Questions tagged [spectrogram]
A spectrogram is a time-varying spectral representation (forming an image) that shows how the spectral density of a signal varies with time.
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Math.Net and alglib returning different FFT outputs by default
I am developing an application in C# with spectrogram drawing functionality.
For my fist try, I used MathNet.Numerics, and now I am continuing to develop with alglib. When I changed from one to the ...
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21 views
Help needed for Matlab Spectrogram plot
I am trying to plot a spectrogram using Matlab.
Basically what I need is to have:
-time in the X axis
-Velocity in Y axis
-Intensity is the current (in pico Ampere)
Basically, I want to create a ...
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8 views
What features capture the semantics of a sentence from a gien audio?
I have been thinking lately and looking up on what could be the possible features that capture the semantics of an audio and came across MFCC: MFCC features represent phonemes (distinct units of sound)...
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34 views
Comparing spectra from hyperspectral images
I extracted the mean spectra of regions of interests of different tissues from hyperspectral images. How to compare those spectra by the difference of their reflectance and their spectral behavior (...
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97 views
What's the theoretical bandwidth?
A radio signal is sampled at $f_{s}=5512$ Hz, and $n=2^{14}=16384$ points are used in the FFT to display it as a spectrogram.
The frequency resolution is $\frac{f_{s}}{n}=0.33642578125$ Hz/point, ...
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41 views
Spectrogram of an executable binary [closed]
One of the approaches I have been searching so far is the application of utilizing Neural Network to classify Spectrogram images, which is heavily used in speech recognition.
I am conducting an ...
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14 views
Normalize a Mel-Spec over which axis?
I have to find out: how to normalize a Mel-spectrogram.(for mashine-learning purpose) However, I don't know which axis has to be transformed.
The spectrogram S is of shape (m x n) where n are the ...
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18 views
Power spectral density of surface roughness
I am currently working on understanding how visually and intuitively the power spectral density is the fourier transform of the autocorrelation of a signal. I was wondering if anyone had a good ...
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24 views
Some confusion about calculating spectrogram
I am new to DSP and i have a question because it is not the same as theory.
I need to get spectrogram of wav file and feed it to CNN. I have used scipy.signal to get spectrogram.
I know spectrogram ...
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39 views
Why does a strange frequency appear in this image?
Here is an image of a filter bank spectrograph, where the main signal is at 2.5kHz and the high signal is at 21.5khz,
What is the high frequency signal? I doubt that birds can make frequencies above ...
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How to find the Pitch of a utterance using narrowband spectrogram
Can anyone tell me how to find the pitch of an utterance from it's narrow band spectrogram? I am pretty new to the speech processing domain so any help is appreciated.
P.S. I need methods to estimate ...
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Bandpass Experiment: Weird graph! amplitude mismatch?
Why is this generic BP filter seem to magnifying amplitudes when I run it at lower sample rates? The bass range seems to 32 times louder at 1275 Hz (44.1 kHz / 32) than at 44.1kHz?
Here is a graph of ...
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55 views
Feature Extraction of Insect Sounds
First of all, forgive me if I sound stupid. I am still learning Audio Processing.
So I am trying to make a machine learning model for detecting a specific insect through sound.
Here is a sample raw ...
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26 views
Modified STFT resynthesis
This post is basically a follow-up to my recent question, which I asked here How to deal with phase incoherence issues after manipulating a signal in the frequency domain?
In short, I'm modifying the ...
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1answer
42 views
Compensate for microphone?
I have trained a machine learning model to recognize a specific audio event from mel spectrograms, and it works pretty well on a hold-out test dataset. I now want to run the model on a device and feed ...
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11 views
Fluctuations of spectral density estimates
I have seen in a few papers things like :
or
Without ever seeing the assumptions which are made, and of course no justifications. Does somebody know why it is a valid approximation to make ?
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how to reconstruct an phase information from the magnitude spectrogram
I need to recreate the phase of a spectogram of magnitude and when inverse fourier, that the sound is understandable and not pure noise
Observe these softwares
https://photosounder.com/
http://...
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103 views
Old style signal processing?
I am wondering if "an array of overlapping band-pass filters" it is 'mostly' equivalent to a Short-Time Fourier transform. See this (figure down), where $s(t)$ is the signal;
LPF a second-order low-...
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176 views
Phase information of a signal when creating a spectrogram
Sorry for the uninformed question but I need some help understanding this. I'm trying to understand what phase information is and it would be very helpful if someone could correct my understanding of ...
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30 views
Python mixing, filtering, and decimation. I'm a rookie!
Background:
I have a spectrogram of window length 256 time frames and window width 1024 frequency bins. It initially took IQ using 10*log_10(magnitude) to output this spectrogram with window overlap ...
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1answer
203 views
High resolution spectrograms
I have a recorded audio signal that I would like to convert into spectrogram with the highest possible yield of information.
The audio clips I am working with is about 30 ms long and contains ...
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2answers
66 views
Augmentation for EEG signal classification using Deep Learning
Augmentation is a technique that we use in deep learning for expanding the training dataset. It includes different ways of modifying an image and adding it to the training dataset. My question is if ...
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34 views
Spectrogram using SciPy - bad scaling of the timeline [duplicate]
I have a real value signal which has 197 samples (every 1 second). I made its spectrogram using the SciPy library:
...
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Why can ARSS not recreate audio from a spectrogram without sounding muffled?
Why do ARSS and all audio to spectrogram then back to audio program's create audio files that sound muffled?
I know their is some physics and math with the short-time Fourier transform and etc. I ...
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3answers
135 views
Using different algorithms/formulas to create spectrograms
On the internet, I have seen people use Matplotlib/Python and short-time fourier transformations to create spectrograms. Are their other formula/algorithms to create spectrograms? And are they ...
