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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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Store the Spectrogram as Image in Python [on hold]

I want to store the STFT spectrogram of the audio as image. The code below shows a spectrogram to me as output, but when saved as image I get a different image. ...
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2answers
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Recommended resources for noise reduction

I know the question What Resources Are Recommended for an Introduction to Signal Processing (DSP)? and I have already read some general DSP books, such as Rick Lyons's "Understanding DSP," and also ...
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Spectrogram with square or non-square magnitude of STFT: power vs. magnitude

As seen in this question and answer, to do a spectrogram, it's common to plot either: the square magnitude $|\text{STFT}(\text{frame}, \text{bin})|^2$ ("power spectrum") the magnitude $|\text{STFT}(\...
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1answer
44 views

Calculating SNR from Frequency-time domain

I tried to analyse the time-frequency of specific appliances. As it shows in the following frequency-time graph I have High frequency noise from different appliances here. 4096 is the number of ...
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2answers
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Window length in matplotlib's specgram

In the paper about speaker verification I can read that Two quantities have to be set: the length of the window and the shift between two consecutive windows. For the length of the window, two ...
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1answer
36 views

Phase of a signal with multi delayed windowed (rectangular window) signal with different amplitudes

I have a signal $x(t)$ which is composed of multi delayed linear chirps with different amplitudes and phases but they share the same $w$ and $\alpha$, the signal can be expressed as follows: $$\...
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2answers
69 views

Spectrogram from scipy.signal with Python

To test the python spectrogram (from scipy.signal) , I've created a signal with 2 harmonics: 2 Hz and 8 Hz. Then I've added 50Hz noise and a trend (https://i.imgur.com/t1SnQck.png). I wanted to ...
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43 views

Log difference measure

Referring to this research paper: Drum Source Separation using Percussive Feature Detection and Spectral Modulation. In section III Temporal Estimation, equation 2 is the log difference of the ...
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1answer
36 views

How do I apply a binary mask and STFT to produce an audio file?

So here's the idea: you can generate a spectrogram from an audio file using shorttime Fourier transform (stft). Then some people have generated something called a "binary mask" to generate different ...
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27 views

spectrogram for high sample rates

I have a signal with the following characteristics. I’m using the following code snippet to get the spectrogram which does not seem right as I do not see a 10 MHz frequency bandwidth, which I know the ...
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21 views

Is there any relationship between the frequency band and row number of spectrogram [duplicate]

Can we derive some equation or relationship between the frequency band of the spectrogram and the row number of the spectrogram matrix. For example, if we have a spectrogram ...
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15 views

Teager-Kaiser Energy Operator based Spectrogram

I plotted a normal spectrogram for 3 recordings (left), and their TEO (or TKEO) based spectrograms (right). I wanted to understand/read the differences between the left and right pictures. I do ...
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36 views

Spectrum of received signal from radar fm-cw

I obtained actual data from a researcher, consisting of a matrix composed of several received signals from an up-ramp fm-cw radar. Wouldn't be reasonable to plot the spectrogram of a ramp up and ...
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1answer
37 views

What unit is the z axis of a power spectrogram of audio?

the question might seem dumb but since I tried it out and got values well above 2000 (watts?) it got me thinking... Check this out: ...
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1answer
51 views

1D signal to 2D spectrogram

I struggling at transforming a 1D breathing signal into 2D spectrograms, power spectral density as a function of time and frequency. Does anyone have an idea about that?
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1answer
47 views

nearest neighbor implementation matlab

I am trying to implement this research paper: I understand everything in the paper except the part about the nearest neighbors calculation (section 3). The only MATLAB function I can think of that ...
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61 views

How to manipulate output of Matlab's 'spectrogram' function for additional spectral analyses

all, I have an audio recording that contains several frequency-modulated elements (think animal calls like birds/bats). I have read this file into Matlab using 'audioread' and plotted the oscillogram ...
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2answers
46 views

Is there such thing as harmony independent timbre characteristic of a sound?

I was wondering if any of you know about any technique to extract a harmony (e.g. harmony in a shape of a chromagram) independent timbre characteristic of a sound frame. What I'm after is a version ...
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1answer
80 views

CMV: COLA constraint is not necessary

In the literature on the short-time Fourier transform (STFT) it is often stated or implied that the constant overlap-add (COLA) constraint must be satisfied in order for the STFT to be invertible. ...
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What is the difference between spectrogram and spectral envelope, if any?

I am working on different vocoders Griffin-Lim and WORLD. They use spectrogram and spectral envelopes respectively by definition. I wonder the difference between these two representations.
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60 views

How to determine the frequency of each row in a MATLAB spectrogram

I recently learned how to manually compute a spectrogram of an audio signal, which is essentially a matrix. Each column corresponds to a time frame (e.g. 10 ms or something) but I'm asking which row ...
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1answer
33 views

Add noise/signal to mel log spectrogram

I have a predicted mel log spectrogram $S$ and I want to add a noise signal $\eta$ to it. S = log(mel-filterbank(abs/real part of(stft(signal))) The naive way ...
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1answer
100 views

Apply windowing before FFT or after?

I am computing a spectrogram and I've found a code example online which goes like this: ...
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1answer
118 views

chirp signal - Frequency spectrum characteristics

I am confused with my own intuition of the frequency response of a chirp signal. In this case, the chirp signal is a frequency modulated signal with initial frequency starting at 100 Hz and ending at ...
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2answers
147 views

Quantify the difference between two audio spectrograms

I have two speech signals of the same length. They contain the exact same speech content but are recorded from two different microphones. I want to compare the differences between them. 1) Assuming ...
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1answer
40 views

is there a way to apply a median filter diagonally?

