Record high pitched sound (long post, but please help)

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Record high pitched sound (long post, but please help)

Permanent link to this post Posted by Pahans » Tue May 10, 2016 4:53 am

Hello,

I'm fairly new to Audacity and quite the noob, but I think I've managed to learn the basics. I downloaded the program in order to record a high frequency sound that comes from the output of my laptop and into my earbuds.

I tried to have the problem fixed, but the guys at the repair shop couldn't hear the sound. This is because the sound is very faint and high pitched. It was supposed to be a free warranty repair, but since they deny that there's any fault, I'm left with the bill for diagnostics and shipping costs :( Personally I hear the sound clearly and have to listen to a tinnitus type sound whenever I watch movies or listen to music.

---

So I need to prove that this sound actually exists. I was thinking that I could record it and boost the volume, so that's what I tried. I connected a male-to-male jack from the output to the input and recorded the sound with Audacity. I successfully captured the sound, however there's a lot of static noise when I turn up the volume, which masks the sound. The static isn't present/audible normally.

I tried the frequency analysis to visually prove the sound's existence, and there are spikes at around 7 kHz and 14 kHz. I used the notch filter to remove these frequencies, and sure enough the sound disappeared. However I'm not sure the results are conclusive, because my other computer also have spikes at 7 and 14 kHz, but that one has no high pitched sound.

I also tried to isolate the sound by using the notch filter (removing all but the 7 and 14 kHz frequencies), but it seems like when I remove the frequencies next to 7 and 14 kHz, these frequencies weaken as well.

---

These are the results of my experiments:

(Turn down your volume :!: )

Sound clip 1 (with high frequency sound):
https://clyp.it/eqmcu3r0?token=e907b783636396017f01d65ec48dad22
The sound can be difficult to hear through the static, but it's there.

Sound clip 2 (same recording, but without 7 and 14 kHz frequencies):
https://clyp.it/trqghe5k?token=41cc9e325a860a11d5c16ac6cf9f9279
Only static.

Screenshots:
http://imgur.com/a/lxQhF
The first six pictures are previous recordings for which I have no corresponding sound clips. The next 4+4 pictures match sound clips 1 and 2 respectively. Unlike the first six recordings, these are boosted beyond just turning the volume up in Audacity (which is why they're so fat). I don't really know how it happened, it wasn't intentional, but it occured when I exported and saved the files and then dragged them back to Audacity.

---

So is there a way to record the high frequency sound without static noise? Is there a way to isolate the sound / remove the static noise? Is there a way to visualize the sound in a conclusive way?

And btw, why are the frequency analyses in negative dB? :?

Sorry for the long read, but I really hope someone can help :) Additionally, I hope this is the appropriate forum.

Cheers,
Pahans
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Re: Record high pitched sound (long post, but please help)

Permanent link to this post Posted by steve » Tue May 10, 2016 8:13 am

Please post a short sample (just 4 or 5 seconds) in WAV format to the forum.
The sample should be the raw recording with no additional processing at all. Just "record, select, export selection".
See here for details about posting an audio sample: viewtopic.php?f=49&t=72887
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Re: Record high pitched sound (long post, but please help)

Permanent link to this post Posted by cyrano » Tue May 10, 2016 9:09 am

If you have "Y" jack cable, try to record as you did, but with the headphones attached too.

Due to the higher impedance of the input, the recording shows static and noise. If you put headphones in parallel, this could go away.

And maybe the input is a microphone input, in which case it is too sensitive and Windows might try to "enhance" the sound.
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Re: Record high pitched sound (long post, but please help)

Permanent link to this post Posted by Trebor » Tue May 10, 2016 2:22 pm

Pahans wrote:... Is there a way to visualize the sound in a conclusive way?

Spectrogram view ...

Audacity waveform & spectrogram of ''eqmcu3r0''.png
Audacity waveform & spectrogram of ''eqmcu3r0''.png (300.88 KiB) Viewed 640 times

The constant ~7kHz tone is on both channels , but the ~14kHz harmonic is only on the right channel .
[ NB: 14kHz is too high-pitched for most people to hear, no matter how loud it is.
7kHz , if loud enough, will be audible by most and sound like tinnitus ].

If you play the track at half-speed the strong peak @ ~14kHz on RHS becomes a loud ~7kHz whine.

Pahans wrote: ... my other computer also have spikes at 7 and 14 kHz, but that one has no high pitched sound.

If both computers are in the same location possibly both are picking up the same interference [EMI].
Alternatively if your both of your computers been upgraded to Windows 10, maybe you need to update audio-driver-software compatible with Windows 10 , or run the old audio-driver in "Windows compatibility mode".
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Re: Record high pitched sound (long post, but please help)

Permanent link to this post Posted by Pahans » Sat May 14, 2016 10:17 pm

Hi guys!