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247 views
What are some alternatives to Spectrogram charts? [closed]
Spectrogram renders of audio are limited in their representation of audio. For example, one could not use a Spectrogram to re-render the original audio.
What are some alternatives to Spectrogram ...
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184 views
Spectrogram Time Resolution with Overlap
I understand that the time resolution of a spectrogram with no overlap is the sampling frequency divided by the window length. How does this change with, say, 50% overlap? Does this double the time ...
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178 views
How to interpret these MP3 spectrums?
Recently, I found I had this song duplicated in my music library, but when listening to them I noticed one version was of noticeably higher quality than the other despite both claiming to have a ...
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31 views
When do phases not exist for spectrograms?
I have been reading a paper on the "Single pass spectrogram inversion"
and I came across this in the Introduction part.
In many applications, the analysis and modification of the Short-Time
...
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1answer
68 views
Finding where signal is showing some (unknown) periodicity
I have readings of the vertical displacement of someone over time, as in the picture below:
At some points in time, the person will be exercising or jumping up & down, creating more or less ...
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40 views
Optimizing Spectrogram Parameters
I'm looking for references that explain the trade-offs between more averages with shorter fft sizes or longer fft sizes with fewer averages when generating a spectrogram to perform energy detection of ...
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1answer
346 views
Spectrogram of a single tone complex signal has two dark lines?
I am trying to plot the spectrogram of a complex signal I generated. I have written code to generate this signal and plot the spectrogram. It works. However I see that there are two dark lines present ...
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2answers
370 views
audio spectrogram normalization
I am performing language classification from audio signals using mel-spectrograms as my inputs for a ResNet. It works well as long as all of my audio data from different languages is from the same ...
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407 views
How to convert a spectrogram back to a signal [duplicate]
I'm converting a signal to a spectrogram, manipulating that (nonlinear stuff), and then want to use the modified audio signal. I can make it so the segments are not overlapping, but am unsure how to ...
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26 views
Spectrogram of chirp sequence radar signals
I am confused as to whether SFFT makes sense to process chirp sequence signals. The radar fires up a sequence of 100 linear ramps with that are only interrupted by the very short period in which the ...
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1answer
174 views
Spectrogram power/magnitude normalization in analogy with image intensity normalization
In analogy with the 8-bit grayscale image color depth, in which the intensity of a sample pixel is normalized to a value between 0 and 255 by taking into account the minimum and maximum intensities ...
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finding harmonics from fundamental
https://s3.amazonaws.com/izotopedownloads/docs/rx700/en/interactive-tools/index.html#selection-tools
From the above link, under the "Magic Wand" tool description, how does that algorithm work?
In RX,...
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65 views
Normalizing vectors to be the same size to retain PSD data
Context:
PSD=periodogram(y) in MATLAB gives the PSD (power spectral density) estimate of a sound-source signal. I want to find the local maximum within 3 different ...
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458 views
How to Extract frequency bands from Short-time Fourier Transform?
I am reproducing the results reported by the author in a research paper. In which he takes the STFT of EEG signals. The input data has a shape of (1 X500) and I used Scipy library built-in function to ...
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67 views
Extracting audio from picture of time-domain signal
I saw this nifty art thing where they dress up the time-domain audio signal in some pretty way.
https://www.etsy.com/ArtbloxShop/listing/621561709/sound-wave-art-custom-soundwave-print
My question is ...
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62 views
How to classify the movement type of a target into two categories(direct motion or else) by using a doppler radar?
How to classify the movement type of a target just into two categories(one is direct motion which is almost straight line movement and the other is anything else) by using a doppler radar with a ...
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1answer
2k views
How to go from wav file to spectrogram back to wav file in python?
Close to this question but different : Wav To Spectrogram, Back To Wav
I already posted this on StackOverflow(https://stackoverflow.com/questions/54743968/how-to-go-from-wav-file-to-spectrogram-back-...
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442 views
Recover Audio from Spectrogram Image
I have applied transformation(Constant Q Transformation) to my audio time domain signal, this gives me Frequency vs Time representation. Now, the CQT values consists of complex values(84*260), but ...
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52 views
Scipy Welch's gives different first element
I've re-implemented Welch's method and want to compare it to scipy.signal.welch. However, the first two and last elements of the resulting array are different.
My ...
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2answers
56 views
What is Causing a Noise Signal in USB Audio Recording?
I am experiencing the following peculiar noise signal when recording from my Behringer Xenyx Control 2 over USB.
There is frequency at around 2293 hz as show:
And over time, it produces the ...
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184 views
How can I calculate the Number of bins per octave?
I am trying to calculate the Constant Q Transform for Monophonic audio using Python.
The Python has the library to calculate the CQT , the default value of num_bins_per_octave is 12.
How would one ...
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2answers
648 views
How to calculate the PSD from the complex calculated STFT?
I have calculated the STFT with scipy python library:
...
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How to know the time of my window to calculate the STFT with python knowing only the length?
I am trying to implement a work presented in an IEEE paper where they have mentioned that the STFT was performed on the signal measurements to obtain a spectrogram with no overlap window of 3 min :
I ...
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2answers
97 views
Fourier Like Spectral Analysis with Uneven Intervals and Redesigned DFT Matrix
I intended to use a discrete Fourier transform (DFT) on a time series sampled at uneven intervals. What I did was to calculate a DFT matrix where the elements are the values at the uneven locations ...
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591 views
Audacity Spectogram view: how to see exact frequency and intensity under the cursor?
In the Spectogram view, simply clicking anywhere with the selection tool gives a vertical line to the top ruler, and shows at the bottom the exact sample, H:MM:SS, or other time coordinate you'd want.
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