For example, some studies show how to smooth a spectrogram with a 2D median filter vertically and horizontally (along time or frequency). My question is how would I apply 2D median filter along the ...
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100 views

Reconstruct signal from its Spectrogram only

The spectrogram of a signal throws away the phase information, but it is said to be possible to reconstruct the signal only from the spectrogram [1] via $$s(t) = \frac{1}{2\pi s^*(0)}\int_{-\infty}^{\...
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106 views

Spectrogram parameters for Audio Fingerprinting

I'm using the specgram() function in matplotlib library to get Spectrogram of songs for Audio Fingerprinting (for musics) and making unique hashes for each song (something like shazam) and im sure im ...
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1answer
70 views

Distinguish harmonic sounds from non-harmonic

I am trying to distinguish harmonic sounds in the range from $100\rm \ Hz$ to $1000\rm \ Hz$ in my audio recording. I attach the spectrogram ($y$-axis is freqeuncy and $x$-axis is time) of a typical ...
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2answers
110 views

STFT computation

I'm trying to compute the STFT by my self. Thus, I wrote the following code: ...
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1answer
245 views

Is it possible to recover a waveform from spectrograms of magnitude *and* phase?

It is my rough understanding that a typical spectrogram discards phase information by squaring only the real-valued part (magnitude) of the STFT (I know it's not quite this simple, but feel free to ...
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1answer
55 views

How can you 'perfectly' reconstruct phase for transients in a modified audio absolute spectrogram?

I am currently working on the absolute spectrogram of an input audio signal. I am using non-negative matrix factorization to separate out the rhythmic components (bass drum, snare drum and hi-hat) of ...
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2answers
78 views

What's a good physical description of the following matlab code?

I've inherited some matlab code and I can't really understand what the resultant signal really means. The input is audio and the code first performs an STFT/spectrogram (sliding window FFT of size ...
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How can i find the time delay using spectrogram?

We observe that in the first plot we have a delayed signal and in the second one, his spectrogram. My question is how can i find the time delay using spectrogram. I understand that if i sum the colums ...
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320 views

Calculating spectrogram of a signal scipy.signal.spectrogram

I have a signal of length 1s, fs(sampling frequency) = 1000 Hz. I wish to do its time-frequency analysis. So i thought to use scipy.signal.spectrogram function with below parameters: ...
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1answer
1k views

scipy.signal.spectrogram

I want to do time-frequency analysis of a signal. So i decided to use spectrogram function from scipy. This function returns, three parameters f,t,Sxx. I am using below arguements: x : my signal fs : ...
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97 views

How to improve the word recognition rate on Kaldi?

I am working on speech recognition using Kaldi. We have model which is trained on male voice. We are trying to recognize female voice using this model, but getting less accuracy than male voice for ...
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39 views

What can i find in a spectrogram?

What information can i read from this spectrogram? I have 2 signals, the first one a sine and the second one a sine with noise
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31 views

What are some simple ways to corporate phase information into spectrogram factorization

In time-frequency representation, if I have prior information that each frequency should be presented in specific time range, are there any simple ways to corporate this information into spectrogram ...
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164 views

Hilbert Spectrum vs. STFT

If I wanted to plot a spectrogram of a signal, I would by default use the Short Time Fourier Transform. However, the Hilbert transform does something similar: it lets us calculate instantaneous ...
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319 views

Self studying, getting a quality spectrogram

So I've been self studying signal processing, and been trying to use Python to get quality spectrograms, quality spectrogram like the one that would be produced with audacity etc. The steps I have ...
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1answer
181 views

relationship of column of spectrogram to original signal

We can get the spectrograms of a signal which is a 2D matrix. How do I get back from the columns of the spectrogram to the time stamps in original signal? For example, what time stamp does the columns ...
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1answer
167 views

Is the Auditory Spectrogram the same as the Magnitude Spectrogram?

This is in the context of speech signals. The magnitude spectrogram is computed by framing the signal into short time windows, applying a hamming (or similar) window, computing the fft over each ...
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100 views

MATLAB - Getting frequency and time from spectrogram peaks

I am new to signal processing and need help understanding how to find the peaks of a Spectrogram in MATLAB. I have this spectrogram with clearly defined peaks, and want to find the time and frequency ...
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3answers
262 views

Spectogram of a signal

I am working on a seismic signal to extract long period long duration earthquakes. The sampling frequency is $2004\ \rm{ Hz}$ and the the signal has $20755200\ \rm{samples}$. The spectogram seems to ...
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1answer
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Speech signal formant spectrogram. How can we determine F1?

The formant spectrogram in this page points F1 and F2 as below; In bottom-right F1 movement, I thought F1 could be below blue one. But how can we determine F1 is upper one not below one? Is it ...
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161 views

Smooth looking spectrogram display

I'm working on a simple sound analyzer application and a main feature of this program is the spectrogram display. I want this spectrogram to render fast and to be good looking while preserving all the ...
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2answers
160 views

Combining spectrograms with different windows to getting arbitrary time and frequency resolution

Spectrograms convert an amplitude-time signal into a frequency-time signal using Short Time Fourier Transform (STFT). The window size L used in STFT is a design choice. As L increases, you get higher ...
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34 views

Should zero element be considered to calculate mean when smoothing spectrogram by window?

My (mass spectrometry) spectrogram does not measure the intensity constantly. I obtain the spectrogram, for example, ...
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19 views

How to find the quantity for channels by plotting spectrogram and periodogram with matlab

what I have done is that, get a signal, do fft on it, plot periodogram and spectrogram for this signal. However, from periodogram plot, there is too much noise and cannot find channel clearly. In ...