is lowest").

(As I said, I'm asking for non-iPod products only. I'm firm on this and the reasons why are not the topic of this thread, so please respect this, thanks!)

Get this Mother^$(ing Thump out of my Mother$(#ing car!

toxic — Tue, 29 Aug 2006 20:49:00 -0800

Very strange electrical noise getting into radio on newly imported 1997 JDM Toyota Tercel hatchback. Radio replacement is imminent, but there's So I bought this car, without checking to see if the radio worked, because I'd planned to replace the radio anyway (Japan's FM spectrum is 70-90 MHz, New Zealand's is the more normal 88-108, so even if it were working, the original Japanese radio would only get 2-3 stations).

A couple of days after I bought the car, I turned on the radio for the first time, and was greeted by very strange noises.

The noise is a repeating "Thump Thump Thump", that comes out of both speakers when the stereo is turned on. It doesn't matter what the volume knob is set to, it doesn't matter where the fader/balance knobs are set, it comes out of both speakers at the same volume (fairly loud, but not eardrum-shattering)

I'm hoping that this is just a bad amplifier in the stock unit, and that the replacement radio that I've got ordered will take care of this, but I'm concerned that it may be indicative of some other kind of electrical problem in the car.

I'm wondering if anyone else has heard similar noises from their Toyota, or has any further insight on this. Anyone?

Can someone point me towards a GUI noise generator for the mac?

snarfodox — Thu, 01 Sep 2005 10:11:59 -0800

Can someone point me towards a GUI noise generator for the mac? I've been generating white, pink, blue and violet noise from the command line. I'd like to shift between them gracefully and I'd like to be able to corrupt them a bit on the fly. Killing the CLI process and restarting it with different parameters makes for a silent pause and even overlapping multiple processes makes for audible unpleasantness as one sound is abruptly terminated. Does anyone know of something I can use? Please help save me from Xcode.

How can I make my stereo quieter?

bcwinters — Mon, 15 Nov 2004 08:29:08 -0800

How can I make my stereo quieter? [MI] I have a Harman Kardon receiver (sort of an ordinary home model with a bunch of regular RCA inputs and two sets of speaker-wire outputs) and a pair of Fisher speakers that date from the 70s that my dad gave me. I have a bunch of regular devices running into a switcher box that then feeds into the stereo -- the TiVo, the PS2 & GameCube, my Mac, etc.

The problem is that even the line-level inputs like the TiVo are WAY too loud since I moved to an apartment with a smallish living room. I can't even turn the volume halfway between zero and one without feeling like I'm going to wake the dead, especially in the evening. The speakers sound great and warm and I don't really want to replace them. I am not an audiophile although I do care about halfway decent, natural sound.

I bought some highly-rated bookshelf speakers a while ago, thinking they would have a lower overall output, and they sounded so tinny compared to the floor speakers I was used to that I had to return them. Today I searched on Google for something to reduce or limit the volume and all I could find were sort of audiophile-ish devices that cost $200 or more.

Can anyone recommend some kind of not-that-expensive device I can stick between the stereo and the speakers (or between the switcher box and the stereo, or whatever) that will reduce the overall volume so I can have more control over the sound? Thanks!

Shoot them with silence.

mert — Thu, 19 Aug 2004 14:49:58 -0800

My recent experience at work has led me to wonder whether there is any sort of personal noise cancellation gun? I envision a device or appliance that you can point at someone obnoxious to negate them using noise cancellation technology.

How can I make mp3s meant to lead into each other actually lead into each other without pausing first?

PinkStainlessTail — Sat, 26 Jun 2004 17:06:21 -0800

Ripping a CD that has tracks that lead into each other and then converting to MP3 has presented me with a problem. When I try to play the MP3s back in order there's a slight stagger when the next track starts (not a crossfade or optional pause), where on the audio CD the transition would not be noticeable. I'd like to either eliminate this error and keep the individual MP3s or rip the CD as one big audio file and convert that to one big MP3. Advice? [specs inside] Ripper tried: CDex
Players tried: QCD and Winamp5
WinXP home, Athlon XP 2400+

Home recording studio questions

weston — Thu, 01 Jan 2004 13:34:21 -0800

Home recording studio questions: (1) What to do about sound source with a noise problem (sounds like a bad ground loop) and (2) building some approximation of an isolation booth. [more inside]
(1) I've got a Chet Atkins Electric Classical and a Hughes & Kettner amp combo that I like quite a bit. There's a low hum that gives me pause when recording, though, and it's especially bad if I use the XLR direct out on the back of the thing. I could mic the amp cabinet, but I'm a little bit afraid to do that because the walls/ceiling are sortof thin where I live and there's lots of ambient noise. I'm pretty sure the amp is the problem, as I don't get the noise if I just take the guitar straight into an M-Audio pre-amp (which is probably an audio atrocity, but it works). I thought of trying to record the hum and inverting it and trying to keep that synced with the actual track, figuring superposition would mean I'd get reduced noice. I have not tried a narrow notch filter yet.

(2) So the other things I could do is build some kind of isolation booth. I can't really modify the place, so it has to be freestanding and I don't have a lot of room anyway, so it has to be something I can set up and take down and store without too much trouble. My first thought was a PVC pipe frame around which I could hang some quilts. Any others?