I'm sorry that I haven't been following up on my own thread - I've been out of town (and quite busy) for a while. But I appreciate your responses, they've been very useful, so thank you! :)

steve wrote:Please post a short sample (just 4 or 5 seconds) in WAV format to the forum.
The sample should be the raw recording with no additional processing at all. Just "record, select, export selection".
See here for details about posting an audio sample: viewtopic.php?f=49&t=72887


Here you go :) The recording titles are pretty self-explanatory; four of them are from my bad pc (included in this post), the others are from my other pc for comparison (I'll add them in the next post (upload restrictions)). For some reason, the 7 and 14 kHz spikes in my control pc only occur occasionally :? As you can see, they're only present in one of the recordings, while in the past there have been more. I have no idea why, but it might have to do with the hard drive working.

I've made recordings using both Wasapi, MME and DirectSound, although I've got no clue what the differences and applications are :lol: I just thought the more information the better.

---

cyrano wrote:If you have "Y" jack cable, try to record as you did, but with the headphones attached too.


Do you mean a 2 male + 1 female cable? I didn't have that, but I had a 1 male + 2 female cable. I connected a separate 2 male cable to one of the female ends (effectively making it a 2 m + 1 f) and then I plugged it into the input/output with headphones attached. However, it didn't seem to make much of a difference to the recording =/ Does it matter whether I put the spliced end (with the headphones) into the input or the output?

---

Trebor wrote:The constant ~7kHz tone is on both channels , but the ~14kHz harmonic is only on the right channel .


Is that one of my pictures? I can't see the 14 kHz line in any of my pictures on Imgur (that's the line with no arrow, right?). How did you produce that?

Trebor wrote:[ NB: 14kHz is too high-pitched for most people to hear, no matter how loud it is.
7kHz , if loud enough, will be audible by most and sound like tinnitus ].


I have to disagree with you there. From what I've learnt, humans can hear up to around 20 kHz, and in some cases even more if you're young enough. Personally I tried this https://www.youtube.com/watch?v=VxcbppCX6Rk test on Youtube, and I can hear the 19 kHz sound perfectly fine if it's loud enough. I ran the clip through Audacity as well, so I can confirm that the frequencies are accurate.

Trebor wrote:If you play the track at half-speed the strong peak @ ~14kHz on RHS becomes a loud ~7kHz whine.


Thank you for this, that was very helpful! :) The high pitched sound became much louder relative to the static when I slowed the recording down.

Trebor wrote:Pahans wrote:
... my other computer also have spikes at 7 and 14 kHz, but that one has no high pitched sound.

If both computers are in the same location possibly both are picking up the same interference [EMI].


I think I can rule out interference. For some reason, my old computer doesn't always have the spikes (like I wrote above), contrary to what I believed in my first post. Also I've done recordings on the problem computer outside the building; same story. Not to mention that it didn't use to have a high pitched sound before.

Trebor wrote:Alternatively if your both of your computers been upgraded to Windows 10, maybe you need to update audio-driver-software compatible with Windows 10 , or run the old audio-driver in "Windows compatibility mode".


Thanks for the tip, but I don't want it fixed, because I need to prove that there's a fault in order to avoid the repair bill ;)
Attachments
Take 1, Wasapi.wav
(1.2 MiB) Downloaded 20 times
Take 2, Wasapi.wav
(990.04 KiB) Downloaded 15 times
Take 3, DirectSound.wav
(1.09 MiB) Downloaded 17 times
Take 4, MME.wav
(1.58 MiB) Downloaded 15 times
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Re: Record high pitched sound (long post, but please help)

Permanent link to this post Posted by Pahans » Sat May 14, 2016 10:21 pm

Recordings from control pc.
Attachments
Control pc take 1, spikes present, Wasapi.wav
(1012.54 KiB) Downloaded 16 times
Control pc take 2, spikes absent, Wasapi.wav
(931.92 KiB) Downloaded 16 times
Control pc take 3, spikes absent, MME.wav
(876.17 KiB) Downloaded 15 times
Control pc take 4, spikes absent, DirectSound.wav
(1013.71 KiB) Downloaded 15 times
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Re: Record high pitched sound (long post, but please help)

Permanent link to this post Posted by steve » Sun May 15, 2016 10:41 am

Pahans wrote:I have to disagree with you there. From what I've learnt, humans can hear up to around 20 kHz, and in some cases even more if you're young enough. Personally I tried this https://www.youtube.com/watch?v=VxcbppCX6Rk test on Youtube, and I can hear the 19 kHz sound perfectly fine if it's loud enough. I ran the clip through Audacity as well, so I can confirm that the frequencies are accurate.

