Strange pop heard but not seen

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philipus
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Strange pop heard but not seen

Post by philipus » Thu Sep 09, 2021 8:55 am

Hello

I've used Audacity for several years on and off for very simple processing to make my own ringtones and have usually been able to solve problems with the use of the excellent online help file. But this time I'm stumped and so registered here at the forum. So this is my first post.

I recorded a tone from my Apple Watch using Voice Memos on my iPhone. I know, not the best solution but I managed to get a fairly clean recording, which I further cleaned up by using the Noise Reduction filter and by adding silence between the beeps. The beeps are simple Morse code, long, short, short, long. Here is the recording, exported as mp3.
20210909 095050.mp3
(7.87 KiB) Downloaded 33 times
Strangely enough I hear a sort of clicking or popping sound in the short beeps, but I don't see any spike or such in the waveform. I copied and pasted one of the beeps over the other so both short beeps are identical and look like this:
audacity.png
audacity.png (34.57 KiB) Viewed 1541 times
Is it a simple case of garbage in garbage out and that I should try to re-record, or is there some way to find out where in the waveform the offending sound is?

I looked in the forum rules and didn't see anything forbidding uploading such a recording so I hope I'm not breaching any rules, but do feel free to let me know of course.

Thank you kindly in advance
Philip

steve
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Re: Strange pop heard but not seen

Post by steve » Thu Sep 09, 2021 9:11 am

Here I zoomed in on the end of the second beep.
Observe how the waveform abruptly snaps to zero at the end of the beep - that will sound as a click.
Attachments
First Track001.png
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kozikowski
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Re: Strange pop heard but not seen

Post by kozikowski » Thu Sep 09, 2021 9:32 am

not the best solution
But not the worst one, either. I can get a very respectable voice recording with my iPhone. Did you search out the quietest room or location for the recording? You are creating a post-production nightmare by choosing a room with traffic noises, air conditioning whurr, refrigerator hum, clock ticking, echoes, reverb, music system, and other sound trash.
adding silence between the beeps.
Generate > Silence?

That may be the first problem. You can't just start and stop tones like throwing a switch. You have to fade them in and out. If you don't they will make ticking or popping sounds at both ends and the damage may or may not show up on the timeline blue waves.

I would re-record the work. Get in your car and drive somewhere quiet. Cars can make remarkably good sound studios.

Crawl under heavy blankets in bed and do it there (the recording, that is). There is an explainer video where someone turned his trashy-sounding bathroom into a recording studio by throwing a heavy blanket over him and his microphone.

The iPhone records memos from the bottom (next to the cable connection), so that's how to aim the iPhone.

Koz

steve
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Re: Strange pop heard but not seen

Post by steve » Thu Sep 09, 2021 9:51 am

philipus wrote:
Thu Sep 09, 2021 8:55 am
which I further cleaned up by using the Noise Reduction filter and by adding silence between the beeps.
For cleaning up a recording of Morse Code, it would probably be better to use the Noise Gate effect: https://manual.audacityteam.org/man/noise_gate.html
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)

kozikowski
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Re: Strange pop heard but not seen

Post by kozikowski » Thu Sep 09, 2021 3:14 pm

cleaning up a recording of Morse Code
In my opinion, the Morse Code character isn't that important. This is a theatrical recording and theatrical rules apply.

I used to "speak" Morse and even through multiple passes, I couldn't understand the code. I don't think there is a code. I think this is a musical performance.

Koz

philipus
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Re: Strange pop heard but not seen

Post by philipus » Sat Sep 11, 2021 3:22 pm

Thank you very much Steve. I hadn't seen this.
steve wrote:
Thu Sep 09, 2021 9:11 am
Here I zoomed in on the end of the second beep.
Observe how the waveform abruptly snaps to zero at the end of the beep - that will sound as a click.

philipus
Posts: 3
Joined: Thu Sep 09, 2021 8:41 am
Operating System: macOS 10.13 High Sierra

Re: Strange pop heard but not seen

Post by philipus » Sat Sep 11, 2021 3:25 pm

Thank you for the encouraging words. Yes I used Generate > Silence so that may be the culprit, or possibly part of it, judging by the abrupt end to the waveform Steve showed above.

I'll try a new recording in an even quieter room.

Cheers
Philip
kozikowski wrote:
Thu Sep 09, 2021 9:32 am
not the best solution
But not the worst one, either. I can get a very respectable voice recording with my iPhone. Did you search out the quietest room or location for the recording? You are creating a post-production nightmare by choosing a room with traffic noises, air conditioning whurr, refrigerator hum, clock ticking, echoes, reverb, music system, and other sound trash.
adding silence between the beeps.
Generate > Silence?

That may be the first problem. You can't just start and stop tones like throwing a switch. You have to fade them in and out. If you don't they will make ticking or popping sounds at both ends and the damage may or may not show up on the timeline blue waves.

I would re-record the work. Get in your car and drive somewhere quiet. Cars can make remarkably good sound studios.

Crawl under heavy blankets in bed and do it there (the recording, that is). There is an explainer video where someone turned his trashy-sounding bathroom into a recording studio by throwing a heavy blanket over him and his microphone.

The iPhone records memos from the bottom (next to the cable connection), so that's how to aim the iPhone.

Koz

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