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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Order of operations when creating a spectrogram

Signals noob here! I'm dipping my toes into your world by trying to recreate the Shazam algorithm, and I have a quick practical question: When creating a spectrogram, is it better to take in a whole ...
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Reconstructing audio from a given spectrogram and phase data

I have 2 seperate files called: spectrogram and phases. Spectrogram contains magnitude information of audio and phases contain the phase information of each windowed area. I need to reconstruct the ...
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Interpretation of fft plot

I am trying to understand how to interpret a spectrogram image plot: (1) what does the yellow band and its corresponding color code with a high positive value indicate? There are so many yellow bands ...
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Faded line in spectrogram for a chirp

I've generated this spectrogram using wavelet convolution. The chirp is generated like so: ...
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How can a CNN account for spectro-temporal constraints in neural data?

What are there the best ways to leverage the unique "geometrical" constraints of spectro-temporal signal representations (architecture, filter shapes, data augmentation, etc.)? For example, ...
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How to remap center frequencies of a mel filter bank?

I'm trying to implement vocal tract length peturbation in python (Vocal Tract Length Perturbation (VTLP) improves speech recognition. Navdeep Jaitly, E. S. Hinton, Published 2013, Computer Science) by ...
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Does downsampling increase the resolution of frequencies?

I am currently working in MATLAB and had to downsample a .WAV file (I used the downsample function in MATLAB) to 44.1 kHz. However, when I compared the two spectrograms of the original signal vs the ...
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Matlab spectrogram

I have to do 'inverse engineering' with piano sound and find sequence of frequencies in it. I have to use spectrogram() and adjust parameters. I set window length as 512 to see more frequencies and ...
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Spectrogram parameters piano sound

I have to do 'inverse engineering' with piano sound and find sequence of frequencies in it. I have to use spectrogram() and adjust parameters but my problem is that I don't know how. I set window ...
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log spectral distance interpretation

I am using the log spectral distance (LSD) as a metric to evaluate signals. I have 2 completely different signals pairs I compared. Pair (A,B) : signal A as pretty similar to B. There are only very ...
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How to get spectrogram of an array in MATLAB

So.. I want to make spectrogram out of 4 signals that i need to add in array. When I add them in array, it looks like this s=[x1 x2 x3 x4] or with values: ...
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Can someone help me this db transform applied on melspectogram?

I have read some audio processing codes written in Python : ...
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How to Find spectral Peaks from 2D array of Spectrogram? [closed]

I have computed a Spectrogram 2D array as : How to develop a spectrogram (2D array) from audio signal? Now, I want to find spectral peaks to find the respective temporal displacement. In python using ...
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How many things can they be done with a spectrogram?

I found some things that can be done with a spectrogram. filter frequencies by setting the bins to zero observe what frequencies make up the signal. observe the energy or amplitude of each frequency, ...
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Why does the griffin lim algorithm work?

the griffin lim algorithm works to reconstruct audio from a magnitude spectrogram, but i don't understand how reusing the same spectrogram every iteration with noise can produce decent sound How from ...
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Running a sox spectrogram on a bandpass filtered wav file

Let's apply a 400-2000Hz bandpass filter on a respiratory .wav file: sox audio1.wav audio1.bandpass.wav sinc -t 10 400-2000 Now I'd like to generate a ...
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131 views

How to develop a spectrogram (2D array) from audio signal?

I have developed a spectrogram in Python using Scipy.Signal.Spectrogram. But I need a complete understanding of data. Here I am not asking about plotting and color ...
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How to get coordinates(x(time),y(frequency)) of spectral peaks from spectrogram?

I have created this spectrogram from a wav file. Please have a look: As it can be observed clearly that my somewhat spectral peaks are visible. I want to get the x = time, y= frequency of these ...
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Calculating the spectrogram of the center of pressure time series in human standing balance

I have some biomechanical data of a few subjects standing on a force plate. The center of pressure along the x and y axes was measured. The total time of measurement was 30s and the sampling frequency ...
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Is mean squared error or absolute error on two spectrograms of two different wav files enough to compare how similar they are?

I've been working on a genetic algorithm to figure out how to play a guitar chord just by listening to it. I have it all working now, but the system I am using to compare how 'similar' a guess is to ...
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How to get Spectrogram after fft in matlab?

I have many EEG signals which record at 100 Hz. I use FFT on them with fft Matlab toolbox. Now I wanted to get a Spectrogram. As I searched and read a lot, I figure that I should window my signal and ...
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Discrete and Continuous Signals

I am new to the signals area and have been reading through a lot and have some questions. Suppose I have a saved audio file on my computer, .wav file. I can view the time domain of the signal by ...
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26 views

What is the relation between PCM amplitude values and the values in a Spectrogram?

I am curious to know the relation between the 16-bit amplitude values in the PCM-encoded signal and the values inside the corresponding spectrogram. I am using Scipy reading a 44100-sample rate song: ...
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Please, help me interpret my Simulink simulation of AM. Why does carrier not appear in the spectogram?

Carrier is 2 * pi * 25, modulating signal is 2 * pi, all the amplitudes are 1s and zero phase. I realized that I could add a sine wave right at the end. I get a carrier in frequency domain, but my ...
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106 views

How can I improve the resolution of a spectrogram of a low-frequency signal with high sampling frequency (Python)?

Imagine you have signals $x_1(t)$ and $x_2(t)$ that contain a limited number of periods of low frequency oscillations and are sampled at 44100Hz (coming from an external source) and you want to obtain ...
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Why should one choose the maximum as reference for power-to-decibel conversion?

I have seen that one converts the amplitude to decibels through: $\text{dB(S)}=10 \text{log}_{10} \big(\text{S/ref}\big)$, where $\text{S}$ is the output of a STFT and ref the reference value for the ...
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Time series in spectrogram() and spectrum()

I'm trying to create an order map for order analysis from my accelerometer data. To do that I want to resample my acceleration data and their time stamps in python. I found ...
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130 views

Why are MATLAB and matplotlib spectrogram value different?

I'm doing a signal processing to put data into my neural network. I noticed a difference between MATLAB and Python ...
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48 views

Frequency and Order maps

I'm new to python and I'm using it to analyse accelerations from an accelerometer ie. vibration analysis. For that I need to plot 2 types of diagrams: 1) Frequency map; frequency and time on the axis ...
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57 views

What is the value range of log magnitude spectrograms?

I'm quite new to this field and have a probably rather basic question: Is there an upper bound for the values in a log-magnitude spectrogram generated like this: ...
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Is sparse dictionary learning just a subset of non-negative matrix factorization?

I saw some people argued that their method should be called sparse dictionary learning or NMF. What are the differences between these two terminologies? If the dictionary is given or fixed, the ...
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Energy Detection Sensitivity Comparison

In the area of broadband spectrum sensing, there are multiple methods used to detect energy. Two common methods are: Energy detection in the time domain (matlab example) Spectrogram (often defined by ...
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Frequency contour detection in spectrogram

I have an image of a spectrogram and I wish to detect the tracks/contours of prominent frequencies present in the spectrogram. In the end, I want to be able to get various prominent curves from the ...
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Spectrograms in Short-time Fourier Transform

I was watching this video, https://www.youtube.com/watch?v=NA0TwPsECUQ and the information that was displayed at 4:30 didn't make sense to me. The original time domain signal was recorded at 44100 ...
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49 views

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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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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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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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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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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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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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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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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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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41 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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62 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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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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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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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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