I'm going a little off-topic here, but it's still relevant ...
Human hearing range is usually quoted as 20 Hz to 20 kHz. There have been no cases (in proper scientific / medical tests) of anyone being able to hear above 20 kHz. Young people are sometimes able to detect sound up to about 20 kHz, but it's not quite "hearing" in the sense of hearing "normal range" sounds. 20 kHz is the very top of what anyone can detect: "yes there's something there - a sort of sensation in my head"

Running hearing tests on consumer equipment will often be misleading. When very high frequencies are played at high volume through speakers or headphones, it will often create resonant harmonics at lower frequencies than the actual signal - for example, playing a 19 kHz sound loudly through normal headphones could produce frequencies well below 19 kHz as well as the actual 19 kHz tone. To test properly you need to use proper medical equipment to be sure that isn't happening.

14 kHz is audible to some people, but for someone with high frequency hearing loss it may not be. Very high frequencies tend to be more difficult to hear when there is other high frequency noise present.
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Re: Record high pitched sound (long post, but please help)

Permanent link to this post Posted by Trebor » Sun May 15, 2016 2:51 pm

Pahans wrote:
Trebor wrote:The constant ~7kHz tone is on both channels , but the ~14kHz harmonic is only on the right channel .

... I can't see the 14 kHz line in any of my pictures on Imgur (that's the line with no arrow, right?). How did you produce that?

The default spectrogram on Audacity only shows up-to 8000Hz , but you can zoom-out to show the full frequency range , ( or change the maximum frequency in Audacity spectrogram preferences )

Pahans wrote:... Personally I tried this https://www.youtube.com/watch?v=VxcbppCX6Rk test on Youtube, and I can hear the 19 kHz sound perfectly fine if it's loud enough.


That YouTube [v=VxcbppCX6Rk], even when played at top 1080p "HD" quality , does not contain any audio above 16kHz ...
Waveform & spectrogram of YouTube v=VxcbppCX6Rk @ 1080p.png
Waveform & spectrogram of YouTube v=VxcbppCX6Rk @ 1080p.png (369.16 KiB) Viewed 623 times

The YouTuber has underestimated the limit the YouTube transcoding puts on the audio.
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Re: Record high pitched sound (long post, but please help)

Permanent link to this post Posted by Pahans » Mon May 16, 2016 6:51 pm

steve wrote:I'm going a little off-topic here, but it's still relevant ...

Please do. It's an interesting topic.

steve wrote:Human hearing range is usually quoted as 20 Hz to 20 kHz. There have been no cases (in proper scientific / medical tests) of anyone being able to hear above 20 kHz.

From Wikipedia: "Under ideal laboratory conditions, humans can hear sound as low as 12 Hz[6] and as high as 28 kHz". https://en.wikipedia.org/wiki/Hearing_range#Humans
(Sorry, I can't find out how to hide URLs in words.)
Source material:
http://scitation.aip.org/content/asa/journal/jasa/122/3/10.1121/1.2761883

I don't know if the study is proper science or not though, or maybe there's some technicality that I don't understand - I'd like to hear what you think. In any case, I think you're right that the higher frequencies are more sensations than actual sounds.

Trebor wrote:The default spectrogram on Audacity only shows up-to 8000Hz, but you can zoom-out to show the full frequency range

Cheers.

Trebor wrote:That YouTube [v=VxcbppCX6Rk], even when played at top 1080p "HD" quality , does not contain any audio above 16kHz ...

I'm probably not getting something, but this is the spectrogram/frequenciy analysis that I'm getting (recording through either microphone or speakers):
http://imgur.com/smFAXtS
The recording is of the 15-19 kHz part. What am I missing?

To return on-topic though. Ideally I'd like to remove all the noise and isolate the high pitched frequency (-ies) and turn up the volume - without slowing down the recording. That way the repair guys can't claim that the sound is "constructed" in Audacity by manipulating the clip (other than removing noise). Is this possible? Could one of you maybe use one of my clips and do this, or tell me how?
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Re: Record high pitched sound (long post, but please help)

Permanent link to this post Posted by steve » Tue May 17, 2016 9:07 am

Pahans wrote:From Wikipedia: "Under ideal laboratory conditions, humans can hear sound as low as 12 Hz[6] and as high as 28 kHz".

Wikipedia can be misleading, and in this case I think it is misleading.
Response to frequencies well above 20 kHz has been recorded when transmitted through bone conduction. In the tests referred to by Wikipedia, the test subject had their head "attached to a headrest" and tones blasted at them at 90 dB from 50 cm distance. This clearly does not relate to the common day to day experience that we refer to as "hearing". Going even higher in frequency and increasing the power, it would be possible to burn the subjects ears due to the thermal effects of ultrasound - sure the ultrasound would be "detected" by the subject, but would we call that "hearing"?
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